Question

How do inertia and centripetal force combine to keep an object moving in circular motion?

Centripetal force acts toward the center of the circle to overcome inertia, which acts away from the center.
Inertia acts toward the center of the circle to overcome centripetal force, which acts away from the center.
Centripetal force acts toward the center of the circle, and inertia keeps the object moving forward.
Inertia acts toward the center of the circle, and centripetal force keeps the object moving forward.

Answer 1

Correct answer: 3.

Explanation: Centripetal force is a real force (or net radial component of forces) that points toward the center and continuously changes the direction of the object’s velocity. Inertia (Newton’s first law) is not a force but the object’s tendency to keep moving in a straight line (tangentially). The inward centripetal force constantly redirects that tangential motion, producing the inward (centripetal) acceleration v^2/r and keeping the object in circular motion. (If you’re in the rotating frame you may talk about a fictitious “centrifugal” force that appears to act outward.)