Question

A disk has rotational inertia 1.22 x 10${}^{-3}$ kg-m${}^2$ and is attached to an electric drill whose motor delivers a torque of 15.8 N-m.

The angular speed v of the disk 33 ms after the motor is turned on is:

• A. $2.83\times {10}^4$rad/s
• B. $3.32\times {10}^6$ rad/s
• C. $3.48\times {10}^4$ rad/s
• D. $8.54\times {10}^4$rad/s

Answer 1

The correct option is C $3.48\times {10}^4$ rad/s

$\tau =I\alpha$
$\alpha =1.162\times {10}^{6}rad/se{c}^2$
$\omega =\alpha t$
$\omega =3.48\times {10}^{4}rad/sec$