Solving Friction Problem: Minimum Force Needed

[aquila457]

Homework Statement

a horizontal force F pushes against a block of mass m, which in turn pushes against a larger block of mass M. There is no friction between the larger block and the table, but there is friction between the two blocks (coefficient of static friction). What is the smallest force F that will hold m against M without letting m fall down?

Homework Equations

f=ma

The Attempt at a Solution

no idea

 

[PhanthomJay]

I gather that block m is elevated (not touching the table) as a force F is applied to that block which is in contact with block M on the table. Use your relevant equation to set up an equation in terms of F,the mass of both blocks (moving together), and a. Then look at block m alone and identify all forces acting on it. Use Newton' laws in both the x and y direction. In the y direction, there must be no acceleration. Show an attempt at a solution, please.

 

[aquila457]

thanks for the hint; i skipped ahead to some other problems, answer attempt will come soon