A cylindrical aluminum rod is attached to a wall by a hinge. A copper cable is attached to the rod at a point three-quarters of its length away from the wall and used to support the rod in a horizontal position. The diameter of the rod is 5.0 cm and its unstressed length is 4.0m; the cable makes an angle of 57 degrees with the horizontal. What is the tension in the cable?
First, look up the density of aluminum and compute the weight of the rod. Don't forget to multiply the mass by g to get the weight in newtons.
Then, set the moment about the hinge equal to zero, assuming the weight ot the rod acts at the middle. Solve for the unknown cable tension, also in newtons.