Kinematics Question 112
Question: The length of second hand watch is 1 cm. The change in velocity of it’s tip in 15 seconds is [MP PMT 1987]
Options:
A) Zero
B) $ \frac{\pi }{30\sqrt{2}}cm/\sec $
C) $ \frac{\pi }{30}cm/\sec $
D) $ \frac{\pi \sqrt{2}}{30}cm/\sec $
Correct Answer: D $ \Delta v=2v\sin ( \frac{90{}^\circ }{2} )=2v\sin 45{}^\circ $ $ =2v\times \frac{1}{\sqrt{2}}=\sqrt{2}v $ $ =\sqrt{2}\times r\omega =\sqrt{2}\times 1\times \frac{2\pi }{60}=\frac{\sqrt{2}\pi }{\grave{\ }30}\ cm/s $
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