Can cycles work without friction?
Answers
Answer:
I shall try to explain the scenario when the cycle is initially at rest, and you are trying to bring it in motion by pedalling it.
Friction force is the force which opposes the relative motion or the tendency of relative motion.
The kinematics of front wheel and the rear wheel is different in terms of physics.
Rear wheel :
When you start pedalling the cycle, the real wheel gets a tendency to rotate in clockwise direction. So, if you observe closely, the tendency of the bottom most point of the rear wheel is to go backwards. Hence, friction opposes the tendency and starts acting in the forward direction. Let this frictional force be f1.
Front Wheel :
The front wheel is attached to the cycle by front fork. When the rear wheel sets in motion, the front fork [attached to the center of the front wheel] applies a force on the front wheel and coaxes it to slide forward. Hence the tendency of the front wheel is to move forward. So the friction starts acting in the backward direction. Let this frictional force be f2
Since the cycle is accelerating in the forward direction and there is no external force being applied to the cycle except for f1 and f2, hence f1 must be always greater than f2. In other words, friction acting on the rear wheel is always greater than front wheel. This is the reason why the rear wheel gets wear and tear more frequently that front wheel.