A block of mass 5kg slides without friction at a speed of 8m/s on a horizontal table surface until it strikes and sticks to a mass of 4kg attached to a horzontal spring. The spring has a constant of k= 2000 n/m. The spring is in turn attached to a wall. How far will the spring be compressed before the masses come to rest. the answers are a.) .4 b.) .54 c.) .3 d.) .02 e.) .67 the correct answer is a My main question is am I tackling the problem right ? I know the equation for a spring is 1/2kx^2 = -w I know that work = delta k so i set 1/2mv^2=1/2kx^2 and i solved for x getting sqrt(mv^2/k) = x I assume that the 5kgs is a force acting upon the 4kg so i plug in in my values which are sqrt(5(8)^2/2000) = sqrt(320/2000) = .4 now although I arrived at the technical right answer, I'm not all sure I did the problem right. I very new to Potiental energy, springs, and what not Please help me if I'm wrong, and please correct me We can't learn without mistakes and constructive criticism Thank you !