Tonight I've got so many hard problems... A 3.0 kg mass slides across a frictionless surface and collides against a spring bumper with a velocity of 3.0 m/s as shown in the diagram. Determine the maximum amount of the spring compresses if it spring constant is 335 N/m. For this one I don't know whether I should use E_kin = E_spring then solve from there or E_kin(i) + E_spring(i) = E_kin(f) + E_spring(f), but as for the former I got: 1/2 mv^2 = 1/2 k (delta) l^2 mv^2 = k(delta) l^2 (3)(3)^2 = (335) (l^2) x = .081 m Is that right? Thanks a lot for your help so far, everyone! I really appreciate your time and kindness.