Question

Based on problem 38 from the end-of-chapter problems in chapter 12. What choice of pivot would most easily allow you to find the tension in the cable? (i.e., only using 1 equation to directly solve for the tension.) Briefly explain your reasoning.

a) Pivot at the center of mass
b) Pivot at one end of the cable
c) Pivot at the other end of the cable
d) Pivot at a point not on the cable

Answer 1

The best pivot to find tension with one equation is at the end of the cable attached to the load because the tension does not create any torque at that pivot.

Step-by-step explanation:

The most straightforward way to find the tension in the cable using just one equation is to choose a pivot point where the unknown forces do not exert any torque. In the case of a cable supporting a load, such as an elevator or a bridge, the best pivot choice is often at the end of the cable attached to the load. This is because the tension in the cable acts along a line that passes through the pivot, meaning it does not create any torque about that pivot. Consequently, the only torque at the pivot is due to the weight of the load, which is known, allowing for direct resolution of tension.