A person on a rotating stool with arms stretched out rotates at an angular speed of 5.00 rad/s. On bringing in his arms, the angular speed increases to 7.50 rad/s. By what factor does the moment of inertia change?

Answer 1

conservation of angular momentum
L₁=L₂
I₁ω₁=I₂ω₂
I₁/I₂=ω₂/ω₁

Answer 2

.60