A bullet of mass 10.5 g is fired into aninitially stationary block and comes to rest in the block. Theblock, of mass 0.80 kg, is subject to nohorizontal external forces during the collision with the bullet.After the collision, the block is observed to move at a speed of4.20 m/s.
a) Find the initial speed of the bullet.
b) How much kinetic energy is lost?