Question

A ball dropped form a height of 10 m only bounces to a height of 5m. Which of the following statements is valid for this situation?

A. Kinetic energy is conserved.

B. Mechanical energy is conserved.

C. Gravitational potential energy is conserved.

D. Elastic potential energy is conserved.

E. None of these are conserved.

I think the answer is E.

What laws or principals apply to make it E? Could you also make a diagram explaining it.

Answer 1

YES the answer is E because if the energy is conserved and no dissipative forces act the ball which was dropped from a height of 10m should rise back to 10m,but it rose till 5m only.Some of the energy is lost due to work done . non conservative disipative forces like air resistance friction .The principle that can be applied in case of E is total change in mechanical energy that is kinetic energy and potential energy is equal to work done by non conservative plus external plus conservative forces .Change in kinetic energy is equal to work done bykinetic friction

answered by: anonymous