Answer
a. Yes
b. No
c. Yes
Work Step by Step
a. If an object is moving in a circle at constant speed, there is a net nonzero force acting on it at all times (the centripetal force, directed toward the center). However, its speed does not change.
b. A nonzero force means that there is a nonzero acceleration. By the definition of acceleration, the velocity must change. (In the case of an object moving in a circle at constant speed, the direction is continuously changing.)
c. If an object is in uniform circular motion, the speed stays the same, so there is no change in its kinetic energy.
