Compare static and dynamic loads in crane lifting.

• A. Static loads are constant weight.
• B. Dynamic loads include acceleration and sway.
• C. Static loads create higher peak forces than dynamic loads.
• D. Static loads are constant weight; dynamic loads include acceleration, deceleration, and sway that create higher peak forces.

Answer: (D)

In crane lifting, static loads are the constant weight the crane must hold, acting as a steady force with no movement. Dynamic loads arise from motion and changes in motion: when you start lifting, accelerate, or stop, inertia resists those changes, which increases the tension in the lifting rope and the forces on the hook and crane structure. Sway of the load adds further dynamic effects, introducing sideways forces as the payload moves back and forth. Because of these dynamic factors, the peak forces experienced during lifting can exceed the simple static weight. This is why the statement that static loads are constant weight; dynamic loads include acceleration, deceleration, and sway that create higher peak forces is the most accurate description.