Question

A ball bouncing off obeys:
A)LAW OF CONSERVATION OF MOMENTUM
B)LAW OF CONSERVATION OF ENERGY
C)DOES NOT OBEY LAW OF CONSERVATION OF ENERGY
D)DOES NOT OBEY LAW OF CONSERVATION OF MOMENTUM
plz give the answer with explanation.

Answer 1

Answer:

C) Doesn't obey law of conservation of energy

Explanation:

If the ball is performing perfectly elastic collision with the ground, then it will follow law of conservation of momentum.

However, if the ball performs inelastic collision, then it follows law of conservation of momentum in a direction perpendicular to it's normal with ground.

Moreover, the ball follows the equation mv = emv' in the direction of it's bouncing, where e is the coefficient of restitution.

Since the ball will always have some kind of non-conservative forces, so it won't follow law of conservation of energy.

Answer 2

A ball bouncing off obeys the Law of conservation of energy. Option(B) is the correct answer.

• When a ball is dropped from some height, the only force it experiences is the gravitational pull. The ball is moving so it will have some kinetic energy. When this ball reaches the ground, its kinetic energy gets converted into stored energy also known as potential energy. Now, by Newton's third law of motion, the ground will provide a push to the ball and convert its potential energy into kinetic energy and the ball will bounce off. Therefore, the total energy of the system remains the same. It follows the Law of conservation of energy.
• The Law of conservation of momentum is only applicable in elastic collisions where no external force is being exerted on the ball and the ball bounces off to the same height from which it was dropped. That is not possible as kinetic energy gets converted into other forms of energy.

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