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A long thin rod of mass M and length L with two balls of mass M1 (same mass for both) attached is allowed to rotate about the horizontal axis shown. The bar is initially stationary. It is then hig with a piece of putty of mass M2 and speed v which sticks to one of the M1's.

a) Find the angular velocity of the system after the collision. The correct answer should be 6M2*v/ (6M1L + 3M2L + ML)

b) What angle will the sytem rotate through before coming to a stop? Assume that it must be between 180 and 270 degrees.

For part a,

Am I suppose to use the conservation of angular momentum.

IW = I_f*W_f

(1/12)ML^2 *w= (1/12)(M1+M2)*L^2*W_f

I am stuck though since I don't know how to account for v.

For part b,

The answer is 180 + arcsin(V^2/gL)

I don't know how to get to v^2/gL.