Question

An electric clock is hanging on the wall in the living room. The clock is unplugged, and the second hand comes to a halt over a brief period of time. During this period, what is the direction of the angular acceleration of the second hand?

Answer 1

Answer:

Explanation:

angular velocity of second is given by

$\omega_0=\frac{2\pi }{60}=\frac{\pi }{30}\ rad/s$

suppose clockwise motion is positive

It is given that second hand halt over a brief period of  time

using

$\omega =\omega _0+\alpha \cdot t$

$\omega =final\ angular\ velocity$

$\omega _0=initial\ angular\ velocity$

$\alpha =angular\ acceleration$

$t=time$

$\alpha =-\frac{\omega _0}{t}$

$\alpha =-\frac{\pi }{30t}\ rad/s^2$

so direction of angular acceleration is anti-clockwise(opposite to angular velocity) as it try to cease the motion