Two blocks each of length L are piled near the end of the table. What is the maximum distance between the edge of the table and the edge of the outer block before the system topples? I understand that if the center of mass of the system must be to the left of the edge of the table for the system to be balanced. Is this correct? However, I don't understand how to do the calculations. Let x1 be the center of the lower block, and x2 be the center of the upper block. The average location of the center of these two blocks is then (x1+x2)/2. This is a distance (L/2-(x1+x2)/2) away from the center of the lower block. I can calculate the distances between the centers of the blocks and the edge of the table, but I don't understand what is the condition for the system to be balanced. Is it that the center of mass of the entire system be to the left of the edge of the table? The answer is: 3/4*L.