Q. A disc of radius 2m 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 ?
A) 3J
B) 30 kJ
C) 2 J
D) 1 J
Explanation
[Solution] KE of a rolling disc $= \frac{3}{4}mv^2 = \frac{3}{4} \times 100 \times 0.04 = 3$ J. Answer (1).
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.