why the brakes of a car gets hotter than the brakes of a bicycle?

Frictional force

Explanation:

The brakes of a car gets hotter than the brakes of a bicycle because more frictional force is expended in applying the brake on a car than a bicycle.

To brake a car, the concept of friction is usually adopted. Two surfaces that increases friction when they come in contact are used in braking.

Frictional force is a force that resists the motion of a body. This forces helps to have grasp of motion.

A car requires more resistance to motion to break it because it have more more mass and other component motions parameters.

A bicycle is lighter and will require little friction.

Some of the frictional force applied is converted to heat energy. The amount of this energy expended is proportional to the frictional force.

Explanation:

It is mechanical energy because you are pushing the doorknob to the right you are manually doing it