Question

What is the potential energy of a 3 kilogram-ball that is on the ground?

Answer 1

The answers zero because it is on the ground there's no way it can move without an external force.

Answer 2

The answer is 0
potential energy= mass• gravity (9.8m/s)• height.
Your mass 3kg. I believe your need to convert this to grams (3000g) and then multiply by 9.8. Since your height is 0 because the ball is on the ground then your potential energy is 0