1. The problem statement, all variables and given/known data 2 bricks of mass m are located near the edge of a smooth horizontal surface, they are connected by an ideal weightless ,unstretched spring with a length of l0 and spring constant k. The brick which is closer to the edge is connected to another brick of the same mass by an ideal unstretchable rope going through a pulley. The lowest brick is held so that the rope above it hangs vertically. The lowest brick is released What's the minimal time τ after which the elongation of the spring ΔL will be maximal. Find ΔL. 2. Relevant equations 3. The attempt at a solution Here's the solution until the point where I'm stuck. Sorry for the Russian text, it does not contain crucial information, please ignore it a2-a1 is the acceleration of one end of the spring from the frame of reference of another end. Then these equations are given (y is vertical coordinate) I understand why w2 is 3k/2m but why is the amplitude(A0) mg/3k? Can someone please explain? I only need an explanation for A0 The next equations are At the beginning the system is in equilibrium and then x(0)=0, that leads to B being equal to 0 and and A0+A=0 because the spring isn't stretched at the beginning. Thanks.