The angle between the sling leg and which line defines the sling angle?

• A. The horizontal
• B. The vertical
• C. L/H ratio
• D. Hypotenuse and opposite leg ratio

Answer: (A)

The sling angle is defined by the angle the sling leg makes with the horizontal line. This reference is used because it directly describes how far the leg is spread from the load horizontally, which controls how the weight is shared between the legs.

If each leg carries a tension T, the vertical component of that tension is T sin(phi) when phi is the angle with the horizontal. With two legs, the weight W is balanced by 2 T sin(phi), so T = W / (2 sin(phi)). As phi gets small (legs closer to horizontal), sin(phi) is small and the required tension grows large. As phi approaches 90 degrees (legs more vertical), sin(phi) approaches 1 and the tension tends toward W/2 per leg. This relationship shows why the angle relative to the horizontal is the quantity that defines the sling angle.