A solid disc and a solid sphere of the same radius roll down two identical inclines from the same height without slipping. Which reaches the bottom first?
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Question

A solid disc and a solid sphere of the same radius roll down two identical inclines from the same height without slipping. Which reaches the bottom first?

G1 Physics · Accepted Answer

Step 1: For rolling without slipping a=g sinθ/[1+I/(mR²)]. Step 2: The sphere has I/(mR²)=2/5, smaller than the disc value 1/2, so its acceleration is greater and it arrives first. Final answer: D — sphere.