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**1. Homework Statement**

A flat construction of two circular rings that have a common center and are held together by three rods of negligible mass. The construction, which is initially at rest, can rotate around the common center (like a merry-go-round) through which another rod of negligible mass extends. Mass 1 is 0.12 kg, its inside and outside radii are 0.016 m and 0.045 m, respectively. Mass 2 is 0.24 kg, its inside and outside radii are 0.090 m and 0.140 m, respectively. A tangential force of magnitude 13.0 N is applied to the outer edge of the outer ring for 0.300 s. What is the change in the angular speed of the construction during that time interval?

**2. Homework Equations**

I believe the following is the correct moment of inertia formula for this problem:

I = (1/2)M(R1^2 + R2^2)

**3. The Attempt at a Solution**

What I have done so far is calculate each ring's moment of inertia.

Ring 1:

I1 = (1/2)M(R1^2 + R2^2)

I1 = (1/2)(0.12 kg)((0.016 m)^2 + (0.045 m)^2)

I1 = 1.3686e-4 (kg*m^2)

Ring 2:

I2 = (1/2)M(R1^2 + R2^2)

I2 = (1/2)(0.24 kg)((0.090 m)^2 + (0.140 m)^2)

I2 = .003324 (kg*m^2)

This is as far as I have gotten and I am not even sure if the work I have done thus far is relevant. I am not sure what to do with the tangential force provided by the problem. I know F = ma, but I am not sure where that, or if it even does, fit in. Please help, this one has been stumping me for a while. Thanks for your time.