Physics

Problem

A grindstone rotates initially at

10\,\text{rad}\,\text{s}^{-1}

. It is accelerated at

3\,\text{rad}\,\text{s}^{-2}

for a time

\Delta t

and then decelerated at

-2\,\text{rad}\,\text{s}^{-2}

for

4\,\text{s}

, finally returning to its original angular speed of

10\,\text{rad}\,\text{s}^{-1}

. Determine the value of

\Delta t