On a frictionless tabletop, a force is applied to an object: the object's velocity is horizontal and the force is perpendicular to the tabletop. Which of the following is true?
A) The applied force is friction.
B) The total energy of the object does not change.
C) There cannot be more than one force on the object.
D) The force does work on the object.

Question

Quizplus · Accepted Answer

Since the force is perpendicular to the direction of motion (and assuming it does not cause the object to leave the surface), it does not do work on the object, meaning the object's kinetic energy and thus total mechanical energy does not change.

On a Frictionless Tabletop, a Force Is Applied to an Object