A disc of radius 2   m and mass 100   k g rolls on a horizontal floor. Its centre of mass has speed of 20   c m   s - 1 . How much work is needed to stop it?

Step-by-step solution

Energy of the cylinder = 1 2 m v 2 + 1 2 I ω 2 = 1 2 m v 2 + 1 2 m r 2 2 v 2 r 2 = 3 4   m v 2 = 3 4 × 100 × 20 × 10 - 2 2 = 3   J