Question

The length of a second's hand in a watch is 1 cm. The change in its velocity in 15 sec is -

• A. Zero
• B. $\frac{\pi}{30\sqrt{2}}cm/s$
• C. $\frac{\pi}{30}cm/s$
• D. $\frac{\pi}{30} \times \sqrt{2}$ cm/s

Answer 1

Answer: (D)

$\frac{\pi}{30} \times \sqrt{2}$ cm/s

Answer 2

Change in velocity = $2v\sin\left( \frac{90}{2} \right) = \sqrt{2}V$

= $\sqrt{2}\left( \frac{\pi}{30} \right)\frac{cm}{s}$