Physics
posted by RD .
A bullet of mass 3.2 g strikes a ballistic pendulum of mass 3.6 kg. The center of mass of the pendulum rises a vertical distance of 13 cm. Assuming that the bullet remains embedded in the pendulum, calculate the bullet's initial speed.

you can only use conservation of momentum on the collision
Momentumbullet=momentumbullet/pendulum
.0032*Vi=3.6032*Vf
Now you can consider energy after the collision
1/2 (3.6032)Vf^2=(3.6032)*9.8*.13
in the second equation, solve for Vf, then put it in the first equation, and solve for Vi.