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A rider on a rapidly spinning merry-go-round feels pushed outward and must hold on tightly. What name is given to this outward push, and what causes the rider to actually need to hold on?
AA real force that pulls the rider outward
BThe centripetal force, needed so it does not vanish
CA fictitious force, real force from holding on turns them
DFriction alone explains it, nothing else needed
Answer & Solution
Correct answer: C. A fictitious force, real force from holding on turns them
1. In the rotating frame of the merry-go-round, the rider feels a fictitious force called the centrifugal force, which seems to throw them off the edge.
2. In Earth's frame there is no such outward force at all, since the rider's own inertia would carry them off in a straight line if nothing held them on.
3. Holding on supplies the real centripetal force needed to keep the rider moving in a circle rather than flying off tangent to the path.
4. Calling the outward push a real force, confusing it with centripetal force, or attributing everything to friction alone all misidentify which force is real and which is fictitious in this situation.
_Source: OpenStax College Physics (CC BY 4.0), Ch 6 "Uniform Circular Motion and Gravitation", section 6.4 Fictitious Forces and Non-inertial Frames: The Coriolis Force_
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