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How does a wheel actually work in terms of physics?
A conceptual question ... imagine a car moving right to left as I look at it. The engine, gears, differential, and axle are applying a torque to the back wheels which rotate anti-clockwise as I look at it. If I look at the point of contact with the ground, the tyre is moving left to right, so there is a friction force acting right to left. This friction force is what is accelerating the car. If there was no friction, the tyre would spin with no forward force and just slip. So ... if I had a perfect frictionless drive train and no air resistance, friction would perpetually accelerate the car! Once you started a wheeled vehicle moving in sych conditions, how would it ever slow down? The only thing I can think of is that the normal force woukd act to slow the car since the tyre is not 100% rigid. Is my thinking wrong?!
In *such* conditions ...
Thanks all for your answers. It just seems strange that a friction force in this case would accelerate rather than decelerate a wheeled vehicle!
5 Answers
- ?Lv 79 months agoFavorite Answer
This is Newton's first law. Approximated by a space ship. The only way we know to accelerate that ship ( or to brake it) is by giving momentum to the fuel that it is carrying. Conservation of momentum means that throwing the fuel at high speed in one direction accelerates the rocket in the other direction.
- Anonymous6 months ago
I gave another hint to the answer to the riddle
- Anonymous7 months ago
The caveman who created the first wheel, only had one, and no motor and FICTION hadnt been invented, so I'm thinking when he faced this question, he probably just hit it with his club, and it cracked and broke because it was stone, but then he and his buddies got stoned, smoking mammoth dung.
- PhilomelLv 79 months ago
You have given friction to the tires to move the car so you have given friction to the tires to stop the car with brakes.
- ?Lv 79 months ago
The friction force is a reaction to the torque delivered to the tire by the engine. The engine only has so much fuel, when it runs out, the torque fades away, and the friction force with it. No perpetual motion machine here.
