Which simple machine is primarily used for lifting or lowering loads?

The incline plane is primarily used for lifting or lowering loads because it allows a load to be moved vertically by employing a sloped surface. This design reduces the amount of force needed to lift an object compared to lifting it straight up. By applying force parallel to the slope, the load can be raised or lowered gradually, making it easier and more efficient to handle heavier weights.

This principle is especially useful in various applications, such as loading ramps, where heavy items can be wheeled up or down the slope instead of being lifted directly. The incline plane utilizes the mechanical advantage offered by its slope, providing a practical solution for tasks involving heavy lifting or the movement of loads upward or downward. Other simple machines like wedges, levers, and screws serve different functions and do not primarily focus on vertical movement in the same manner as the incline plane.