Angular momentum; turntable problem

[physicsstdnt]

Homework Statement

A 1.7 kg , 20cm--diameter turntable rotates at 140rpm on frictionless bearings. Two 480g blocks fall from above, hit the turntable simultaneously at opposite ends of a diameter, and stick.

What is the turntable's angular velocity, in rpm , just after this event?

Homework Equations

L = Iω
Where L is angular momentum.
L_before = L_after

The Attempt at a Solution

I'm not sure how to calculate the moment of inertia after the masses have landed on the turntable. for the turntable i used the equation I= .5MR^2 . Do I use the same equation for the two additional masses as well and add them to the moment of inertia of the turntable? or simply add the mass to the equation. (.5*(M_table + M_1 + M_2)*R^2)*ω or (I_table + I_m1 + I_m2)ω?

 

[gneill]

Treat them like point masses located at distance D/2 from the center of rotation.

 

[physicsstdnt]

Thank you sir, that did it