A woman with a mass of 45.0 kg is standing on the rim of a large disk that is rotating at an angular velocity of 0.490 rev/s about an axis through its center. The disk has a mass of 120 kg and a radius of 4.50 m. Calculate the magnitude of the total angular momentum of the woman-plus-disk system. (Assume that you can treat the woman as a point.) Ok, well I first converted rev/s into rad/s. 0.490 rev/s * 2(pi) = 3.079 rad/s Next I determined that the moment of inertia for a disk is (1/2)mr^2 Next I used the equation for angular momentum: L = I(omega) = [(1/2)mr^2]omega = [(1/2)(120 kg + 45 kg)(4.50m)^2]*3.079 rad/s = 5143.8 kg m^2/s This one seemed really straightforward to me, but the program I use for physics says the answer isn't right. Anyone know what I did wrong?