Answer:

Explanation:
The period of a physical pendulum is:



The length of the leg is approximately the height of the person:

The period is:


B. moving electric charges, hope this helps :)
On the change in potential energy
Answer:
Zero
Explanation:
It is given that,
A person swims to the other end of a 20m long pool and back.
We need to find his displacement.
Displacement = shortest path covered
He reaches at the same position as from where he has started. It means the shortest path covered is equal to 0 i.e. his displacement is zero.