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 $

Show Answer

Answer:

Correct Answer: D

Solution:

$ \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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