I have a problem in which a bullet is fired into a wooden block on a spring. At the time of the impact the block and the bullet inter into SHM. I am given amplitude, the mass of both the block and bullet, and the velocity of the bullet and am asked to give the spring constant. I was using Hooke's law where mg=-kx. I was calculating using the amplitude for x and the mass of the block (which is attached to the spring) for m. However, this did not seem to use all of the information given and I was wondering if I am missing something or if it is just a trick question. I then tried using m1v1=(m1+m2)v2 and (1/2)(m1+m2)v2^2=(1/2)kA^2, but when I plugged that value I found back into Hooke's law it did not give me any of my mass combinations. What am I supposed to do?