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**1. The problem statement, all variables and given/known data**

diagram: http://goo.gl/uPl0

__Part A__

A bullet of mass 0.0175 kg and speed v

_{b}passes completely through a pendulum bob of mass 1.3 kg. The bullet emerges with a speed 0.5v

_{b}. The pendulum bob is suspended by a stiff rod of length 1.1 m and negligible mass. The acceleration of gravity is 9.8 m/s

^{2}. What is the critical value v, such that when v

_{b}> v , the pendulum bob will barely swing through a complete vertical circle?

__Part B__

Suppose that the pendulum bob is suspended from a light flexible cord instead of a stiff rod.

Now what is the minimum value of v such that the pendulum bob will swing through a

complete vertical circle?

**2. The attempt at a solution**

I was able to get part A by using conservation of momentum and conservation of energy and ended up with 975.61 m/s for v.

However, I am stuck on part B and do not know how to proceed. I know it has something to do with the tension of the cord, but am not exactly how to factor that in.

Any help would be much appreciated. Thanks!