Picture the glider with gear wheels - and the treadmill with matching gear tread. When the planes touches they mesh perfectly.
It doesnt matter what speed it comes in - wheel bearings frictionless, perfect contact i.e. no skip or slip of the wheel - it will stop do you concur?
Now you're changing the parameters.... again. <img src="/forums/images/graemlins/lol.gif" alt="" /> In this case, the gears on the plane's tread will mesh with the teeth on the treadmill. The only way to gain sychronization would be to have the plane's wheels driven. The drive mechanism would have the effect of locking the wheel to the treadmill and the result would be a broken gear as the assembly shears from the airplane on impact. The gear would stop, but the rest of the plane would continue down the treadmill runway. If the gear was strong enough, everything would stop if the force applied by the treadmill equalled the force of the plane..... BUT.... that scenario would not be considered WHEELS..... it's now GEARS!!
Picture the glider with gear wheels - and the treadmill with matching gear tread. When the planes touches they mesh perfectly.
It doesnt matter what speed it comes in - wheel bearings frictionless, perfect contact i.e. no skip or slip of the wheel - it will stop do you concur?
No, the glider won't stop - wheels or no wheels. All that will happen with a glider on wheels, is the wheels will now turn twice as fast when the treadmill matches the glider's speed in reverse direction.... if the treadmill direction and speed is the same as the glider, the wheels don't turn at all.
Momentum is mass times velocity correct?
So the plane 100 lbs.
Velocity of the plane matches velocity of treadmill. They cancel out. Zero.
100x0 is zero - no momentum.
No momentum means no forward motion.
Right there is where you're getting wrapped around the axle, Phil. In order for energy to transfer, force must be applied by one thing acting on another. If the treadmill had a 20' high steel wall mounted to the tread that moved as a part of the tread in the opposite direction to the plane's travel.... and if the mass of the wall was the same as the plane.... and if the wall was moving at the same speed as the plane.... and if the treadmill decoupled from its drive mechanism just before impact (better if the wall decoupled from the tread via frictionless bearings)..... and if the plane flew into the wall......... then yes, energy transfer would balance and everything would come to an instant stop. But what you have in the original parameters is an inability for the treadmill to transfer force to the plane equal to the plane's thrust because the bearings allow the wheels to turn.
Think of it like getting stuck on slick wet grass or clay - no matter how fast you spin the wheels, you can't transfer power and when you can't transfer power laterally, no movement can be expected.
You should ponder why airplanes have wheels....... one reason is to prevent (or control) energy transfer on landing. Otherwise, the event becomes a crash where the energy of the flying airplane is absorbed by the earth and the resulting force destroys the plane and kills the occupants. The second reason is to negate frictional forces between the airplane and the ground.... to allow the thrust of the airplane's engine to build momentum and move the plane over the ground at an increasing rate of speed in order to achieve enough air speed over the wing to generate the amount lift needed for takeoff.
Frank
