NEET 2019 Physics question

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?

(1)3 JCorrect
(2)30 kJ
(3)2 J
(4)1 J

Answer: (1)

Solution

By the work-energy theorem, the work needed to stop the disc equals the magnitude of its total kinetic energy (translational plus rotational). For rolling without slipping, and :

K = + Iω^2 =

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Question ID VK-092383