Question

A horizontal steel bar of uniform mass density and mass 5kg is supported by two vertical steel cables atteached to the ends of the bar. When a 75kg mass hangs from the center of the bar the tension in each cable is?

Answer 1

400 N

Step-by-step explanation:

Since the steel bar is uniform, its center of mass must be at its geometric center as well, which is at the same spot as the 75kg mass hanging. So the total mass is 75 + 5 = 80 kg.

Suppose g = 10m/s2, we can then calculate the weight of the system:

W = Fg = 80 * 10 = 800 N

As the weight is at the center with 2 ropes supporting on 2 ends, weight should be evenly distributed on each rope. So each rope is subjected to a tension force of

T = 800 / 2 = 400 N