Question

A loop of radius 3 meter and weighs 150 kg. It rolls along a horizontal floor so that its centre of mass has a speed of 15 cm/sec. How much work has to be done to stop it –

• A. 3.375 J
• B. 7.375 J
• C. 5.375 J
• D. 9.375 J

Answer 1

Answer: (A)

3.375 J

Answer 2

Required work = Total K.E.

= $\frac{1}{2}$ mv² $\left( 1 + \frac{k^{2}}{R^{2}} \right)$

= $\frac{1}{2}Mv^{2}\left\lbrack 1 + \frac{k^{2}}{R^{2}} \right\rbrack$

= $\frac{1}{2}$× 150× (0.15)² (1+ 1) = 3.375 J