Physics Circle home Student Login

Home›Chapters›Rotational Motion PYQs›Rolling Motion›Question 74

NEET 2016 (Phase 1) · Rolling Motion

Rolling Motion question from NEET 2016 (Phase 1)

Q74NEET 2016 · PHASE 1Medium

Rolling Motion

A disc and a sphere of same radius but different masses roll off on two inclined planes of the same altitude and length. Which one of the two objects gets to the bottom of the plane first?

Show answer and solution

Answer: (d)

  1. Rolling acceleration a=gsin⁡θ1+k2/R2a = \dfrac{g\sin\theta}{1 + k^2/R^2} does not depend on mass.
  2. Disc: k2/R2=12k^2/R^2 = \frac{1}{2}; sphere: k2/R2=25k^2/R^2 = \frac{2}{5} (smaller), so the sphere has larger aa.
  3. Same length, larger aa means less time: the sphere reaches first, answer (d).
Report a mistake

More questions on Rolling Motion