1. The problem statement, all variables and given/known data The following structure,A force F is applied to the right hinge.If the mass of the rods are equal ,and the length of the rod is equal,the intial angle is also equal to 90 degrees (a square),What is the intial acceleration of leftmost hinge ? 2. Relevant equations Coordinate systems ,differentiation 3. The attempt at a solution I am quite confused of where to start this problem.I think that stating the coordinates of the hinges,and then differentiating it to find the relation of acceleration.However, I keep getting that the acceleration is the same.Can someone please advise me some idea where to start ,and what principles are at work here.I have not got any idea (due to being inexperienced with problems with hinges like this).Thanks in Advance !