Multiple choice

A solid sphere, a disc and a ring of the same mass and radius are allowed to role down a frictionless inclined plane simultaneously from the same height. In this context, which one of the following statements is correct?

  1. The disc reaches down first

  2. The sphere reaches down first

  3. The ring reaches down first.

  4. All of them reach down simultaneously
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

For rolling without slipping, acceleration depends on moment of inertia: a = g*sin(θ) / (1 + I/mr²). Sphere has lowest I (2/5 MR²), giving highest acceleration ~0.714g*sin(θ). Disc has I = 1/2 MR² (acceleration ~0.667g*sin(θ)). Ring has highest I = MR² (acceleration ~0.5g*sin(θ)). Sphere reaches bottom first.

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