Rotational Motion Question 55
Question: A wheel having moment of inertia $ 2kg-m^{2} $ about its vertical axis, rotates at the rate of 60 rpm about this axis. The torque which can stop the wheel’s rotation in one minute would be:
[AIPMT (S) 2004]
Options:
A) $ \frac{2\pi }{15}N-m $
B) $ \frac{\pi }{12}N-m $
C) $ \frac{\pi }{15}N-m $
D) $ \frac{\pi }{18}N-m $
Show Answer
Answer:
Correct Answer: C
Solution:
-
Given: $ I=2kg-m^{2},{\omega_0}=\frac{60}{60}\times 2\pi rad/s, $ $ \omega =0,t=60s $
The torque required to stop the wheels rotation is $ \tau =I\alpha =I( \frac{{\omega_0}-\omega }{t} ) $
$ \therefore $ $ \tau =\frac{2\times 2\pi \times 60}{60\times 60}=\frac{\pi }{15}N-m $
