Question

A body rotating at 20rad//s is acted upon by a constant torque providing it a deceleration of 2rad//s^(2). At what time will the body have kinetic energy same as the initial value if thhe torque continues to act?

Answer 1

Given:

Initial velocity = 20 rad / s

Deceleration = 2 rad/s²

To Find: The time at which the torque continues to act

Solution:

The body will start accelerating in the opposite direction due to the torque effect.

Therefore,

initial Kinetic energy = velocity at any instant

Final velocity  =(-ω)= -20

Now,

ω' = ω - at

t = (2 × ω) / α

t = (2 × 20 )/2

t = 40/2

t = 20

Answer: The time when the torque continues to act is 20 seconds.