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blue2004STi
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Homework Statement
Prof. Holland, in his younger days, (when he had a mass of 55kg) is in a lie-back climb along a fissure, with hands pulling on one side of the fissure and feet pressed against the opposite side. The fissure has width w = 0.25m, and the center of mass of the climber is a horizontal distance d = 0.43m from the fissure. The coefficient of static friction between hands and rock, μhands, is 0.42, and between boots and rock, μboots is 1.25.
What is the least horizontal pull by the hands and push by the feet that will keep him stable?
Homework Equations
Weight: 0 = (Ushands*Fa + Usboots*Fb) -539N
Fb=force by boots
Fa=force by hands
Torque: 0 = Fa*Distance from CM + Fb*Distance from CM
The Attempt at a Solution
So I tried setting up an equation for the forces made by the hands and feet which was the "Weight" equation above. Then I created the "Torque" equation. I knew since the climber(Professor Holland) was in static equilibrium that the both of them had to equal zero. I solved for both of the forces and keep coming up with A=786.6369N and B=166.89N and A+B(what they're looking for)=953.5269N.
I have to submit it online and it says that the answer is not correct. What am I doing wrong? I don't understand this problem!AHHHHH!
Thanks,
Matt
oh yeah forgot, thanks in advance for the help...it's much needed.
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