question_answer 19)

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

Answer:

Here R = 2 m, M = 100 kg,   Work required to stop the hoop = Total K.E. of the hoop = Rotational K.E. + Translational K.E.   .