- #1

- 50

- 0

A 70kg climber is supported in the chimney by the friction forces exerted on his shoes and back. The static coefficients of frictions between his shoes and the wall, and between his back and the wall, are 0.80 and 0.60 respectively. What is the minimum force he must exert? Assume the walls are vertical and that friction forces are both at maximum...

Here is my answer.

For the climber to remain in contact with the wall.

Both Frictional Force(shoe) and Frictinal Force(back) = mg = 70*9.81

else he will fall...

Fn1= the force he must exert by his shoe

Fn2= the force he must exert by his back

therefore

Frictional Force(shoe)= 0.80 * Fn1

mg=0.80*Fn1

Fn1(shoe)=853.4N

Frictional Force(back) = 0.60* Fn2

mg=0.6*Fn2

Fn2(back)=1144.5N.

Therefore minimum normal force he must exert to satisfy both...= 1144.5N

Logical and correct?