Question

A grindstone has a moment of inertia of 6 kg m2. A constant torque is applied and the grindstone is found to have a speed of 150 rpm, 10 seconds after starting from rest. The torque is

• A. $3 \pi \mathrm { Nm }$
• B.
• C. $\frac { \pi } { 3 } \mathrm { Nm }$
• D.

Answer 1

Answer: (A)

$3 \pi \mathrm { Nm }$

Answer 2

Here, I = 6 kg t = 10 s

$\omega _ { 0 } = 0$

$\alpha = \frac { \omega - \omega _ { 0 } } { \mathrm { t } } = \frac { 5 \pi - 0 } { 10 } = \frac { \pi } { 2 } \mathrm { rad } \mathrm { s } ^ { - 2 }$

$\therefore$ Torque,