Question

A disk 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?

• A. Depends on their masses
• B. Disk
• C. Sphere
• D. Both reach at the same time.

Answer 1

The correct option is C Sphere

We know that $a=\frac{gsin\theta }{1+\frac{k^2}{R^2}}$
In case of sphere, $\frac{k^2}{R^2}=\frac{2}{5}=0.4andincaseofdisk,\frac{k^2}{R^2}=\frac{1}{2}=0.5$
So $a_{sphere}>a_{disc}$
Hence sphere reaches first to the bottom of the plane.