Question

Length AB in figure shown is 5m. The body is released from A. Friction is sufficient for pure rolling to take place. The maximum time which anybody (which can roll) can take to reach bottom is

• A. 8 s
• B. 2 s
• C. 6 s
• D. 4 s

Answer 1

The correct option is B 2 s

Ring takes maximum time to reach bottom.
For ring$\frac{K^2}{R^2}=1$
$\therefore$ time taken t = $\sqrt{\frac{2l}{gsin\theta }(1+\frac{K^2}{R^2})}t=\sqrt{\frac{2\times 5}{10\times sin{30}^{\circ }(1+1)}}=2s$