A student stands on a frictionless turntable

PHYSICS · Subjective · A Level · Physics · Engineering physics · Engineering physics

Problem

70\,\text{kg}

student stands on a frictionless turntable. The student plus turntable have a combined moment of inertia of

6.0\,\text{kg}\,\text{m}^2

. The student holds two

2.0\,\text{kg}

dumbbells, each

1.0\,\text{m}

from the axis, and the system rotates at

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

. The student then pulls the dumbbells to

0.30\,\text{m}

from the axis. Determine the angular speed after the dumbbells are pulled inward.