A disc of radius 2 m and mass 100 kg rolls on a horizontal floor. Its centre of mass has speed of 20 cm/s. How much work is needed to stop it?
Answer & explanation
Correct answer: option 2
Work to be done = Change in kinetic energy
KEi = \(\frac{1}{2}mv^2 + \frac{1}{2} Iw^2\) = \(\frac{3}{4}mv^2\) = 3 J
KEf = zero
Work done : W = 3 J