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?

Step-by-step solution

Acceleration of the object on rough inclined plane is a = g sin θ 1 + I mR 2 = g sin θ 1 + K 2 R 2 For sphere a 1 = 5 g sin θ 7                             ( K 2 R 2 = 2 5 ) For disc a 2 = 2 g sin θ 3                   ( K 2 R 2 = 1 2 ) a 1 > a 2 , so sphere will reach bottom first.