Question

The 72.5-kg climber in (Figure 1) is supported in the “chimney” by the friction forces exerted on his shoes and back. The static coefficients of friction between his shoes and the wall, and between his back and the wall, are 0.82 and 0.67, respectively. Assume the walls are vertical and that the static friction forces are both at their maximum. Ignore his grip on the rope.

Determine the minimum normal force he must exert.

Express your answer to two significant figures and include the appropriate units.

Answer 1

using equation

for force is F = N and F = m g

therefore

F₁ = ₁ and F₂ = ₂ N

F = F₁ + F₂

m g = ₁ N + ₂ N

N = mg / ( ₁ + ₂ )

N = 72.5 X 9.8 / ( 0.82 + 0.67 )

N = 476.845 N

the N = 476.845 N minimum normal force he must exert.