Question

In a traction setup for a broken bone, with pulleys and rope available, how might we be able to increase the force along the femur using the same weight? (See Figure 4.30.) (Note that the femur is the shin bone shown in this image.

Short answer

The force can be increased or decreased using the same weight using pulleys and ropes.

Step-by-step solution

The tension in the rope is equal to the weight of the leg.Step 1: Concept of Normal Force

Whatever supports a load, it must supply an upward force equal to the weight of the load. This upward force is called the normal force.

Determine the tension in the rope

Referring to figure 4.30, the traction setup shown helps in increasing the force across the broken bone using ropes and pulleys. By changing the angle${}^{\mathrm{\theta }}$ shown in the figure, the magnitude of the force can be increased because as the value of ${}^{\mathrm{\theta }}$ is increased ${}^{0°\mathrm{to}90°}$, the value of ${}^{\mathrm{sin\theta }}$also increases.

Hence, the force can be increased or decreased using the same weight.