Hi, I was giving a problem by my teacher that will most likely be on the exam. A block, m1, is ontop of another block, m2 and there is a constant friction, mu, between the two blocks. Between block m2 and the ground there is no friction. What is the largest force, P, that can be put on m2 and have m1 stay in its same position. I have F=m1a and F=m2a, F = (mu)N1 = (mu)m1g. It seems really easy but for some reason I am having trouble with it. Thanks Edit: My exam is in an hour so I was typing fast without thinking.