a 32 kg child stands at the edge of a circular platform that rotates at w=2rad/s about its center. Mass of platform=60kg, radius=2m.

Question

The child walks from the rim towards the center. Find the Angular speed when the child reaches a point 0.500 m from the center.

Answer 1

The law of conservation of angular momentum
L₁ = L₂
{(MR²/2) +(mR²)}ω₁ ={(MR²/2) +(mr²)}ω₂
ω₂=ω₁{(MR²/2) +(mR²)}/{(MR²/2) +(mr²)}=
=2{60•4/2 + 32•4}/(60•4/2+ 32•0.25}=
=3.875 rad/s

Answer 2

Thank you!