4. A 5.00 g bullet moving with an initial speed of 400 m/s is fired into and passes through a 1.00 kg block (See figure). 400 m/s v 5.00 cm The block, initially at rest on a frictionless, horizontal surface is connected to a spring with force constant 900 N/m. If the block moves 5.00 cm to the right after impact, find: (a) the speed at which the bullet emerges from the block, [Ans: 100 m/s] (b) the mechanical energy converted into internal energy in the collision. [Ans: 374 J] http://server2.uploadit.org/files/ultimacarlos-untitled.JPG This question is almost similar to the one asked by someone here. The different is that a spring has been added to the block. I have lost the solution given by my lecturer. I tried to do it with conservation of energy but it failed. I forgot about how to solve this question. Can somebody please help me?