Verified answer

compare rotational energy before and after. They should be equal

so:

I_1 * omega_1^2 / 2 = I_2 * omega_2 ^2 / 2

I_2/I_1 = (omega_1/omega_2)^2 =

(2/5)^2=0.16

Angular momentum will be conserved, so her (moment of inertia) times her (angular velocity squared) before will have to be equal to those measurements after. That means 4 times (2.0^2) her initial moment of inertia will have to equal 25 (5.0^2) times her final moment of inertia. This means her moment of inertia decreased TO a measure of 4/25 (0.16) as much as the initial moment, or decreased BY a factor of 25/4 (6.25). Good luck!

5/2 = 2.5

3 revs. Geme' 10 points!

2.5

3.3679

9.26