A disk of radius 0.4 cm and mass 0.7 kg is rotating at 5 rad/s. A second disk of radius 0.5 cm and mass 0.85 kg is rotating at 6 rad/s in the other direction. What is the combined angular velocity of the disks when the second disk is placed on top of the first?
Should I add up the momemta of the two disks separately and then combine them into one "disk" to find the speed? I have this equation set up.
1/2(0.7)(0.04)^2(5)+1/2(0.85)(0.05)^2(-6)=1/2((0.7)(0.04)^2 + (0.85)(0.05)^2)x
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If they are on the same rotatonal axis, addthem to get momentum. Then since momentum is conserved, set that equal to added moments of inertia*final angular velocity.
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