what maximum force can be exerted by the string on the top block without causing the top block to slip

Question

1. A block of mass m = 5.00 kg rides on top of a second block of mass M = 10.0 kg. A person attaches a string to the top block and pulls the system horizontally across a horizontal, frictionless surface, as shown in the Figure in attachment. If the coefficient of static friction between the two blocks is 0.350, what maximum force can be exerted by the string on the top block without causing the top block to slip?

Answer 1

Maximum force = coefficient of static friction x normal force on upper block

= 0.350 x 5 x 9.81 N

The mass of the lower block is irrelevant