This was a problem on my final exam that I couldn't figure out, it drove me insane. Someone please tell me it's impossible A spring has a 1kg block attached to it and a k of 30,000. A 2kg block moving at 30m/s over a frictionless surface hits and sticks to the 1kg block. What is the displacement of the spring? What frequency will it vibrate after impact? I figured out that the final velocity of both blocks will be 20m/s and the final mass will be 3kg. I could not figure out the final acceleration to use m*a=x*k I was not given the distance between the blocks or the time. Any ideas?