A hoop of radius `2 m` weight `100 kg`.It rolls along a horizontal floor so that its centre of mass has a speed of `20 cm s^-1`. How much work has to be done to stop it ?

Explanation

Here, `R = 2m, M = 100 kg , v = 20 cm//s = 0.2 m//s`
Total energy of the hoop `= (1)/(2)M v^(2) + (1)/(2)I omega^(2) = (1)/(2)M v^(2) + (1)/(2)(MR^(2)) omega^(2) = (1)/(2)M v^(2) + (1)/(2)M v^(2) = M v^(2)`
Work required to stop the hoop = total energy of the hoop `W = M v^(2) = 100 (0.2)^(2) = 4` joule