[Schweitzer]

I'm taking the Physics Subject test on Nov. 3rd as well.

For the first problem I just use conservation of energy. Initial Potential energy = Final Kinetic Energy
M*g*(height of center of mass) = .5 * M * V^2
Height of center of mass is obviously L/2
V=[(g*L/2)*2]^.5

For the second I just assume pennies are point masses and sum:
I=mr^2
Since all m's and r's are equal (in magnitude) then
I=6mr^2