Question

What kind of energy does the river water possess?



a river running through the woods.
It has no kinetic energy, just potential energy because it is going over a small waterfall.
Water has a special kind of water kinetic energy that comes from the water molecules themselves.
It possesses kinetic energy because it is moving.
Water possesses mechanical energy that only consists of the kinetic energy the water possesses, there is no potential energy present at all.

Answer 1

Correct answer: "It possesses kinetic energy because it is moving."

Explanation: the bulk motion of the river gives it macroscopic kinetic energy (½mv²). If the water is above a lower elevation (e.g. before a waterfall) it also has gravitational potential energy (mgh). Note that the random motion of molecules is thermal (internal) energy, not a separate "water kinetic energy" in the sense the second option suggests.