Question

In which of the following situations has the energy of the object been increased?

A hammer thrower spins around while preparing to release the hammer.

A horse moves horizontally while a circus performer jumps vertically on its back.

A boy pushes a lawn mower forward by pushing at a downward angle on the handle.

A soldier runs forward, while holding a rifle above his head.

Answer 1

let me think about this for a moment

Answer 2

Okay Thanks

Answer 3

This question is very vague.
I'm going to number the situations

1) The rotational kinetic energy of the person spinning increases.
3)The boy, assuming he starts from rest, pushes the lawn mower forward at a velocity v, so his kinetic energy increases.
4) The soldier's energy, assuming he has been running at the same velocity, does not change in kinetic energy; it stays the same.

These three situations all involve only one person in the system.

2) The horse is moving so it has a kinetic energy. The circus performer, an outside force, exerts a force on the horse, therefore I believe tit would be the second one but let me ask someone.

Answer 4

@broken_symmetry
could you verify my response?

Answer 5

I'd say the hammer one, but the question doesn't make much sense to me.

What is the "object" with the horse/circus performer one?
Energy increased from when?

Answer 6

thanks!