For a load supported by two slings, increasing the angle from the vertical causes the sling force to do what?

For a load supported by two slings, increasing the angle from the vertical causes the sling force to do what?

• A. Decreases
• B. Stays the same
• C. Varies with angle
• D. Increases

Answer: (D)

When two slings share a load, the vertical components of both sling tensions must add up to the weight. If each sling makes an angle θ with the vertical, the vertical component is T cos θ for each sling, so 2T cos θ = W. Therefore T = W/(2 cos θ). As the angle from the vertical increases, cos θ decreases, which makes T grow. So the sling force increases as the angle from the vertical increases (even though the horizontal components rise to spread the load, the tension in each sling goes up).

When two slings share a load, the vertical components of both sling tensions must add up to the weight. If each sling makes an angle θ with the vertical, the vertical component is T cos θ for each sling, so 2T cos θ = W. Therefore T = W/(2 cos θ). As the angle from the vertical increases, cos θ decreases, which makes T grow. So the sling force increases as the angle from the vertical increases (even though the horizontal components rise to spread the load, the tension in each sling goes up).