Originally posted by: spidey07
Originally posted by: randay
for fucks sake why is this so hard to understand?
A TREADMILL CANNOT STOP AN AIRPLANE FROM MOVING FORWARD.
Why not?
It's already been shown that it can move it backwards. Seriously, just think about it it. If the treadmill can move a plane backwards then all you have to do is speed it up to move it backwards with more force. As long as this is equal to the thrust of the plane - the plane isn't going anywhere.
Originally posted by: Tweak155
THIS IS FOR ALL THOSE THAT THINK THE AIRPLANE WILL NOT TAKE OFF (offering a different way to prove to yourself that you're wrong):
Lets say an airplane is flying and is about to land. It lands on this conveyor belt that is moving the opposite direction the plane is traveling.
Do you REALLY believe that it is physically possible for the airplane to land on this conveyor belt and all of a sudden and sit still? This would require not moving forward an inch upon landing. I'll let you set the speed of the plane and the speed of the belt. If your numbers are outrageous, then I am allowed to insert that frictionless bearings and tire to conveyor belt friction is 0, which is also outrageous.
Car != airplane.
I realize this isn't the same scenario, but it helps illustrate that the airplane does not use the wheels/axles to move forward.
Originally posted by: Tweak155
THIS IS FOR ALL THOSE THAT THINK THE AIRPLANE WILL NOT TAKE OFF (offering a different way to prove to yourself that you're wrong):
Lets say an airplane is flying and is about to land. It lands on this conveyor belt that is moving the opposite direction the plane is traveling.
Do you REALLY believe that it is physically possible for the airplane to land on this conveyor belt and all of a sudden and sit still? This would require not moving forward an inch upon landing. I'll let you set the speed of the plane and the speed of the belt. If your numbers are outrageous, then I am allowed to insert that frictionless bearings and tire to conveyor belt friction is 0, which is also outrageous.
Car != airplane.
I realize this isn't the same scenario, but it helps illustrate that the airplane does not use the wheels/axles to move forward.
Originally posted by: smack Down
Originally posted by: Tweak155
THIS IS FOR ALL THOSE THAT THINK THE AIRPLANE WILL NOT TAKE OFF (offering a different way to prove to yourself that you're wrong):
Lets say an airplane is flying and is about to land. It lands on this conveyor belt that is moving the opposite direction the plane is traveling.
Do you REALLY believe that it is physically possible for the airplane to land on this conveyor belt and all of a sudden and sit still? This would require not moving forward an inch upon landing. I'll let you set the speed of the plane and the speed of the belt. If your numbers are outrageous, then I am allowed to insert that frictionless bearings and tire to conveyor belt friction is 0, which is also outrageous.
Car != airplane.
I realize this isn't the same scenario, but it helps illustrate that the airplane does not use the wheels/axles to move forward.
Sorry but you are just plan wrong when you say car != plane. Both would perform identically if they had the same mass and the wheels had the same moment of inertia.
I know I know plane thrust isn't at the wheels, and the plane wheels are "free spining" All wheels are "free spinning" if a wheel can't spin then it isn't a wheel it is just a circle and where a force is applied is irrelevant in a solid body. I can move a force to any point without changing the problem.
Originally posted by: spidey07
Originally posted by: Tweak155
THIS IS FOR ALL THOSE THAT THINK THE AIRPLANE WILL NOT TAKE OFF (offering a different way to prove to yourself that you're wrong):
Lets say an airplane is flying and is about to land. It lands on this conveyor belt that is moving the opposite direction the plane is traveling.
Do you REALLY believe that it is physically possible for the airplane to land on this conveyor belt and all of a sudden and sit still? This would require not moving forward an inch upon landing. I'll let you set the speed of the plane and the speed of the belt. If your numbers are outrageous, then I am allowed to insert that frictionless bearings and tire to conveyor belt friction is 0, which is also outrageous.
Car != airplane.
I realize this isn't the same scenario, but it helps illustrate that the airplane does not use the wheels/axles to move forward.
See - this is why people can't understand the physics involved. Hell, I was pretty good back when I flew RC planes so the principle of flight is so simple to me. I totally understand.
The question is a paradox. If you can't understand how and why the treadmill can retard the plane then you FAIL at physics.
Still everybody that believes a takeoff plane fails at physics. Imagine the original constraints of the problem and make your point.
Stop trying to imagine it in your mind and do the math.
Originally posted by: spidey07
Originally posted by: Tweak155
THIS IS FOR ALL THOSE THAT THINK THE AIRPLANE WILL NOT TAKE OFF (offering a different way to prove to yourself that you're wrong):
Lets say an airplane is flying and is about to land. It lands on this conveyor belt that is moving the opposite direction the plane is traveling.
Do you REALLY believe that it is physically possible for the airplane to land on this conveyor belt and all of a sudden and sit still? This would require not moving forward an inch upon landing. I'll let you set the speed of the plane and the speed of the belt. If your numbers are outrageous, then I am allowed to insert that frictionless bearings and tire to conveyor belt friction is 0, which is also outrageous.
Car != airplane.
I realize this isn't the same scenario, but it helps illustrate that the airplane does not use the wheels/axles to move forward.
See - this is why people can't understand the physics involved. Hell, I was pretty good back when I flew RC planes so the principle of flight is so simple to me. I totally understand.
The question is a paradox. If you can't understand how and why the treadmill can retard the plane then you FAIL at physics.
Still everybody that believes a takeoff plane fails at physics. Imagine the original constraints of the problem and make your point.
Stop trying to imagine it in your mind and do the math.
Originally posted by: smack Down
Sorry but you are just plan wrong when you say car != plane. Both would perform identically if they had the same mass and the wheels had the same moment of inertia.
I know I know plane thrust isn't at the wheels, and the plane wheels are "free spining" All wheels are "free spinning" if a wheel can't spin then it isn't a wheel it is just a circle and where a force is applied is irrelevant in a solid body. I can move a force to any point without changing the problem.
Question for you two: What if we assume that the wheels are connected to the axles by perfectly frictionless bearings? Can the conveyor retard the airplane's forward movement then?Originally posted by: spidey07
See - this is why people can't understand the physics involved. Hell, I was pretty good back when I flew RC planes so the principle of flight is so simple to me. I totally understand.
The question is a paradox. If you can't understand how and why the treadmill can retard the plane then you FAIL at physics.
Still everybody that believes a takeoff plane fails at physics. Imagine the original constraints of the problem and make your point.
Stop trying to imagine it in your mind and do the math.
Actually, quite the opposite. If the brakes were on such that the wheels could no turn, then the plane would slide across the treadmill until it gained enough speed and take off. The treadmill would never move because the wheels are locked and thus never violate the constraint.Originally posted by: Throckmorton
The only way the plane wouldn't take off would be if the brakes were on.Originally posted by: NanoStuff
Yes sir captain stupid.Originally posted by: JujuFish
I can't believe this argument is still going on. The plane takes off.
Originally posted by: spidey07
Stop trying to imagine it in your mind and do the math.
A thought experiment commonly cited in discussions of this question is to imagine you're standing on a health-club treadmill in rollerblades while holding a rope attached to the wall in front of you. The treadmill starts; simultaneously you begin to haul in the rope. Although you'll have to overcome some initial friction tugging you backward, in short order you'll be able to pull yourself forward easily.
As you point out, one problem here is the wording of the question. Your version straightforwardly states that the conveyor moves backward at the same rate that the plane moves forward. If the plane's forward speed is 100 miles per hour, the conveyor rolls 100 MPH backward, and the wheels rotate at 200 MPH. Assuming you've got Indy-car-quality tires and wheel bearings, no problem. However, some versions put matters this way: "The conveyer belt is designed to exactly match the speed of the wheels at any given time, moving in the opposite direction of rotation." This language leads to a paradox: If the plane moves forward at 5 MPH, then its wheels will do likewise, and the treadmill will go 5 MPH backward. But if the treadmill is going 5 MPH backward, then the wheels are really turning 10 MPH forward. But if the wheels are going 10 MPH forward . . . Soon the foolish have persuaded themselves that the treadmill must operate at infinite speed. Nonsense. The question thus stated asks the impossible -- simply put, that A = A + 5 -- and so cannot be framed in this way. Everything clear now? Maybe not. But believe this: The plane takes off.
Originally posted by: Cerpin Taxt
Originally posted by: smack Down
Sorry but you are just plan wrong when you say car != plane. Both would perform identically if they had the same mass and the wheels had the same moment of inertia.
I know I know plane thrust isn't at the wheels, and the plane wheels are "free spining" All wheels are "free spinning" if a wheel can't spin then it isn't a wheel it is just a circle and where a force is applied is irrelevant in a solid body. I can move a force to any point without changing the problem.
Question for you two: What if we assume that the wheels are connected to the axles by perfectly frictionless bearings? Can the conveyor retard the airplane's forward movement then?Originally posted by: spidey07
See - this is why people can't understand the physics involved. Hell, I was pretty good back when I flew RC planes so the principle of flight is so simple to me. I totally understand.
The question is a paradox. If you can't understand how and why the treadmill can retard the plane then you FAIL at physics.
Still everybody that believes a takeoff plane fails at physics. Imagine the original constraints of the problem and make your point.
Stop trying to imagine it in your mind and do the math.
Originally posted by: bdude
Let me see now...
F=ma
Normal Force pointing straight up. Consider the horizontal forces. Engine pointing ----> thataway.
Ok, goggles check, gear check...
Turn on the engines!
...
Good, ok engines powering up. 10%.Starting to lurch forward.
Time to read STR8 Dope.
A thought experiment commonly cited in discussions of this question is to imagine you're standing on a health-club treadmill in rollerblades while holding a rope attached to the wall in front of you. The treadmill starts; simultaneously you begin to haul in the rope. Although you'll have to overcome some initial friction tugging you backward, in short order you'll be able to pull yourself forward easily.
As you point out, one problem here is the wording of the question. Your version straightforwardly states that the conveyor moves backward at the same rate that the plane moves forward. If the plane's forward speed is 100 miles per hour, the conveyor rolls 100 MPH backward, and the wheels rotate at 200 MPH. Assuming you've got Indy-car-quality tires and wheel bearings, no problem. However, some versions put matters this way: "The conveyer belt is designed to exactly match the speed of the wheels at any given time, moving in the opposite direction of rotation." This language leads to a paradox: If the plane moves forward at 5 MPH, then its wheels will do likewise, and the treadmill will go 5 MPH backward. But if the treadmill is going 5 MPH backward, then the wheels are really turning 10 MPH forward. But if the wheels are going 10 MPH forward . . . Soon the foolish have persuaded themselves that the treadmill must operate at infinite speed. Nonsense. The question thus stated asks the impossible -- simply put, that A = A + 5 -- and so cannot be framed in this way. Everything clear now? Maybe not. But believe this: The plane takes off.
Wooo! Liftoff.
Originally posted by: her209
With regard to the traction of the wheels, if we assume that 100% traction is maintained, then the F(engine) < u(static) * N where N is the normal force of the plane, i.e. weight of the plane. Are we to assume (in the real world) that the u(static) is so high such that F(engine)(max) / N will never > u(static)? I don't think you can.
Threfore, once F(engine) > u(static) * N, then this means slippage occurs in which case we must use u(kinetek) * N to calculate the amount of kinetic friction exterted on the wheel.
Finally, this means that the plane CAN move forward without breaking the constraint that the rotational velocity has to be equal to the treadmill's velocity and THE PLANE TAKES OFF.
Originally posted by: bignateyk
Originally posted by: Squisher
As I posted in the other two threads:
If I'm flying a plane at 200mph and I hang out of it and affix a treadmill to the wheels which cause the wheels to spin at a rate that would generate a speed of 200mph backwards. Will the plane fall out of the sky?
no, because the plane is still moving at a speed relative to the ground, which will cause air to flow over the wings and the plane to have lift.
If the treadmill is on the ground and the plane has a ground speed of 0mph, then there will be no air flow over the wings, and no lift.
Originally posted by: bignateyk
Originally posted by: zanejohnson
holy crap, i thought the people who didnt think it would take off were just joking...
who could be that stupid lol...
of course the plane will take off.
the force that makes a plane take off is the lift, from air rushing under the wings, "lifting" it up....
no matter how fast the conveyer belt moves the thrust from the jets/propellors will STILL push the plane forward, because a plane is not pushed with a driveshaft to the wheels like a car, the wheels have nothing to do with the plane taking off.
it would take very little thrust to keep the plane stationary on the treadmill, and just a little more to push it forward on the treadmill.... and as soon as it starts moving forward air will flow beneath the wings, applying lift.
The whole point of the problem is that the plane is stationary on the treadmill with respect to the ground. No shit it will take off if it starts moving foward on the treadmill. If it is just cruising along at the same speed as the treadmill and not moving foward, there will be no air moving over the wings, and it will have no lift. It wont take off. There will be thrust, but just because there is thrust doesnt mean there is lift.
Originally posted by: bignateyk
Originally posted by: Squisher
As I posted in the other two threads:
If I'm flying a plane at 200mph and I hang out of it and affix a treadmill to the wheels which cause the wheels to spin at a rate that would generate a speed of 200mph backwards. Will the plane fall out of the sky?
no, because the plane is still moving at a speed relative to the ground, which will cause air to flow over the wings and the plane to have lift.
If the treadmill is on the ground and the plane has a ground speed of 0mph, then there will be no air flow over the wings, and no lift.
Thank you for proving to us you have no idea what you are talking about.Originally posted by: smack Down
Yes of course it can. If you wish to see that for yourself go get a wheel and put it on a treadmill. Turn on the treadmill and watch the wheel come back at you. Use a wheel with no axle ans you will have almost frictionless bearings.Originally posted by: Cerpin Taxt
Question for you two: What if we assume that the wheels are connected to the axles by perfectly frictionless bearings? Can the conveyor retard the airplane's forward movement then?
Originally posted by: smack Down
Originally posted by: her209
With regard to the traction of the wheels, if we assume that 100% traction is maintained, then the F(engine) < u(static) * N where N is the normal force of the plane, i.e. weight of the plane. Are we to assume (in the real world) that the u(static) is so high such that F(engine)(max) / N will never > u(static)? I don't think you can.
Threfore, once F(engine) > u(static) * N, then this means slippage occurs in which case we must use u(kinetek) * N to calculate the amount of kinetic friction exterted on the wheel.
Finally, this means that the plane CAN move forward without breaking the constraint that the rotational velocity has to be equal to the treadmill's velocity and THE PLANE TAKES OFF.
Yes, assume the wheels never lose traction.
Originally posted by: DeathBUA
and especially ATOT since we have such hot debates about the plane on a conveyor.
Originally posted by: her209
Thank you for proving to us you have no idea what you are talking about.Originally posted by: smack Down
Yes of course it can. If you wish to see that for yourself go get a wheel and put it on a treadmill. Turn on the treadmill and watch the wheel come back at you. Use a wheel with no axle ans you will have almost frictionless bearings.Originally posted by: Cerpin Taxt
Question for you two: What if we assume that the wheels are connected to the axles by perfectly frictionless bearings? Can the conveyor retard the airplane's forward movement then?
Originally posted by: her209
Originally posted by: smack Down
Originally posted by: her209
With regard to the traction of the wheels, if we assume that 100% traction is maintained, then the F(engine) < u(static) * N where N is the normal force of the plane, i.e. weight of the plane. Are we to assume (in the real world) that the u(static) is so high such that F(engine)(max) / N will never > u(static)? I don't think you can.
Threfore, once F(engine) > u(static) * N, then this means slippage occurs in which case we must use u(kinetek) * N to calculate the amount of kinetic friction exterted on the wheel.
Finally, this means that the plane CAN move forward without breaking the constraint that the rotational velocity has to be equal to the treadmill's velocity and THE PLANE TAKES OFF.
Yes, assume the wheels never lose traction.
LOL, this was not part of the original assumptions. Now it is?
Originally posted by: JohnOfSheffield
Originally posted by: DeathBUA
From Discovery Channel
Jamie and Adam take wing to test if a person with no flight training can safely land an airplane and if a plane can take off from a conveyor belt speeding in the opposite direction. Tory, Grant, and Kari jump on some Hollywood-inspired skydiving myths.
So despite being in TV guide and on discoverychannel.com that they would do plane on a conveyor belt discovery channel punk'd the entire internet, and especially ATOT since we have such hot debates about the plane on a conveyor. I must say I was highly disappointed.
Damn you discovery and damn you mythbusters!
If the conveyor belt is moving fast enough it will keep the plane in one place, no air passing the wings means no lifting power.
If you are not insane in the membrane you get this without a test.
Friction of wheels moving backwards at the same speed that the plane is propelled forwards means that the plane cannot move, it's as simple as shit and if you don't get it, you're retarded and i don't mean that in like "less knowledgeable" i really mean that you are fucked up in the skull in a way too serious to repair.