Assertion : When a bicycle is in motion, the force of friction exerted by the ground on the two wheels is always in forward direction. Reason : The frictional force acts only when the bodies are in contact

Options

A. If both assertion and reason are true and the reason is the correct explanation of the assertion
B. If both assertion and reason are true but reason is not the correct explanation of the assertion.
C. If assertion is true but reason is false.
D. If assertion is false but reason is true.

Answer

D

Explanation

When a bicycle is in motion, two cases may arise :
(i) When the bicycle is being pedalled. In this case, the applied force has been communicated to rear wheel. Due to which the rear wheel pushes the earth backwards. Now the force of friction acts in the forward direction on the rear wheel but front wheel moves forward due to inertia, so force of friction works on it in backward direction
(ii) When the bicycle is not being pedalled :
In this case both the wheels move in forward direction, due to inertia. Hence force of friction on both the wheels acts in backward direction.