I Have A Really Hard Time

A bullet of mass mi, is fired at a speed vo, at a pendulum bob of mass m2.
The pendulum is not hung from a string but rather a stiff rod, of length amp;
that is able to pivot freely. Assume the mass of the rod is negligible. After the
collision the bullet’s speed has decreased to half its original speed.
(a) Determine the minimum value of vo, in terms of the quantities
given in the problem and the acceleration of gravity g, that will
allow the pendulum bob to barely swing through a complete circle.
(b) Use Proportionality sense-making to analyze your answer to part (a).
If the ratio of mi/ ma increases, do you expect your answer in part
(@) to increase or decrease? Explain.Science