Originally posted by: smack Down
Originally posted by: jmmtn4aj
Originally posted by: smack Down
Originally posted by: jmmtn4aj
Originally posted by: smack Down
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?
So you think if I put a wheel on a treadmill it will just stay put?
Good god man, an undercarriage with frictionless bearings does NOT equal an unattached wheel! Jesus!
What happens to the forward force exerted on the wheel by the axle? Remove the axle and the force is gone, obviously.
Isn't this high school level physics?
My high school physics included a chapter on the fact that forces added. If the wheels would move backwards with no undercarriage attached then they would move backwards with an undercarriage attached with frictionless bearings.
When you remove the axle, you remove the axis of rotation, meaning whatever happens with the bearings stop mattering. without the axis of rotation, the wheel becomes just another object on a moving surface. Without an axle, frictional contact between the tire surface and the treadmill causes a horizontal force in the direction that the treadmill is moving. Sure, it might rotate if the treadmill accelerates fast enough, but that's because it's a round object and hence is inherent unstable. Place a tall block in it's place and if the acceleration is fast enough, it falls.
And it still doesn't not equate to an undercarriage with frictionless bearings. An undercarriage with frictionless bearings still provides and axis of rotation allowing the frictional force between the tire surface and treadmill to be converted to rotational motion, acting as torque, instead of moving the entire wheel back. Frictionless simply means no force is generate in the housing where the axle joins to the wheel. Friction in the bearing causes resistance to the wheels rotation. Resistance means the wheels RESIST rotation, meaning a horizontal force is generated even before it reaches the axle-wheel assembly, meaning it's like the free wheel (albeit on a negligible scale) where the wheels resistance to spinning creates a resultant force that tries to move the entire wheel back, and anything connected to it. Frictionless bearings won't have resistance to rotation, so no resultant force parallel to the ground is created, but it still has to spin around a point first.
God, that didn't really make sense. Tomorrow guys.
You know why it didn't make sense because it is wrong. Just as mass has a resistance to accelerating it also has a resistance to rotation. Both with and with out the axle the wheel has the same axis of rotation.
The fact the wheel moves backwards means it does NOT have an axis of rotation, how on earth can it be the same?
An axle exerts forward force to counter the backwards force created by frictional force between the tire surface and treadmill surface. Frictionless bearings only means the lack of an additional force OVER that, in the form of moments about the axle, which translates into an additional rearward force. When the wheel rotates forwards, frictional force acts in the opposite direction, backwards. Viewed from the upright right side, the wheel is rotating clockwise producing a counter clockwise frictional force, a CCW moment. If assume smooth bearings, thus zero frictional coefficient, that CCW force is gone, and thus a moment about the axle, but NOT the forwards acting force exerted by the axle to counter frictional force caused by the wheels mass and the treadmill surface, that force obviously still has to be there don't you think? By removing the axle you remove that force as well.
Surely no one is really so simple as to think wheels with frictionless contact with the axle are the same as wheels not attached to the axle at all. Frictionless bearings are assumed by taking frictional coefficients to be zero, NOT by removing mass and definitely NOT by removing a surface altogether. Doing either of those fucks up the entire model altogether. It's like testing a plane in a wind tunnel without wings just to remove friction caused by wing skin surface. Jesus christ.
Are you one of those flat earth society guys?