A force F applied at point A is just large enough to tip over a block of mass M. The block will rotate about its bottom right corner. Find the magnitude of F. The picture for this is problem 13 at this link http://viewmorepics.myspace.com/index.cfm?fuseaction=viewImage&friendID=128765607&imageID=1460084048 The know that torque is force x radius, and the radius here is L. The correct answer is MgL/2H, so I suspect that gravity somehow plays a role in this. However, I don't know what to do. How is this horizontal force F be related to gravity? Where does the 2H come from?