Question

Though friction opposes relative motion, yet in certain cases, friction is also the cause of motion. In fact, without friction, motion cannot be started, stopped or transferred from one body to the other.

Read the above passage and answer the following questions:

Give the direction of friction on front wheel and rear wheel of a bicycle when it is pedalled and when pedalling is stopped.

Answer 1

Dear Student

In bicycle, pedalling is done on rear wheel. This means that we try to rotate the rear wheel to move forward. The rear wheel pushes the ground backwards and gets the forward frictional force which pushes the bicycle forward.
The front wheel is being pushed forward (through the connecting rod between the rear and front wheels) which results in the backward frictional force on its tire which rotate it in the same direction as the rear wheel.