- #1
inkandgold
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Homework Statement
1) http://i.imgur.com/JbK13.gif
The figure below depicts the forces acting on a safe being pushed up an ramp by movers, Fa. The mass of the safe is 500 kg, the coefficient of static friction along the incline is μs = 0.41 and the coefficient of kinetic friction along the incline is μk = 0.34. The ramp forms an angle θ = 23° above the horizontal. The top of the wall is h = 1.0 m off the floor. What force needs to be applied to hold the safe in place?
2) http://i.imgur.com/ZTYbR.gif
A young boy with a broken leg is undergoing traction. Find the magnitude of the total force of the traction apparatus applied to the leg, assuming the weight of the leg is 75 N and the weight hanging from the traction apparatus is also 75 N, θ = 28°.
Homework Equations
None were given to me, but this is what I think they are:
1)Fs = μs * N
w = mg
2) horizontal component of the traction force = 2 * 75 * cos (28) = 132 N
The Attempt at a Solution
1) static friction cannot hold the safe in place without having it slide back down
x components: -mg sin(theta) + Ffr = 0 = mg sin(theta) + uN
y components: N - mg cos(theta) = 0
N = mg cos(theta)
therefore F = -mg sin(theta) + u(mg cos(theta))
I don't think this is right...
2) horizontal component of the traction force = 2 * 75 * cos (28) = 132 N
magnitude of the force exerted on the femur by the lower leg = 132 N
I really appreciate any help you can give me! Thank you so much!
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