In uniform circular motion, what provides the centripetal force?

In uniform circular motion, what provides the centripetal force?

• A. Gravity provides the centripetal force.
• B. The net inward force toward the center provides the centripetal force.
• C. The tangential force provides the centripetal force.
• D. The centrifugal force provides the centripetal force.

Answer: (B)

In uniform circular motion, the velocity is changing direction even though its speed stays the same, so there is an acceleration directed toward the center of the circle. That inward acceleration has to come from an inward net force, by Newton’s second law. The force that points toward the center and has a magnitude equal to m v^2 / r is what we call the centripetal force. Importantly, there isn’t a separate, special force named “centripetal”; it’s just the sum of real forces that points inward and produces the inward acceleration. Gravity can provide this inward pull in some situations (like planets orbiting the sun or a car going around a banked curve under gravity and normal force), but it is not the universal source of centripetal force. The tangential force would change the speed, not keep it constant in a circular path, so it doesn’t supply the required inward acceleration for uniform circular motion. The centrifugal force is a fictitious force that appears in a rotating (non-inertial) frame and does not act as the real inward force in the inertial frame. So the correct understanding is that the inward net real force provides the centripetal acceleration.

In uniform circular motion, the velocity is changing direction even though its speed stays the same, so there is an acceleration directed toward the center of the circle. That inward acceleration has to come from an inward net force, by Newton’s second law. The force that points toward the center and has a magnitude equal to m v^2 / r is what we call the centripetal force. Importantly, there isn’t a separate, special force named “centripetal”; it’s just the sum of real forces that points inward and produces the inward acceleration.

Gravity can provide this inward pull in some situations (like planets orbiting the sun or a car going around a banked curve under gravity and normal force), but it is not the universal source of centripetal force. The tangential force would change the speed, not keep it constant in a circular path, so it doesn’t supply the required inward acceleration for uniform circular motion. The centrifugal force is a fictitious force that appears in a rotating (non-inertial) frame and does not act as the real inward force in the inertial frame. So the correct understanding is that the inward net real force provides the centripetal acceleration.