I have a problem where a 20 gram bullet is fired at 1200m/s throguh a 45 gram block and emerges at 900m/s. I am asked to find the time that the bullet took to pass through the block which leads into a follow-on question about finding total force applied. I do not even know how to approach this problem to find an answer. Please help! I believe that I need to use a kinetics equation but the subsequent parts of the question ask for the speed of the block after the collision, using conservation of momentum, which I have already solved. Itried the conservation of momentum delta rho=force x delta time= mass times delta veloity but keep coming up with missing conversion factors.