[SOLVED] Elastic and Inelastic A 100 g block on a frictionless table is firmly attached to one end of a spring with k = 29 N/m. The other end of the spring is anchored to the wall. A 25 g ball is thrown horizontally toward the block with a speed of 5.9 m/s. Q1: If the collision is perfectly elastic, what is the maximum compression of the spring? Q2: in a perfectly inelastic collision, what is the maximum compression of the spring? For Q1 I tried to use: (1/2)mvi^2+(1/2)kx^2 = (1/2)mvf^2 + (1/2)kxf^2 and got change in x was .44 m, but it wasn't right... I did the same thing for the other part, and it was still wrong...please help. Oh, and I found the velocity of the ball after collision: Perfectly Elastic: vf=3.5m/s Perfectly Inelastic: vf=1.2m/s These were right.