Statics
Quiz 1
A motorized wench is used to lift a 1kN crate using an overhanging
pulley as shown. The slope of the cable from the wench to the
pulley is 3:4. The cable is continuous.
1) Draw a FBD of the pulley.
2) Find the force vector F acting on the pulley.
3) Find the magnitude and unit vector of the force F.
2) Summation of forces in the x and y or vector addition yields
T+F+W=0
(-4/5)w i + (-3/5)w j + F + (-w) j = 0 i + 0 j
With w = 1 kN = 1000 N
F = 800N i + 1600 N j
3) || F || = sqrt(800^2 + 1600^2) N = 1789 N
4
3
A