I saw this idea on another forum and I though it'd be fun if it was employed here, a marathon works as follows: 1. One person posts a problem. 2. Then another person solves it and then posts another problem. 3. Another person comes and solves the second problem and then posts another problem. I suggest we keep the problems limited to classical topics. But, this is isn't a rule of course. I'll start: Problem 1: The sign shown below (See attached photo) consists of two uniform legs attached by a frictionless hinge. The coefficient of friction between the ground and the legs is μ. What is the maximum value of θ such that the sign will not collapse?