Angular Momentum of man holding a weight

[eprparadox]

Homework Statement

A man, holding a weight in each hand, stands at the center of a horizontal frictionless rotating turntable. The effect of the weights is to double the rotational inertia of the system. As he is rotating, the man opens his hands and drops the two weights. They fall outside the turntable. Then:

A. his angular velocity doubles
B. his angular velocity remains about the same
C. his angular velocity is halved
D. the direction of his angular momentum vector changes
E. his rotational kinetic energy increases

Homework Equations

L = I*w
Net Torque = dL/dt

The Attempt at a Solution

So the answer given is B. I kind of casually thought that the rotational inertia of the system decreases by a factor of 2 when the guy drops the weight so the angular velocity must double in order to keep it the same.

I guess don't really understand the physics of why angular momentum isn't conserved. If it's not conserved, then there should be a net torque acting correct? What is that torque?

Thanks a lot.

 

[collinsmark]

Angular momentum is conserved, as long as you keep the system large enough. One way to look at the problem is that when the man drops the weights, the weights are still part of the system; they're just no longer in his hands is all.