Sorry for the late reply here, but I figured it out today when i asked my physics teacher about it. She basically said the same thing you did collins. compare 2 blocks before and after collision. Thank you for the response though. Good to know I can come here for some help.
Thanks for letting...
Homework Statement
A block of mass m1 = 4.0 kg slides along a frictionless table with a velocity of +10 m/s. Directly in front of it, and moving with a velocity of +3.0 m/s, is a block of mass m2 = 9.0 kg. A massless spring with spring constant k = 1120 N/m is attached to the second block as in...