1. The problem statement, all variables and given/known data A projectile of mass m = 50g traveling at v0 = 20m/s hits a block of mass M = 450g. The block rests on a frictionless horizontal surface and is attached to a spring of force constant k = 2000N/m. The projectile ricochets backward off the block with speed v’ = 0.6v0. The collision lasts for 4ms. (In the picture, the spring is attached to the block and the wall) a) What impulse is delivered to the block and what is the average force for the collision? b) Is the collision elastic? Justify your answer. c) What is the maximum compression of the spring? d) Suppose the surface has a “small” coefficient of friction μk = 0.1. Estimate the total distance the block traverses from the moment it is struck to when it comes finally to rest. Why is this only an estimate? For such an estimate to be accurate what is the criterion for “small” friction coefficient? 2. Relevant equations p=mv J=Δp fav= Δp/Δt KE=1/2mv2 Us=1/2kd2 (maybe?) vrel=-v'rel 3. The attempt at a solution a) momentum: mv0=mv'+Mv2' impulse on block: J=Δp=p2-p1 --> p2= mv0 - mv' = .4mv0 = .4 N⋅s fav= Δp/Δt = 100 N b) KE= 1/2 m v2 KE' +1/2mv'2+1/2Mv2'2 KE'/KE = [m(.6v0)+M(v0-.6v0)2] / mv02 =(.6)2 + (.450)(.4)2(.05) =>.40 --> 60% KE loss. non- elastic and this is where I am second guessing myself.