1. (20 points) A 15-gram bullet, moving to the right at a speed of 250 m/s, hits a block of wood moving to the left on a friction-free surface at a speed of 1 m/s. The bullet emerges from the other side of the block moving at a speed of 100 m/s, and the block, while still moving to the left, has slowed to a speed of 0.5 m/s. a) What is the mass of the wood block? b) How much thermal energy was created as the bullet passed through the block