A disk and a sphere of same radius but different masses roll on two inclined pla

CuriousTab

Question
A disk and a sphere of same radius but different masses roll on two inclined planes of the same altitude and length. Which one of the two objects gets to the bottom of the plane first ?
Options
A. Depends on their masses
B. Sphere
C. Disk
D. Both reach at the same time

Correct Answer

Sphere

Explanation

Time does not depend on mass, else

$T ? \sqrt{(1 + \frac{k^{2}}{R^{2}})}$