Help with physics problem please?

In the figure below, a climber with a weight of 629.8 N is held by a belay rope connected to her climbing harness and belay device; the force of the rope on her has a line of action through her center of mass. The indicated angles are θ = 35.0° and = 27.5°. If her feet are on the verge of sliding on the vertical wall, what is the coefficient of static friction between her climbing shoes and the wall?





http://www.webassign.net/hrw/12-22.gif

Help with physics problem please?
draw an origin in the middle of the climber right where the cable wire touches her waist. make the y axis go straight up in the air vertically and make the x axis level with the horizonal


Positive y goes straight up in the air and positive x goes off to the right.


draw a free body diagram which is a dot with four arrows extending from the dot. One arrow labled F which stands for wall friction goes from the dot straight up along the +y axis.





arrow number 2 labled N which stands for wall normal goes from the dot straight to the right in the plus x direction





arrow 3 goes from the dot straight down towards the ground along the -y direction and its lable is W which stands for 'weight'





and then there is arrow number 4 the last arrow. it is at an angle. the previous 3 arrows were not at angles they were flush with an axis and needed no angle.





draw arrow 4 from the dot (which is the origin) upward and off towards the left so that it lies in quadrant four. this arrow is drawn parallel with the direction of the cable that holds the climber. all four arrows are straight lines, not curvy.





do the sum of the forces in the x axis and get an equation


N=Tsin27.5


do the sum in the y axis and get an equation


F+ Tcos(27.5)= (629.8)(98)


do the sum of torques about the origin and get an equation


Fsin(35)=Ncos(35)


do some algebra and solve for N and T and F. three equation and only 3 unknowns. when you get N go back to the sum in the y axis. instead of F+Tcos27.5=(629.8)(9.8)


say: uN + Tcos27.5=(629.8)(9.8) and solve for u.
Reply:Multipy the angles, then divide by the massxaccerleration



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