FabSwingers.com > Forums > The Lounge > Imagine a 747 is sitting on a conveyor belt, as wide and long as a runway.
Imagine a 747 is sitting on a conveyor belt, as wide and long as a runway.
Jump to: Newest in thread
 | |||
Reply privately (closed, thread got too big) | |||
| |||
Reply privately (closed, thread got too big) | |||
 | |||
Reply privately (closed, thread got too big) | |||
| |||
Reply privately (closed, thread got too big) | |||
| |||
Reply privately (closed, thread got too big) | |||
| |||
Reply privately (closed, thread got too big) | |||
"Yes it was proven on myth busters. End of thread " so why people still posting  | |||
Reply privately (closed, thread got too big) | |||
"Yes it was proven on myth busters. End of thread so why people still posting "If you look at the mythbusters video, the plane looks to be moving forward, its not at a constant speed. Also as a light aircraft a good head wind would lift it without any thrust | |||
Reply privately (closed, thread got too big) | |||
| |||
Reply privately (closed, thread got too big) | |||
| |||
Reply privately (closed, thread got too big) | |||
"There was a thread about this a month ago. Nearly caused a riot and had 3 parts to it over 2 days lol." oh, I never realised | |||
Reply privately (closed, thread got too big) | |||
"How can it? No forward motion= no airflow= no lift" Exactly this. The aerofoils rely on airflow to generate lift from opposing high & low pressures on opposite surfaces of the wing areas... If the wheels are rotating but conveyor matches, then rolling speed could be 200mph but airspeed is still zero so no airflow = no pressure differential so no lift. Science lesson over. I'm off for another G&T xx | |||
Reply privately (closed, thread got too big) | |||
Look up the xkcd aeroplane treadmill blog post, and don't fall for this flamebait ever again | |||
Reply privately (closed, thread got too big) | |||
| |||
Reply privately (closed, thread got too big) | |||
"The conveyor belt is designed to exactly match the speed of the wheels, moving in the opposite drection. Can the plane take off? Merry Christmas "Yes, as well you know OP, If the designer of this theoretical problem thought that the conveyor would work, why would they make it "as long as a runway" it would only need to be as long as wheel base.  | |||
Reply privately (closed, thread got too big) | |||
"The conveyor belt is designed to exactly match the speed of the wheels, moving in the opposite drection. Can the plane take off? Merry Christmas
Yes, as well you know OP, If the designer of this theoretical problem thought that the conveyor would work, why would they make it "as long as a runway" it would only need to be as long as wheel base. "Good point. The airplane wheels are not driven by the plane.. They facilitate its contact with the earth.. Thats all.. And should reduce a lot of the friction. Therefore the thrust of the, engines, would, still move the plane, forward and would reach take of speed and then lift off would be possible.?? | |||
Reply privately (closed, thread got too big) | |||
"There was a thread about this a month ago. Nearly caused a riot and had 3 parts to it over 2 days lol. oh, I never realised "No worries pal. Wasnt having a dig at you. Lets just say the last one got very heated lol. | |||
Reply privately (closed, thread got too big) | |||
"The conveyor belt is designed to exactly match the speed of the wheels, moving in the opposite drection. Can the plane take off? Merry Christmas
Yes, as well you know OP, If the designer of this theoretical problem thought that the conveyor would work, why would they make it "as long as a runway" it would only need to be as long as wheel base. "If it was possible to launch a plane off a conveyor belt, wouldnt they make smaller aircraft carriers? | |||
Reply privately (closed, thread got too big) | |||
"If it was possible to launch a plane off a conveyor belt, wouldnt they make smaller aircraft carriers?" Well they do use some tricks to make aircraft carriers work with shorter runways, blast wall so the thrusters have something to push against, and a big elastic band to speed up launch, and catchers for landing (which can be a bigger problem) | |||
Reply privately (closed, thread got too big) | |||
| |||
Reply privately (closed, thread got too big) | |||
"The conveyor belt is designed to exactly match the speed of the wheels, moving in the opposite drection. Can the plane take off? Merry Christmas "This was done to death and the only people who don't understand it are those who do not understand Bernoulli's principles and the basic principles of flight. An aircraft needs airflow over the wing to fly. That airflow is provided by movement through the air and is separate to the thrust delivered by the jet, propellor or other motor - albeit the motor is there to provide the necessary forward motion. Speed over the ground is completely irrelevant, all that matters is the speed of the wing through the airflow. An aircraft flies at a given airspeed, not ground speed and that is why aircraft will invariably take off and land into wind as this affects wear and tear on wheels and brakes and there may not even be enough runway to take off if there is a significant tail wind component. Example - aircraft rotates at 150mph air and ground speed in say 1,000 metres in still air With a 40 mph head wind, aircraft rotates at 110mph ground speed & 150mph air speed in say 700 metres With a 40 mph tail wind, aircraft rotates at 190mph ground speed and 150mph air speed in say 1,500 metres Anyone who doubts this, try this little experiment. On a windy day, stand facing the wind and hold your arm out flat with your hand parallel to the ground. Slowly twist your hand through 45 degrees and you will feel the wind hitting the palm of your hand and pushing it backwards and upwards. Now run towards the wind and do the same and you will a more obvious sensation of lift and pushing on your hand. Finally turn around and run with the wind doing the same thing and you will feel no sensation at all of pushing or lift until (and if) your running speed can be faster than the wind speed. In all cases what is happening to your hand is a very crude version of what happens to a wing. Clearly when it comes to landing it is much more preferable to be approaching at an airspeed that is relatively slower across the ground than faster, and so landing into a headwind reduces the speed over the ground. PS it is perfectly possible to fly a light aircraft backwards over the ground whilst maintaining flying speed in the air. | |||
Reply privately (closed, thread got too big) | |||
| |||
Reply privately (closed, thread got too big) | |||
" The airplane wheels are not driven by the plane.. They facilitate its contact with the earth.. Thats all.. And should reduce a lot of the friction. Therefore the thrust of the, engines, would, still move the plane, forward and would reach take of speed and then lift off would be possible.?? " Exactly this. The wheels, ground and any contact with it have NO bearing on the forward speed (air speed) of the THRUST propelled aircraft. Even if the conveyor was going backwards at 1,000,000 mph the plane would STILL be pushed fieards by the thrust. The plane takes off as normal. End of argument. | |||
Reply privately (closed, thread got too big) | |||
| |||
Reply privately (closed, thread got too big) | |||
"If it was possible to launch a plane off a conveyor belt, wouldnt they make smaller aircraft carriers? Well they do use some tricks to make aircraft carriers work with shorter runways, blast wall so the thrusters have something to push against, and a big elastic band to speed up launch, and catchers for landing (which can be a bigger problem) " not forgetting facing in to the wind | |||
Reply privately (closed, thread got too big) | |||
"If it was possible to launch a plane off a conveyor belt, wouldnt they make smaller aircraft carriers? Well they do use some tricks to make aircraft carriers work with shorter runways, blast wall so the thrusters have something to push against, and a big elastic band to speed up launch, and catchers for landing (which can be a bigger problem) not forgetting facing in to the wind" Can we add a Christmas theme by evaluating if a 747 takes off quicker if everyone eats sprouts? | |||
Reply privately (closed, thread got too big) | |||
| |||
Reply privately (closed, thread got too big) | |||
"No" You are just mean 
 | |||
Reply privately (closed, thread got too big) | |||
"Who fookin cares "This. | |||
Reply privately (closed, thread got too big) | |||
"If it was possible to launch a plane off a conveyor belt, wouldnt they make smaller aircraft carriers? Well they do use some tricks to make aircraft carriers work with shorter runways, blast wall so the thrusters have something to push against, and a big elastic band to speed up launch, and catchers for landing (which can be a bigger problem) " No, please no! The 'thrusters' don't push on the jet blast deflectors, or on the air! | |||
Reply privately (closed, thread got too big) | |||
"If it was possible to launch a plane off a conveyor belt, wouldnt they make smaller aircraft carriers? Well they do use some tricks to make aircraft carriers work with shorter runways, blast wall so the thrusters have something to push against, and a big elastic band to speed up launch, and catchers for landing (which can be a bigger problem) No, please no! The 'thrusters' don't push on the jet blast deflectors, or on the air!" Noooooooooo ! The Physics part 1, 2 and 3 threads at 175 drove us mad enough lol | |||
Reply privately (closed, thread got too big) | |||
"The conveyor belt is designed to exactly match the speed of the wheels, moving in the opposite drection. Can the plane take off? Merry Christmas
Yes, as well you know OP, If the designer of this theoretical problem thought that the conveyor would work, why would they make it "as long as a runway" it would only need to be as long as wheel base.
If it was possible to launch a plane off a conveyor belt, wouldnt they make smaller aircraft carriers?"And it would solve the Heathrow 3rd runway problem. | |||
Reply privately (closed, thread got too big) | |||
| |||
Reply privately (closed, thread got too big) | |||
"The conveyor belt is designed to exactly match the speed of the wheels, moving in the opposite drection. Can the plane take off? Merry Christmas
Yes, as well you know OP, If the designer of this theoretical problem thought that the conveyor would work, why would they make it "as long as a runway" it would only need to be as long as wheel base.
If it was possible to launch a plane off a conveyor belt, wouldnt they make smaller aircraft carriers?
And it would solve the Heathrow 3rd runway problem. "Very good point!  | |||
Reply privately (closed, thread got too big) | |||
"The conveyor belt is designed to exactly match the speed of the wheels, moving in the opposite drection. Can the plane take off? Merry Christmas
Yes, as well you know OP, If the designer of this theoretical problem thought that the conveyor would work, why would they make it "as long as a runway" it would only need to be as long as wheel base.
If it was possible to launch a plane off a conveyor belt, wouldnt they make smaller aircraft carriers?
And it would solve the Heathrow 3rd runway problem.
Very good point! "Nobody is saying a stationary aircraft will fly. We are saying the plane will move forwards as normal. | |||
Reply privately (closed, thread got too big) | |||
"If it was possible to launch a plane off a conveyor belt, wouldnt they make smaller aircraft carriers? Well they do use some tricks to make aircraft carriers work with shorter runways, blast wall so the thrusters have something to push against, and a big elastic band to speed up launch, and catchers for landing (which can be a bigger problem) No, please no! The 'thrusters' don't push on the jet blast deflectors, or on the air! Noooooooooo ! The Physics part 1, 2 and 3 threads at 175 drove us mad enough lol" I don't see why this is so hard! Yet people are still convinced the plane wouldn't move, oh dear! | |||
Reply privately (closed, thread got too big) | |||
"The conveyor belt is designed to exactly match the speed of the wheels, moving in the opposite drection. Can the plane take off? Merry Christmas
Yes, as well you know OP, If the designer of this theoretical problem thought that the conveyor would work, why would they make it "as long as a runway" it would only need to be as long as wheel base.
If it was possible to launch a plane off a conveyor belt, wouldnt they make smaller aircraft carriers?
And it would solve the Heathrow 3rd runway problem.
Very good point! "The runway/conveyor belt would still need to be the same length, a conveyor just wouldn't prevent the plane from gaining forward momentum. Cal | |||
Reply privately (closed, thread got too big) | |||
| |||
Reply privately (closed, thread got too big) | |||
"The conveyor belt is designed to exactly match the speed of the wheels, moving in the opposite drection. Can the plane take off? Merry Christmas
Yes, as well you know OP, If the designer of this theoretical problem thought that the conveyor would work, why would they make it "as long as a runway" it would only need to be as long as wheel base.
If it was possible to launch a plane off a conveyor belt, wouldnt they make smaller aircraft carriers?
And it would solve the Heathrow 3rd runway problem.
Very good point!
The runway/conveyor belt would still need to be the same length, a conveyor just wouldn't prevent the plane from gaining forward momentum.
Cal"Look on the useful side, said runway length conveyor would mean all the FOD would be automatically removed rather than being a danger to aircraft! | |||
Reply privately (closed, thread got too big) | |||
"Why do you lot get so angry. If you don't like what someone is posting why dont you trot on to the next post. Chill. There's a word. Tr........" Fecking a men! | |||
Reply privately (closed, thread got too big) | |||
" Fecking a men! "Surely that's eithe some men... or a man? | |||
Reply privately (closed, thread got too big) | |||
" Fecking a men!
Surely that's eithe some men... or a man?
"As in 'Amen' | |||
Reply privately (closed, thread got too big) | |||
didn't get involved last time so sorry to keep this going.... but after getting d*unk, sleeping on it and waking up....i'm now convined that yes, it would go forwards as normal....i sit corrected ( suspect the wheels would be spinning at a silly rate of knots at the end of the run though! ) | |||
Reply privately (closed, thread got too big) | |||
" didn't get involved last time so sorry to keep this going.... but after getting d*unk, sleeping on it and waking up....i'm now convined that yes, it would go forwards as normal....i sit corrected ( suspect the wheels would be spinning at a silly rate of knots at the end of the run though! )"That's no good, your sober thoughts are not going to keep this mythical conundrum alive, get d*unk again then answer | |||
Reply privately (closed, thread got too big) | |||
| |||
Reply privately (closed, thread got too big) | |||
"As the Physics 3 post ended...." I detect a level of evil in you sir, your username indicates Gentleman, though now I have a vision of you twirling your moustache in a dastardly way | |||
Reply privately (closed, thread got too big) | |||
"As the Physics 3 post ended.... I detect a level of evil in you sir, your username indicates Gentleman, though now I have a vision of you twirling your moustache in a dastardly way "No terry Thomas moustache. I am stroking my big white cat whilst looking at a massive map of the world that I have on my floor. I'm currently aiming warplanes at Benidorm. Problem is the conveyor belt under the planes is running and the damn things wont take off!!! | |||
Reply privately (closed, thread got too big) | |||
"No terry Thomas moustache. I am stroking my big white cat whilst looking at a massive map of the world that I have on my floor. I'm currently aiming warplanes at Benidorm. Problem is the conveyor belt under the planes is running and the damn things wont take off!!!" That is a worthy evil genius persona. and a good target for your war planes... secret tip, start the engines and they will take off | |||
Reply privately (closed, thread got too big) | |||
"The conveyor belt is designed to exactly match the speed of the wheels, moving in the opposite drection. Can the plane take off? Merry Christmas "Yes. And I love this new thread. We need to discuss this serious issue more! | |||
Reply privately (closed, thread got too big) | |||
| |||
Reply privately (closed, thread got too big) | |||
| |||
Reply privately (closed, thread got too big) | |||
| |||
Reply privately (closed, thread got too big) | |||
| |||
Reply privately (closed, thread got too big) | |||
"Might the Banach-Tarski paradox have a role to play here? " I don't know, I don't listen to prog rock | |||
Reply privately (closed, thread got too big) | |||
| |||
Reply privately (closed, thread got too big) | |||
"As the Physics 3 post ended.... I detect a level of evil in you sir, your username indicates Gentleman, though now I have a vision of you twirling your moustache in a dastardly way
No terry Thomas moustache. I am stroking my big white cat whilst looking at a massive map of the world that I have on my floor. I'm currently aiming warplanes at Benidorm. Problem is the conveyor belt under the planes is running and the damn things wont take off!!!"Schroedinger wants his cat back so he can get on with piloting the hypothetical plane! | |||
Reply privately (closed, thread got too big) | |||
 | |||
Reply privately (closed, thread got too big) | |||
"Mythbusters did do this on smaller scale with a cessna and it did work, even when logically thought about, it shouldn't. I would argue that having no forward motion, and therefore no lift on generated by the wings, the plane should not take off. But it was proven it could, I forget the science behind it. "What makes you think there's no forward motion? | |||
Reply privately (closed, thread got too big) | |||
"Bit bored of the conveyor belt now... how about if the plane was on a roundabout, with the brakes on so the engines span the roundabout... could it reach take off speed, and would it centrafuge the passengers? "If a plane could do takeoff speeds on a standard roundabout then it's likely the passengers (and pilots, crew, on-board food) would separate at least partly into their component parts. Of course, that is due to centripetal force | |||
Reply privately (closed, thread got too big) | |||
"Mythbusters did do this on smaller scale with a cessna and it did work, even when logically thought about, it shouldn't. I would argue that having no forward motion, and therefore no lift on generated by the wings, the plane should not take off. But it was proven it could, I forget the science behind it.
What makes you think there's no forward motion?"Reiterated Why think there was no forward force or motion xx | |||
Reply privately (closed, thread got too big) | |||
"Bit bored of the conveyor belt now... how about if the plane was on a roundabout, with the brakes on so the engines span the roundabout... could it reach take off speed, and would it centrafuge the passengers?
If a plane could do takeoff speeds on a standard roundabout then it's likely the passengers (and pilots, crew, on-board food) would separate at least partly into their component parts. Of course, that is due to centripetal force "Obviously you can't just use the roundabout from the park, it would need to be quite a lot bigger... but apart from the minor inconvenience of seppearting passengers into component parts, it could be a good idea. If you put 2 planes on it at the same time facing opposite ways they could get airborne on half the fuel. Problem would be the landing I think... I remember jumping off the roundabout at high speed being fun, but jumping on them tended to cause split lips, black eyes etc. | |||
Reply privately (closed, thread got too big) | |||
"Problem would be the landing I think... I remember jumping off the roundabout at high speed being fun, but jumping on them tended to cause split lips, black eyes etc. "Ah, by "roundabout" you mean "merry-go-round", not "road arranged into a circle with junctions". | |||
Reply privately (closed, thread got too big) | |||
"Last time this was forum' d it almost made me give up on the forums all together haha Stationary airplane cannot take off. End off. " *cough* Harrier or the US Marine Corp Osprey? | |||
Reply privately (closed, thread got too big) | |||
"Problem would be the landing I think... I remember jumping off the roundabout at high speed being fun, but jumping on them tended to cause split lips, black eyes etc.
Ah, by "roundabout" you mean "merry-go-round", not "road arranged into a circle with junctions"."Of course localised language would need to be dealt with before this becomes a serious scientific endeavour. | |||
Reply privately (closed, thread got too big) | |||
"Mythbusters did do this on smaller scale with a cessna and it did work, even when logically thought about, it shouldn't. I would argue that having no forward motion, and therefore no lift on generated by the wings, the plane should not take off. But it was proven it could, I forget the science behind it.
What makes you think there's no forward motion?
Reiterated
Why think there was no forward force or motion xx
"Because the conveyor belt is running against the plane at the same speed it is moving at, effectivly cancelling out the thrust. The plane is pretty much standing still. | |||
Reply privately (closed, thread got too big) | |||
" Because the conveyor belt is running against the plane at the same speed it is moving at, effectivly cancelling out the thrust. The plane is pretty much standing still. " Next time you're at the gym take a little toy car. Hold it on a moving treadmill with your finger tips. Then push it forwards. Does it move forwards, or does it remain held magically stationary by the treadmill belt? | |||
Reply privately (closed, thread got too big) | |||
" Because the conveyor belt is running against the plane at the same speed it is moving at, effectivly cancelling out the thrust. The plane is pretty much standing still. Next time you're at the gym take a little toy car. Hold it on a moving treadmill with your finger tips. Then push it forwards. Does it move forwards, or does it remain held magically stationary by the treadmill belt?" The toy car does not have its own continuous thrust from a single push. A jet plane would from its own engines. | |||
Reply privately (closed, thread got too big) | |||
" Because the conveyor belt is running against the plane at the same speed it is moving at, effectivly cancelling out the thrust. The plane is pretty much standing still. Next time you're at the gym take a little toy car. Hold it on a moving treadmill with your finger tips. Then push it forwards. Does it move forwards, or does it remain held magically stationary by the treadmill belt? The toy car does not have its own continuous thrust from a single push. A jet plane would from its own engines." The toy car moves forward by your hand. The plane moves forward from the jets. | |||
Reply privately (closed, thread got too big) | |||
"Mythbusters did do this on smaller scale with a cessna and it did work, even when logically thought about, it shouldn't. I would argue that having no forward motion, and therefore no lift on generated by the wings, the plane should not take off. But it was proven it could, I forget the science behind it.
What makes you think there's no forward motion?
Reiterated
Why think there was no forward force or motion xx
Because the conveyor belt is running against the plane at the same speed it is moving at, effectivly cancelling out the thrust.
The plane is pretty much standing still. "
The trust is from the engine not the wheels. The thrust from the engine would push the plane forward but the wheels would be travelling at twice the speed that the plane is travelling. So if the plane has a take off speed of 100mph at take off the wheels will be doing 200mph...
| |||
Reply privately (closed, thread got too big) | |||
| |||
Reply privately (closed, thread got too big) | |||
"The conveyor belt is designed to exactly match the speed of the wheels, moving in the opposite drection. Can the plane take off? Merry Christmas "Yes because the mass of the aircraft accelerates forward in reaction to the thrust from the engine. The plane moves relative to the air, not relative to the ground. There is no drive through the wheels. Busted on XKCD | |||
Reply privately (closed, thread got too big) | |||
"they do use some tricks to make aircraft carriers work with shorter runways, blast wall so the thrusters have something to push against " To push against?? Seriously? What propels the engine? Its forward reaction to the rearward thrust... O level Newtonian mechanics. What is the blast wall for? To protect the rest of the carrier flat top, the crews and other planes. | |||
Reply privately (closed, thread got too big) | |||
| |||
Reply privately (closed, thread got too big) | |||
| |||
Reply privately (closed, thread got too big) | |||
"Imagine a train going along a straight track at say 20 mph (it doesn't matter but a slow speed). A fly flies along the track in the opposite direction, lands on the front of the train and is then carried on the front of the train (alive not squished!) in the opposite direction. As the fly must have changed direction from forwards to backwadrds it must have stopped for an instant to do so; therefore as the fly was always in contact with the train; the train must have stopped as well? Over to you." Er? What? | |||
Reply privately (closed, thread got too big) | |||
"they do use some tricks to make aircraft carriers work with shorter runways, blast wall so the thrusters have something to push against To push against?? Seriously? What propels the engine? Its forward reaction to the rearward thrust... O level Newtonian mechanics. What is the blast wall for? To protect the rest of the carrier flat top, the crews and other planes. " This is such a common misconception, isn't it! People think that jets and rockets push on something. How do they work in space then? Then there are those that will tell us there is no gravity on the ISS! | |||
Reply privately (closed, thread got too big) | |||
"Imagine a train going along a straight track at say 20 mph (it doesn't matter but a slow speed). A fly flies along the track in the opposite direction, lands on the front of the train and is then carried on the front of the train (alive not squished!) in the opposite direction. As the fly must have changed direction from forwards to backwadrds it must have stopped for an instant to do so; therefore as the fly was always in contact with the train; the train must have stopped as well? Over to you." The legs of the fly would absorbe the impact by compressing.. | |||
Reply privately (closed, thread got too big) | |||
| |||
Reply privately (closed, thread got too big) | |||
"No" Which scenario are you saying no to ? A plane not moving with no engines on a treadmill won't take off ? Or a plane with 90 000 lbs of thrust accelerating at 10 m/s 2 reaching an air speed over 150 mph won't take off ? | |||
Reply privately (closed, thread got too big) | |||
"Imagine a train going along a straight track at say 20 mph (it doesn't matter but a slow speed). A fly flies along the track in the opposite direction, lands on the front of the train and is then carried on the front of the train (alive not squished!) in the opposite direction. As the fly must have changed direction from forwards to backwadrds it must have stopped for an instant to do so; therefore as the fly was always in contact with the train; the train must have stopped as well? Over to you. The legs of the fly would absorbe the impact by compressing.." And the air in front of the train would act as a cushion and by the time the fly comes into contact with the train it is moving in the same direction as the train but at a slightly slower speed than the train... | |||
Reply privately (closed, thread got too big) | |||
"Imagine a train going along a straight track at say 20 mph (it doesn't matter but a slow speed). A fly flies along the track in the opposite direction, lands on the front of the train and is then carried on the front of the train (alive not squished!) in the opposite direction. As the fly must have changed direction from forwards to backwadrds it must have stopped for an instant to do so; therefore as the fly was always in contact with the train; the train must have stopped as well? Over to you. The legs of the fly would absorbe the impact by compressing.." What if the fly was Heather Mills McCartney | |||
Reply privately (closed, thread got too big) | |||
"Imagine a train going along a straight track at say 20 mph (it doesn't matter but a slow speed). A fly flies along the track in the opposite direction, lands on the front of the train and is then carried on the front of the train (alive not squished!) in the opposite direction. As the fly must have changed direction from forwards to backwadrds it must have stopped for an instant to do so; therefore as the fly was always in contact with the train; the train must have stopped as well? Over to you. The legs of the fly would absorbe the impact by compressing.. What if the fly was Heather Mills McCartney "In that case she would just be a little splat on the front of the train... | |||
Reply privately (closed, thread got too big) | |||
"Imagine a train going along a straight track at say 20 mph (it doesn't matter but a slow speed). A fly flies along the track in the opposite direction, lands on the front of the train and is then carried on the front of the train (alive not squished!) in the opposite direction. As the fly must have changed direction from forwards to backwadrds it must have stopped for an instant to do so; therefore as the fly was always in contact with the train; the train must have stopped as well? Over to you." What if the train was travelling at the speed of light. Would the light coming from its headlamp come out, or just bunch up in the bulb? | |||
Reply privately (closed, thread got too big) | |||
"they do use some tricks to make aircraft carriers work with shorter runways, blast wall so the thrusters have something to push against To push against?? Seriously? What propels the engine? Its forward reaction to the rearward thrust... O level Newtonian mechanics. What is the blast wall for? To protect the rest of the carrier flat top, the crews and other planes. This is such a common misconception, isn't it! People think that jets and rockets push on something. How do they work in space then? Then there are those that will tell us there is no gravity on the ISS! " Pretty sure jets don't work in space, jet it propeller propulsion basically takes some air or water from in front of you and puts it behind you, this may possibly make a small vacuum that may pull you forward, but most of the measurable thrust comes from compression of the air or water behind you. If you are ever on a jet ski, try hitting the throttle with the back of the ski close to an immovable object e.g. a harbour wall, it gives significantly more forward thrust than doing the same in open water. So I still hold that sticking a blast wall behind a jet engine does more than prevent sailors hats get blown off... | |||
Reply privately (closed, thread got too big) | |||
"What if the train was travelling at the speed of light. Would the light coming from its headlamp come out, or just bunch up in the bulb?" If a train is coming at you at the speed of light, can you see it? if not was it there? | |||
Reply privately (closed, thread got too big) | |||
"What if the train was travelling at the speed of light. Would the light coming from its headlamp come out, or just bunch up in the bulb? If a train is coming at you at the speed of light, can you see it? if not was it there? " quality | |||
Reply privately (closed, thread got too big) | |||
| |||
Reply privately (closed, thread got too big) | |||
| |||
Reply privately (closed, thread got too big) | |||
"Yes" It has jet engines End of thread | |||
Reply privately (closed, thread got too big) | |||
"What if the train was travelling at the speed of light. Would the light coming from its headlamp come out, or just bunch up in the bulb? If a train is coming at you at the speed of light, can you see it? if not was it there? "Yes, you'd see it coming. Don't ask me to explain why, I just barely understand it myself lol | |||
Reply privately (closed, thread got too big) | |||
| |||
Reply privately (closed, thread got too big) | |||
"What if the train was travelling at the speed of light. Would the light coming from its headlamp come out, or just bunch up in the bulb? If a train is coming at you at the speed of light, can you see it? if not was it there? "Personally, I would say no, you wouldn't see it as it's travelling too fast for your brain to process. To explain my random thoughts - your theoretical train would be over 2,400 miles away before it splats you 13 milliseconds later which is the time that it would have taken your brain to process the image (I think) | |||
Reply privately (closed, thread got too big) | |||
"What if the train was travelling at the speed of light. Would the light coming from its headlamp come out, or just bunch up in the bulb? If a train is coming at you at the speed of light, can you see it? if not was it there?
Personally, I would say no, you wouldn't see it as it's travelling too fast for your brain to process.
To explain my random thoughts - your theoretical train would be over 2,400 miles away before it splats you 13 milliseconds later which is the time that it would have taken your brain to process the image (I think) "Ok, but if it was a space train, 1 light year away, travelling towards you with its headlights on. What would you see and what would the train passenger see? | |||
Reply privately (closed, thread got too big) | |||
" Personally, I would say no, you wouldn't see it as it's travelling too fast for your brain to process. To explain my random thoughts - your theoretical train would be over 2,400 miles away before it splats you 13 milliseconds later which is the time that it would have taken your brain to process the image (I think)
Ok, but if it was a space train, 1 light year away, travelling towards you with its headlights on.
What would you see and what would the train passenger see?"Lol ... too geeky, even for me 
Would not the same still apply given the time needed to process the image by the brain? One cannot see a train or a small light 2400 miles away and the passenger's on that train could not see you either at that distance so you would still be splatted without any idea of these damned trains flying around so recklessly.
I did try and read Hawking's book a while back and have to admit to being a little confused | |||
Reply privately (closed, thread got too big) | |||
| |||
Reply privately (closed, thread got too big) | |||
" Ok, but if it was a space train, 1 light year away, travelling towards you with its headlights on. What would you see and what would the train passenger see? Lol ... too geeky, even for me
Would not the same still apply given the time needed to process the image by the brain? One cannot see a train or a small light 2400 miles away and the passenger's on that train could not see you either at that distance so you would still be splatted without any idea of these damned trains flying around so recklessly.
I did try and read Hawking's book a while back and have to admit to being a little confused "Ha yes, I just understand the concept while reading the books. Then afterwards am confused again lol. But bits are seeping in to my brain. Overcoming our 'common sense' of space and time is very hard..... | |||
Reply privately (closed, thread got too big) | |||
| |||
Reply privately (closed, thread got too big) | |||
"Not all light travels at the speed of light..." Only Bud Light travels slower
All the rest goes at the same speed in a vacuum. | |||
Reply privately (closed, thread got too big) | |||
"Not all light travels at the speed of light... Only Bud Light travels slower
All the rest goes at the same speed in a vacuum."Though I suspect it may go faster in a Dyson | |||
Reply privately (closed, thread got too big) | |||
"Not all light travels at the speed of light... Only Bud Light travels slower
All the rest goes at the same speed in a vacuum.
Though I suspect it may go faster in a Dyson "No bag to slow it down | |||
Reply privately (closed, thread got too big) | |||
"Pretty sure jets don't work in space, jet it propeller propulsion basically takes some air or water from in front of you and puts it behind you, this may possibly make a small vacuum that may pull you forward, but most of the measurable thrust comes from compression of the air or water behind you." No... the forward force is reaction to the rearward thrust... that's it... no compression or 'pushing' involved. There could be trivial second order effects of thrust blasting against a nearby wall however this is minimal compared with the newtonian reaction force. Secondly there is no 'vacuum' pulling the engine forward. The reason jets don't work in space is because there is no air to enter the engine so rockets carry their own oxygen to create the reaction which creates the rearward thrust. However the newtonian mechanics of it are identical, forward force in reaction to the rearward thrust causes the object to accelerate forwards. O-level physics. As verified by my Cambridge MPhys child who participated in the mass debunking of this hypothetical example on XKCD. The key issue is what happens at the point at which the wheels touch the conveyor belt due to the rotation of the wheels relative to the conveyor belt. And the critical issue is the coefficient of friction at that point. 1. If there was little friction then the plane would just take off. 2. If there was a little more friction then the may cause the tyres to slip with such frictional energy that the tyres may catch fire due to the frictional heat created by the mismatch rotational speeds - BUT the plane will take off 3. If the friction is so great that the tyres stay locked to the conveyor belt then it becomes an impossible scenario as the wheel will be rotating at twice the speed of the conveyor belt so it couldn't happen. The most likely scenario in that case would be that the plane would not take off but would instead tip over and spear itself into the runway. | |||
Reply privately (closed, thread got too big) | |||
" If you are ever on a jet ski, try hitting the throttle with the back of the ski close to an immovable object" Curious now... how do you think the force exerted on the immovable object (eg blast wall) gets transmitted to the jet ski (or plane) ? | |||
Reply privately (closed, thread got too big) | |||
"Pretty sure jets don't work in space" Of course, they don't, they need oxygen, my mistake there! " jet it propeller propulsion basically takes some air or water from in front of you and puts it behind you, this may possibly make a small vacuum that may pull you forward, but most of the measurable thrust comes from compression of the air or water behind you." No. As others have explained, it's all about Newton's Third Law. How do rockets work in space if it's anything else? "If you are ever on a jet ski, try hitting the throttle with the back of the ski close to an immovable object e.g. a harbour wall, it gives significantly more forward thrust than doing the same in open water. So I still hold that sticking a blast wall behind a jet engine does more than prevent sailors hats get blown off... "No, the JBD is there to stop anything loose being blown off the deck. End of. | |||
Reply privately (closed, thread got too big) | |||
" If you are ever on a jet ski, try hitting the throttle with the back of the ski close to an immovable object Curious now... how do you think the force exerted on the immovable object (eg blast wall) gets transmitted to the jet ski (or plane) ?" I undertand how the jet and jet ski move, and a wall shouldn't have any influence on either. In the case of the jet ski, if the poster has experienced this effect, I wonder if there is an additional factor coming into play? Water is viscous and maybe as the jet ski pumps the hundreds of gallons of water out behind it, if there is a wall it will well up and flow back exerting forward force on the back of the jet ski. Can't see it happening with a jet and a blast wall though, with air. | |||
Reply privately (closed, thread got too big) | |||
" If you are ever on a jet ski, try hitting the throttle with the back of the ski close to an immovable object Curious now... how do you think the force exerted on the immovable object (eg blast wall) gets transmitted to the jet ski (or plane) ? I undertand how the jet and jet ski move, and a wall shouldn't have any influence on either. In the case of the jet ski, if the poster has experienced this effect, I wonder if there is an additional factor coming into play? Water is viscous and maybe as the jet ski pumps the hundreds of gallons of water out behind it, if there is a wall it will well up and flow back exerting forward force on the back of the jet ski. Can't see it happening with a jet and a blast wall though, with air." That would make sense, that the impulse of the water molecules hitting the boat (NB, not the wall!) causes a force on the boat. One thing is certain, the jet isn't pushing on the wall. | |||
Reply privately (closed, thread got too big) | |||
" Water is viscous and maybe as the jet ski pumps the hundreds of gallons of water out behind it, if there is a wall it will well up and flow back exerting forward force on the back of the jet ski. Can't see it happening with a jet and a blast wall though, with air." I can't see any mechanism for the force of the jet of water FROM the jet ski on the wall causing a force on the jet ski that the water jet came from. I'd like to understand how that could happen. Water is incompressible (to all intents and purposes) and so maybe you're right that the VOLUME of water being pumped into the space between the jet ski and the wall causes a rebound wave that pushes the jet ski. However this is not an effect caused by the jet of water. | |||
Reply privately (closed, thread got too big) | |||
" Water is viscous and maybe as the jet ski pumps the hundreds of gallons of water out behind it, if there is a wall it will well up and flow back exerting forward force on the back of the jet ski. Can't see it happening with a jet and a blast wall though, with air. I can't see any mechanism for the force of the jet of water FROM the jet ski on the wall causing a force on the jet ski that the water jet came from. I'd like to understand how that could happen. Water is incompressible (to all intents and purposes) and so maybe you're right that the VOLUME of water being pumped into the space between the jet ski and the wall causes a rebound wave that pushes the jet ski. However this is not an effect caused by the jet of water. " I was thinking the water hits the wall, no effect on ski/boat. The water bounces of wall (simple conservation of momemtum), no effect on ski/boat. The rebounding water hits ski/boat and gives a impulse on the ski/boat. This, not the water hitting the wall, gives a force on the ski/boat. But I do like your point, basically as the water pushes into the gap the ski/boat is carried put on a wave as the water escapes. | |||
Reply privately (closed, thread got too big) | |||
" Water is viscous and maybe as the jet ski pumps the hundreds of gallons of water out behind it, if there is a wall it will well up and flow back exerting forward force on the back of the jet ski. Can't see it happening with a jet and a blast wall though, with air. I can't see any mechanism for the force of the jet of water FROM the jet ski on the wall causing a force on the jet ski that the water jet came from. I'd like to understand how that could happen. Water is incompressible (to all intents and purposes) and so maybe you're right that the VOLUME of water being pumped into the space between the jet ski and the wall causes a rebound wave that pushes the jet ski. However this is not an effect caused by the jet of water. " The jetskier is describing what he experiences in real life. So the thing is to explain why it could happen. It's not a 'jet' effect but is a secondary effect of it acting as a pump in a confined space. | |||
Reply privately (closed, thread got too big) | |||
"Imagine a train going along a straight track at say 20 mph (it doesn't matter but a slow speed). A fly flies along the track in the opposite direction, lands on the front of the train and is then carried on the front of the train (alive not squished!) in the opposite direction. As the fly must have changed direction from forwards to backwadrds it must have stopped for an instant to do so; therefore as the fly was always in contact with the train; the train must have stopped as well? Over to you. The legs of the fly would absorbe the impact by compressing.. What if the fly was Heather Mills McCartney
In that case she would just be a little splat on the front of the train... "what would be the last thing to go through her mind .... Answer .. her arsehole | |||
Reply privately (closed, thread got too big) | |||
"Not all light travels at the speed of light..." Flora light takes all day to go through me .. Bud light would take about an hour | |||
Reply privately (closed, thread got too big) | |||
"Not all light travels at the speed of light..." Er? Please explain this. All EM waves travel at the speed of light for the medium that they are in. | |||
Reply privately (closed, thread got too big) | |||
"What if the train was travelling at the speed of light. Would the light coming from its headlamp come out, or just bunch up in the bulb? If a train is coming at you at the speed of light, can you see it? if not was it there? "you're going to be splatted next to Heather Mills and a fly | |||
Reply privately (closed, thread got too big) | |||
"What if the train was travelling at the speed of light. Would the light coming from its headlamp come out, or just bunch up in the bulb? If a train is coming at you at the speed of light, can you see it? if not was it there?
Yes, you'd see it coming. Don't ask me to explain why, I just barely understand it myself lol"Actually no you don't xxx sorry | |||
Reply privately (closed, thread got too big) | |||
"What if the train was travelling at the speed of light. Would the light coming from its headlamp come out, or just bunch up in the bulb? If a train is coming at you at the speed of light, can you see it? if not was it there?
Yes, you'd see it coming. Don't ask me to explain why, I just barely understand it myself lol
Actually no you don't xxx sorry "Well, I understand it enough to know you'd see it coming. But you can explain more if you believe I've got it wrong. | |||
Reply privately (closed, thread got too big) | |||
| |||
Reply privately (closed, thread got too big) | |||
"What if the train was travelling at the speed of light. Would the light coming from its headlamp come out, or just bunch up in the bulb? If a train is coming at you at the speed of light, can you see it? if not was it there?
Yes, you'd see it coming. Don't ask me to explain why, I just barely understand it myself lol
Actually no you don't xxx sorry
Well, I understand it enough to know you'd see it coming.
But you can explain more if you believe I've got it wrong."Simple The speed of light cannot be exceeded even by light xx Thus train traveling at light speed arrives at exactly the same time as the light emitted this assumes that the lights were not switched on before the train departs if so the light will be seen exactly that time before the train arrives However if the gravity of the train were to affect space time we have a differing scenario but that really does become complex xxx | |||
Reply privately (closed, thread got too big) | |||
" Simple The speed of light cannot be exceeded even by light xx Thus train traveling at light speed arrives at exactly the same time as the light emitted this assumes that the lights were not switched on before the train departs if so the light will be seen exactly that time before the train arrives However if the gravity of the train were to affect space time we have a differing scenario but that really does become complex xxx" That's right the speed of light cannot be exceeded and remains unchanged for all observers. So when sat on the space train travelling at 99.99% lightspeed, light shines from its headlamp as normal and travels away from the train at the speed of light, as observed from the train. Forget the gravity stuff, it is another story. | |||
Reply privately (closed, thread got too big) | |||
" Simple The speed of light cannot be exceeded even by light xx Thus train traveling at light speed arrives at exactly the same time as the light emitted this assumes that the lights were not switched on before the train departs if so the light will be seen exactly that time before the train arrives However if the gravity of the train were to affect space time we have a differing scenario but that really does become complex xxx That's right the speed of light cannot be exceeded and remains unchanged for all observers. So when sat on the space train travelling at 99.99% lightspeed, light shines from its headlamp as normal and travels away from the train at the speed of light, as observed from the train. Forget the gravity stuff, it is another story." This Physics talk is so damned sexy! | |||
Reply privately (closed, thread got too big) | |||
" Simple The speed of light cannot be exceeded even by light xx Thus train traveling at light speed arrives at exactly the same time as the light emitted this assumes that the lights were not switched on before the train departs if so the light will be seen exactly that time before the train arrives However if the gravity of the train were to affect space time we have a differing scenario but that really does become complex xxx That's right the speed of light cannot be exceeded and remains unchanged for all observers. So when sat on the space train travelling at 99.99% lightspeed, light shines from its headlamp as normal and travels away from the train at the speed of light, as observed from the train. Forget the gravity stuff, it is another story." That's the point unless the train affects space time and local gravity the light will not shine away , the crux here is space time is the train moving relatively through it or warping it The speed of light is relative to space time gravity and not any other object thus an object not affecting or affected space time will see light differently Many stars are moving away from us however some relatively due to orbit are moving for a time rapidly towards us the speed of the light measured from these stars is the same regardless of there starting speed Once light is released it is a free agent moving through space time at , light speed If the train is moving through space time at the same speed then the light does not project forwards If the train is space time then me course it moves away at light speed I have little doubt that areas of space time move thus causing relative differences in observed light speeds However don't think a train would have sufficient mass to affect it's local space time or gravity and would not project light | |||
Reply privately (closed, thread got too big) | |||
" Simple The speed of light cannot be exceeded even by light xx Thus train traveling at light speed arrives at exactly the same time as the light emitted this assumes that the lights were not switched on before the train departs if so the light will be seen exactly that time before the train arrives However if the gravity of the train were to affect space time we have a differing scenario but that really does become complex xxx That's right the speed of light cannot be exceeded and remains unchanged for all observers. So when sat on the space train travelling at 99.99% lightspeed, light shines from its headlamp as normal and travels away from the train at the speed of light, as observed from the train. Forget the gravity stuff, it is another story. That's the point unless the train affects space time and local gravity the light will not shine away , the crux here is space time is the train moving relatively through it or warping it The speed of light is relative to space time gravity and not any other object thus an object not affecting or affected space time will see light differently Many stars are moving away from us however some relatively due to orbit are moving for a time rapidly towards us the speed of the light measured from these stars is the same regardless of there starting speed Once light is released it is a free agent moving through space time at , light speed If the train is moving through space time at the same speed then the light does not project forwards If the train is space time then me course it moves away at light speed I have little doubt that areas of space time move thus causing relative differences in observed light speeds However don't think a train would have sufficient mass to affect it's local space time or gravity and would not project light " Well, I think you're getting pretty mixed up here. Don't forget that anything that has mass has gravity and affects space time. The rest, it doesn't really make sense, sorry. | |||
Reply privately (closed, thread got too big) | |||
"Why do you lot get so angry. If you don't like what someone is posting why dont you trot on to the next post. Chill. There's a word. Tr........" | |||
Reply privately (closed, thread got too big) | |||
p.s. has that plane exploded yet? and how close to 175 are we? | |||
Reply privately (closed, thread got too big) | |||
" If the train is moving through space time at the same speed then the light does not project forwards If the train is space time then me course it moves away at light speed I have little doubt that areas of space time move thus causing relative differences in observed light speeds However don't think a train would have sufficient mass to affect it's local space time or gravity and would not project light " That's got a bit garbled, but the first bit is just wrong. Light always moves at light speed relative to the observer, no matter what. | |||
Reply privately (closed, thread got too big) | |||
| |||
Reply privately (closed, thread got too big) | |||
"That's got a bit garbled, but the first bit is just wrong. Light always moves at light speed relative to the observer, no matter what." I would have to say that light speed is never observed, it's too fast for our brains to perceive. all we see is the shadow of where it was... | |||
Reply privately (closed, thread got too big) | |||
"Should we all just head over to XKCD to carry on the discussion there ?" Nah, we will get to 175 soon then we can forget all about it for a few months until some Terry Thomas with a white cat posts the thread again | |||
Reply privately (closed, thread got too big) | |||
| |||
Reply privately (closed, thread got too big) | |||
| |||
Reply privately (closed, thread got too big) | |||
| |||
Reply privately (closed, thread got too big) | |||
| |||
Reply privately (closed, thread got too big) | |||
| |||
Reply privately (closed, thread got too big) | |||
"Should we all just head over to XKCD to carry on the discussion there ? Nah, we will get to 175 soon then we can forget all about it for a few months until some Terry Thomas with a white cat posts the thread again "That was me!! I was not expecting nearly 700 replies but it has been interesting!! I will not start it again if I am convinced what the correct answer is. | |||
Reply privately (closed, thread got too big) | |||
"Not all light travels at the speed of light... Er? Please explain this. All EM waves travel at the speed of light for the medium that they are in." I don't know, I didn't understand it...
The same website also states that there are 3 or 4 things faster than light but I didn't understand stand that either...
The only thing I know that is faster than light is dark... If you notice it's always dark before the light get there... | |||
Reply privately (closed, thread got too big) | |||
" Water is viscous and maybe as the jet ski pumps the hundreds of gallons of water out behind it, if there is a wall it will well up and flow back exerting forward force on the back of the jet ski. Can't see it happening with a jet and a blast wall though, with air. I can't see any mechanism for the force of the jet of water FROM the jet ski on the wall causing a force on the jet ski that the water jet came from. I'd like to understand how that could happen. Water is incompressible (to all intents and purposes) and so maybe you're right that the VOLUME of water being pumped into the space between the jet ski and the wall causes a rebound wave that pushes the jet ski. However this is not an effect caused by the jet of water. The jetskier is describing what he experiences in real life. So the thing is to explain why it could happen. It's not a 'jet' effect but is a secondary effect of it acting as a pump in a confined space." A pump in a confined space? Shouldn't that be in tje 'Stuck in a Lift' thread? | |||
Reply privately (closed, thread got too big) | |||
| |||
Reply privately (closed, thread got too big) | |||
"Bugger, I was just going to post the plane on a conveyor question as I love the arguing that ensues
"Thank heaven for small mercies. | |||
Reply privately (closed, thread got too big) | |||
"Bugger, I was just going to post the plane on a conveyor question as I love the arguing that ensues
"You could just post anything. Generally from around the fifth post someone is arguing or taking issue with something?
Having said that would a ling jumper in a treadmill at full blast be able to jump forward as far as they normally do? | |||
Reply privately (closed, thread got too big) | |||
"How can it? No forward motion= no airflow= no lift" The wheels aren't driving the plane forward, the engines are. The wheels would just be going twice as fast when the plane reached the required air speed. | |||
Reply privately (closed, thread got too big) | |||
"If it was possible to launch a plane off a conveyor belt, wouldnt they make smaller aircraft carriers? Well they do use some tricks to make aircraft carriers work with shorter runways, blast wall so the thrusters have something to push against, and a big elastic band to speed up launch, and catchers for landing (which can be a bigger problem) " Most significantly for this question, on UK carriers without catapults, you turn the carrier into the wind for launches to increase the airflow over the wings and shorten the take-off run. I've never flown of a US flat top in anything but a cab, but presume they still do the same. | |||
Reply privately (closed, thread got too big) | |||
"Most significantly for this question, on UK carriers without catapults, you turn the carrier into the wind for launches to increase the airflow over the wings and shorten the take-off run. I've never flown of a US flat top in anything but a cab, but presume they still do the same." The UK is much more ingenious than that, they built and paid for the aircraft carriers then cancelled the aircraft, so now they are floating roller skate parks | |||
Reply privately (closed, thread got too big) | |||
| |||
Reply privately (closed, thread got too big) | |||
| |||
Reply privately (closed, thread got too big) | |||
"The conveyor belt is designed to exactly match the speed of the wheels, moving in the opposite drection. Can the plane take off? Merry Christmas "NOT THIS THING AGEN......
Had enuf trubal with this larst time.
Yes it can take of !
https://m.youtube.com/watch?v=YORCk1BN7QY | |||
Reply privately (closed, thread got too big) | |||
"My take on it, for what its worth. Unless there is airflow over/under the wings then it aint gonna fly, seeing as flight requires lift, which is generated by the front edge of the wing travelling through air and creating lower pressure below the wing, and higher pressure above." Correct. But the conveyor belt can't stop the plane moving forward, as the planes wheels just free spin. So the planes engines would thrust it forwards, as normal. It would gain groundspeed and airspeed as normal and take off. It still needs the normal 1/2 mile of runway / conveyor belt. | |||
Reply privately (closed, thread got too big) | |||
| |||
Reply privately (closed, thread got too big) | |||
| |||
Reply privately (closed, thread got too big) | |||
| |||
Reply privately (closed, thread got too big) | |||
| |||
Reply privately (closed, thread got too big) | |||
"Bloody hell this is an old one! No it can’t "Oh yes it can. | |||
Reply privately (closed, thread got too big) | |||
| |||
Reply privately (closed, thread got too big) | |||
| |||
Reply privately (closed, thread got too big) | |||
"Bloody hell this is an old one! No it can’t
Oh yes it can."Early panto
Cmon boys and girls. “OH NO IT CANT”  | |||
Reply privately (closed, thread got too big) | |||
"Bloody hell this is an old one! No it can’t
Oh yes it can.
Early panto
Cmon boys and girls. “OH NO IT CANT” "Can this belt stop Santa's sled taking off? | |||
Reply privately (closed, thread got too big) | |||
| |||
Reply privately (closed, thread got too big) | |||
"Do we all agree that for the plane to move forward the wheels however infinitesimally, must have turned at a faster speed than the conveyor? S" Depends what is meant by the wheel. The wheel as a whole can move forward at 200mph and the conveyor backwards at 200mph. The tyres would be spinning at 400 mph equivalent. | |||
Reply privately (closed, thread got too big) | |||
| |||
Reply privately (closed, thread got too big) | |||
"Do we all agree that for the plane to move forward the wheels however infinitesimally, must have turned at a faster speed than the conveyor? S Depends what is meant by the wheel. The wheel as a whole can move forward at 200mph and the conveyor backwards at 200mph. The tyres would be spinning at 400 mph equivalent." Well, I'd say "matched" more meant if the diameter of the wheel is say four feet then for every forward rotation the conveyor moves back four feet. What I'm getting at is peeps stating thrust etc, some laws of physics, its hypothetical surely so if the person posing the questions says black is white then black is white for the question. If we agree that for that plane to move along the conveyor runway they would have to spin faster than the conveyor is moving backwards then all other facts are irrelevant because the questions says they do not, ever.. S | |||
Reply privately (closed, thread got too big) | |||
"Imagine a train going along a straight track at say 20 mph (it doesn't matter but a slow speed). A fly flies along the track in the opposite direction, lands on the front of the train and is then carried on the front of the train (alive not squished!) in the opposite direction. As the fly must have changed direction from forwards to backwadrds it must have stopped for an instant to do so; therefore as the fly was always in contact with the train; the train must have stopped as well? Over to you." if the train is constantly moving then the moment the fly stopped to change direction the space between the 2 objects would have got smaller and for the fly to land safely on the train it would jus about ya e to match the speed of the train so no the train did not necessarily stop | |||
Reply privately (closed, thread got too big) | |||
"Bloody hell this is an old one! No it can’t
Oh yes it can.
Early panto
Cmon boys and girls. “OH NO IT CANT”
Can this belt stop Santa's sled taking off?"Why are bringing the big guy into this
Unbelievable | |||
Reply privately (closed, thread got too big) | |||
"Do we all agree that for the plane to move forward the wheels however infinitesimally, must have turned at a faster speed than the conveyor? S Depends what is meant by the wheel. The wheel as a whole can move forward at 200mph and the conveyor backwards at 200mph. The tyres would be spinning at 400 mph equivalent. Well, I'd say "matched" more meant if the diameter of the wheel is say four feet then for every forward rotation the conveyor moves back four feet. What I'm getting at is peeps stating thrust etc, some laws of physics, its hypothetical surely so if the person posing the questions says black is white then black is white for the question. If we agree that for that plane to move along the conveyor runway they would have to spin faster than the conveyor is moving backwards then all other facts are irrelevant because the questions says they do not, ever.. S" It's written purposely to be confusing. But a conveyor can't stop a free spinning wheel. Also matching the speed of the wheel *to me* means if the wheel (ie at the bearing) moves forward at 100mph the belt moves back at 100mph. The plane still has forward motion. But it's down to interpretation of a purposely misleading / undefined question. The question is banned on many physics and university boards as a result. | |||
Reply privately (closed, thread got too big) | |||
"Do we all agree that for the plane to move forward the wheels however infinitesimally, must have turned at a faster speed than the conveyor? S Depends what is meant by the wheel. The wheel as a whole can move forward at 200mph and the conveyor backwards at 200mph. The tyres would be spinning at 400 mph equivalent. Well, I'd say "matched" more meant if the diameter of the wheel is say four feet then for every forward rotation the conveyor moves back four feet. What I'm getting at is peeps stating thrust etc, some laws of physics, its hypothetical surely so if the person posing the questions says black is white then black is white for the question. If we agree that for that plane to move along the conveyor runway they would have to spin faster than the conveyor is moving backwards then all other facts are irrelevant because the questions says they do not, ever.. S It's written purposely to be confusing. But a conveyor can't stop a free spinning wheel. Also matching the speed of the wheel *to me* means if the wheel (ie at the bearing) moves forward at 100mph the belt moves back at 100mph. The plane still has forward motion. But it's down to interpretation of a purposely misleading / undefined question. The question is banned on many physics and university boards as a result." | |||
Reply privately (closed, thread got too big) | |||
| |||
Reply privately (closed, thread got too big) | |||
"You do realise that on a jet plane the wheels arnt driven, it’s the jet engine that propels the plane. It’s the planes speed through the air that determines if it takes off not over the ground. " Exactly, unlike a train where the wheels provide the propulsion, I suspect that a train on a conveyor belt wouldn't be able to fly | |||
Reply privately (closed, thread got too big) | |||
" Look up the xkcd aeroplane treadmill blog post, and don't fall for this flamebait ever again " | |||
Reply privately (closed, thread got too big) | |||
| |||
Reply privately (closed, thread got too big) | |||
| |||
Reply privately (closed, thread got too big) | |||
| |||
Reply privately (closed, thread got too big) | |||
"The conveyor belt is designed to exactly match the speed of the wheels, moving in the opposite drection. Can the plane take off? Merry Christmas "Just taxi and turn the plane around so it's going the other way #sorted | |||
Reply privately (closed, thread got too big) | |||
| |||
Reply privately (closed, thread got too big) | |||
"Imagine a large plastic bucket with a handle on either side. If I stand in it and grab the handles, will I be able to lift the bucket off the ground? (CLUE -the answer begins with N)" do you mean can you lift yourself up ? I would say if you jump up you'd be able to lift the bucket off the ground. I'll try it later in a cardboard box | |||
Reply privately (closed, thread got too big) | |||
"Imagine a large plastic bucket with a handle on either side. If I stand in it and grab the handles, will I be able to lift the bucket off the ground? (CLUE -the answer begins with N)" Yes, if you pull hard enough. Your feet will rip through the bottom and the *bucket will lift off the ground* . You won't though | |||
Reply privately (closed, thread got too big) | |||
"Imagine a large plastic bucket with a handle on either side. If I stand in it and grab the handles, will I be able to lift the bucket off the ground? (CLUE -the answer begins with N)" Which is odd because I suspect that if you had a bar above your head you could lift your body weight. So either the bucket is heavy or your muscles only work in one direction | |||
Reply privately (closed, thread got too big) | |||
| |||
Reply privately (closed, thread got too big) | |||
| |||
Reply privately (closed, thread got too big) | |||
| |||
Reply privately (closed, thread got too big) | |||
"If you stand in a bucket you cannot lift yourself up or be moved by any other person or machine. FACT. " Not true, but in my experience it causes pain in the nose and blood to leek from lips... weird this science stuff isn't it | |||
Reply privately (closed, thread got too big) | |||
| |||
Reply privately (closed, thread got too big) | |||
