Answer
18,000
Why?
KE=(1/2)(2000)(18)
Ke=18,000
I did the quiz, (D) "The total kinetic and potential energies of its particles" is correct.
Newton's third law: If an object A exerts a force on object B, then object B must exert a force of equal magnitude and opposite direction back on object A. This law represents a certain symmetry in nature: forces always occur in pairs, and one body cannot exert a force on another without experiencing a force itself.