When lifting a load with two slings, at what angle to the horizontal is the load on each sling equal to the load's weight?

When lifting a load with two slings, at what angle to the horizontal is the load on each sling equal to the load's weight?

• A. 45 degrees
• B. 30 degrees
• C. 15 degrees
• D. 60 degrees

Answer: (B)

When two slings share a load, the vertical components of their tensions must add up to the load weight. If each sling makes an angle θ with the horizontal, and the tension in each sling is T, then the vertical component of each tension is T sin θ, and the total vertical support is 2 T sin θ = W. To have the load in each sling equal to the load’s weight, set the sling tension equal to W (T = W). Plugging in gives W = 2 W sin θ, so sin θ = 1/2, which yields θ = 30 degrees. So at 30 degrees to the horizontal, each sling carries a tension equal to the load’s weight. If the angle is larger, each sling’s tension is less; if smaller, each sling’s tension is greater.

When two slings share a load, the vertical components of their tensions must add up to the load weight. If each sling makes an angle θ with the horizontal, and the tension in each sling is T, then the vertical component of each tension is T sin θ, and the total vertical support is 2 T sin θ = W.

To have the load in each sling equal to the load’s weight, set the sling tension equal to W (T = W). Plugging in gives W = 2 W sin θ, so sin θ = 1/2, which yields θ = 30 degrees.

So at 30 degrees to the horizontal, each sling carries a tension equal to the load’s weight. If the angle is larger, each sling’s tension is less; if smaller, each sling’s tension is greater.