Problem 13. A bullet of mass m and speed v is fired horizontally and passes completely through a pendulum bob of mass M. The bullet emerges with a speed of

. The pendulum bob is suspended by a stiff rod of length d and negligible mass. What is the minimum value of v such that the pendulum bob will swing through a complete vertical circle? Hint: think carefully about the impact of there being a stiff rod in this problem and not a string.