. A platform with boat weighs 10,000 N. Four cables are attached to the platform as shown; the edges of the platform are always a horizontal distance of 2 m from the pulleys. As the platform rises smoothly and evenly, the length L of the cables decreases and the angle θ gets smaller.
The pulleys are 5 m above the waterline. The cables have a diameter of 5 mm, and are made of a material with mechanical properties E = 200 GPa, σy = 382 MPa, and ν = 0.27. Assume a factor of safety of 1.5.
a) How high will the boat/platform be when the tension in the cables exceeds the allowable stress?
b) At that height, determine the length L of a cable from the platform to its pulley. How much will that cable length L deform due to the tension at that height?
c) What will be the final diameter of the cable?
2 answers