Question

Stemming a chimney. A rock climber of mass 71 kg wants to make her way up the crack between two rocks as shown in the figure below. The coefficient of friction between her shoes and the rock surface is ìS = 0.90. What is smallest normal force that she can apply to both surfaces without slipping? Assume that the rock walls are vertical. Hint: Why is the normal force between the rock climber and the rock on the left equal to the normal force between her and the rock on the right?