A ballistic pendulum consists of a 1.25-kg block of wood that is hanging from the ceiling in such a way that when a bullet enters it, the block’s change in height can be recorded as it swings. A bullet having a mass of 6.25-grams and unknown velocity strikes the block and becomes imbedded in it. The impulse imparted to the block causes it to swing in such a way that its height increases by 7.15 cm.

Question

1 What was the change in potential energy of the block/bullet combo after the collision?

2What was the speed of the block/bullet combo immediately after the collision (and before it began
to swing)?

3What was the speed of the bullet before entering the block of wood?

I know this is long but please anyone help me and I will pray for him for the rest of my very short life:)

Answer 1

change in PE=(M+m)g*height

1/2 (M+m)v^2=above PE change solve for v

m*Vbefore=(M+m)vabove
solve for Vbefore.