A grindstone has a moment of inertia of `10 kg m ^(2).` A constant torque is applied and the grindstone is found to have a speed of 200 rpm 20 sec, after starting from rest, what will be the torque ?

Options

A. `2.14 N s`
B. `6 Ns`
C. `4 Ns`
D. `3.33 pi Ns`

Explanation

To solve the problem, we need to find the torque applied to a grindstone given its moment of inertia and the final speed after a certain time. Here’s a step-by-step solution:

### Step 1: Convert the final speed from RPM to radians per second
The final speed of the grindstone is given as 200 revolutions per minute (RPM). We need to convert this to radians per second.

\[ \omega_f = 200 \, \text{RPM} \times \frac{2\pi \, \text{radians}}{1 \, \text{revolution}} \times \frac{1 \, \text{minute}}{60 \, \text{seconds}} \]
...