A bullet (5 grams) is fired horizontally into a block of wood (2 kg) suspended from the ceiling by strings of length 1.5 meters.
The bullet embeds itself in the block of wood. Immediately after the bullet embeds in the wood, the wood and bullet are moving 1.5 m/s.
The event can be divided into two parts:
1) In a very little time the bullet embeds itself into the wood. Gravity can be ignored in this part.
2) The wood block with the bullet, which is suspended by the strings, swings upward by height h.
Immediately after the bullet embeds itself in the wood, which is the best approximation of the kinetic energy of the block and bullet?