If the sling angle from vertical increases, the forces in the individual sling legs do what?

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

Answer: (C)

As sling legs spread away from vertical, the load must be held up by the vertical components of tension in both legs. If each leg makes an angle theta with the vertical, the vertical component of each leg’s tension is T cos(theta). With two legs, 2 T cos(theta) equals the load W, so T = W / (2 cos(theta)). When theta increases, cos(theta) decreases, so the required tension T in each leg increases. In short, increasing the sling angle from vertical makes the force in each leg grow. If the angle gets very large, the tension becomes very large. The force does vary with angle, but the trend is that it increases as the angle from vertical grows.