If one had spinning rims on their car, what would be the best way to make them spin the longest when the car was stopped. Friction reduction aside, we all know that.
Would it be best to gain maximum speed and then slam on the brakes, or maximum speed and decelerate quickly but not drastically? I tend to think the former, but I think such a sudden stop might jar the rim into slowing because of all the inertial force or momentum being exerted on the center of the hub.
W/o friction, the rims would never start spinning in the first place, nor would they ever stop once they got started…
Would it be best to gain maximum speed and then slam on the brakes, or maximum speed and decelerate quickly but not drastically? I tend to think the former, but I think such a sudden stop might jar the rim into slowing because of all the inertial force or momentum being exerted on the center of the hub.
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Assuming there was only a small amount of friction, and that the friction was independent of the speed of rotation, I would expect there would be a slightly longer spin of the inner rims if you decelerated slowly. The movement of the outer rims, however slow, would still be imparting some force on the rims, adding to the spin, if even just slightly.
Well I know that. I just didn’t want the first reply to be “in order to maximize spinning, you must reduce the friction”, that part seems rather obvious.
I did like your answer though, it’s along the same lines as what I was thinking. Thanks.
I probably worded it a bit incorrectly, though. If you come to a complete stop, you’ll be exerting a stopping (frictional) force on the inner rims which will eventually cause them to stop. If you decelerate slowly, you’ll still be exerting a net stopping force, but that force will be less since the outer wheels are still spinning in the same direction as the inner rims.
You might also cause the inner rims (or the ball bearings between the rims) to heat up and expand more if you stop suddenly and that WOULD cause the frictional forces to increase.
Without friction, without inertia, without envy, without bling, no one, anywhere, would give any part of any rat whether you spent six months income on a mechanical device to impress your next-door neighbor. The goals of your life are seldom skin deep.
(Three hours later,) Uh, yeah, that’s where I fell asleep. What was the question? :smack:
I just didn’t want the first reply to be “in order to maximize spinning, you must reduce the friction”, that part seems rather obvious.