A person spinning on a platform has a rotational inertia of 4 kg m^2 and an angular velocity of 15 rad/s. The person extends their arms out, and their rotational inertia becomes 7.5 kg m^2. What is their new angular velocity?
I think the answer is 8 rad/s.
angular momentum is conserved:
intertia1*w1=inertia2*w2
4*15=7.5*w2
w2= go to the head of the class,you are right.