Which term describes a force away from the center of rotation?

• A. Centrifugal force
• B. Centripetal force
• C. Threshold braking
• D. Friction

Answer: (A)

Describing circular motion, the outward-acting force in a rotating frame is centrifugal force. It arises because inertia wants to move in a straight line while the path curves, so in a rotating reference frame we describe an apparent push away from the center. In the actual, non-rotating frame, the inward force toward the center—the centripetal force—is what keeps the object in circular motion; there isn’t a real outward force there. The centrifugal force is a fictitious force used to analyze systems from the rotating perspective.

The other terms don’t describe this outward effect: centripetal force points toward the center, not away; threshold braking and friction relate to braking and contact forces but do not describe a force directed outward from the center in circular motion.