How does sling angle affect the load on each leg in a two-leg lift?

How does sling angle affect the load on each leg in a two-leg lift?

• A. The load on each leg stays constant regardless of the angle.
• B. As the sling angle from vertical increases, the load on each leg increases.
• C. Near vertical, each leg carries nearly all the load.
• D. The angle does not affect the load distribution.

Answer: (B)

The key idea is that the amount of force each leg must carry depends on how far the legs are spread from vertical. When a load W is suspended by two legs that form equal angles θ with the vertical, the vertical components of the tensions in the two legs must add up to W. Each leg therefore has tension T, with 2 T cos θ = W, so T = W / (2 cos θ). As θ increases (the sling angle from vertical grows), cos θ decreases, which makes T larger. So each leg has to pull harder to keep the load up. When the legs are nearly vertical (small θ), cos θ is close to 1, and T is about W/2, meaning each leg carries roughly half the load. As the angle becomes wider, the tension in each leg rises, even though the total weight stays the same. This is why keeping sling angles modest is important for safety. Other options aren’t accurate: the load on each leg isn’t constant with angle, near-vertical lifting does not put most of the weight on one leg, and the angle does affect how the load is shared between the legs.

The key idea is that the amount of force each leg must carry depends on how far the legs are spread from vertical. When a load W is suspended by two legs that form equal angles θ with the vertical, the vertical components of the tensions in the two legs must add up to W. Each leg therefore has tension T, with 2 T cos θ = W, so T = W / (2 cos θ). As θ increases (the sling angle from vertical grows), cos θ decreases, which makes T larger. So each leg has to pull harder to keep the load up.

When the legs are nearly vertical (small θ), cos θ is close to 1, and T is about W/2, meaning each leg carries roughly half the load. As the angle becomes wider, the tension in each leg rises, even though the total weight stays the same. This is why keeping sling angles modest is important for safety.

Other options aren’t accurate: the load on each leg isn’t constant with angle, near-vertical lifting does not put most of the weight on one leg, and the angle does affect how the load is shared between the legs.