Arecord player turntable initially rotating at 3313 rev/min is braked to a stop at a constant rotational acceleration. the turntable has a rotational inertia of 0.031kg? m2 . when it is switched off, it slows down to 75% of its initial rotational speed in 4.0 s. a- how long does it take to come to rest? b- how much work has to be done on the turntable to bring it to rest?

15.99861 seconds

1865.58658 Joules

Explanation:

= Angular acceleration

= Angle of rotation

I = Moment of inertia of disc = 0.031 kgm²

t = Time taken

Initial angular speed

Final angular velocity

From the equation of rotational motion

Time taken by the turntable to slow down is 15.99861 seconds

Rotational energy is given by

The work has to be done on the turntable to bring it to rest is 1865.58658 Joules

it is the second option.