Use the worked example above to help you solve this problem. A block of mass m = 5.50 kg rides on top of a second block of mass M = 15.0 kg. A person attaches a string to the bottom block and pulls the system horizontally across a frictionless surface as in figure (a). Friction between the two blocks keeps the 5.50 kg block from slipping off. If the coefficient of static friction is 0.330, answer the following. Use the values from PRACTICE IT to help you work this exercise. Suppose instead that the string is attached to the top block as shown in figure (b). Find the maximum force that can be exerted by the string on the block without causing the top block to slip. I just need help with the last part "Find the maximum force that can be exerted by the string on the block without causing the top block to slip." Thanks for your help