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A physics student says centripetal force is a distinct new force, separate from gravity, tension, friction, and normal force, that appears whenever something moves in a circle. What is wrong with this claim?
ACentripetal force is simply the name for whichever net force causes the circular motion, not a new force
BThe claim is correct, and centripetal force acts in addition to all other forces present
CCentripetal force only appears when friction is completely absent from the system
DCentripetal force is a fictitious force that appears only in a rotating reference frame
Answer & Solution
Correct answer: A. Centripetal force is simply the name for whichever net force causes the circular motion, not a new force
1. The definition given is that any net force causing uniform circular motion is called a centripetal force, which makes centripetal a label for a role, not a new type of force.
2. Gravity, tension, friction, and the normal force are the real forces at work, and whichever combination of them produces the net inward force is what gets called centripetal in that situation.
3. Saying centripetal force acts in addition to all other forces would double count the same net force, so that claim is incorrect.
4. Confusing centripetal force with a fictitious force reverses the idea entirely, since fictitious forces like the centrifugal force appear only in non-inertial frames, while centripetal force is a real net force analyzed from an inertial frame, and centripetal force is also not restricted to frictionless systems.
_Source: OpenStax College Physics (CC BY 4.0), Ch 6 "Uniform Circular Motion and Gravitation", section 6.3 Centripetal Force_
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