1. The problem statement, all variables and given/known data Two large crates with masses 640kg and 490kg are connected by a spring (k = 8.1kN/m) and are being pushed across a level frictionless force applied horizontally to the more massive crate. The spring compresses 5.1cm from equilibrium length? What is the applied force? 2. Relevant equations F = -kX 3. The attempt at a solution I am unsure as to what to do right here. As it is a frictionless surface, won't any force move the masses? F = -kx = -(8100N/m)(0.051m)= - 413.1N. This is what I figure, but I am pretty sure it is wrong, I don't know how the masses affect this. That is how much force is required to compress the spring by 0.051m, but how much is required to move the boxes as well?