Question

What must be true of a force that causes an object to move in a circular motion?

It acts parallel to the velocity and is directed toward the center of the circle.
It acts parallel to the velocity and is directed away from the center of the circle.
It acts perpendicular to the velocity and is directed toward the center of the circle.
It acts perpendicular to the velocity and is directed away from the center of the circle.

Answer 1

It acts perpendicular to the velocity and is directed toward the center of the circle.

Explanation: For circular motion the acceleration (and thus net force) must be centripetal—pointing toward the center—while the velocity is tangential, so the force is perpendicular to the velocity.