Which element is not a determinant of downhill force?

The correct choice indicates that the color of the object does not impact its downhill force. Downhill force is primarily influenced by factors such as the weight of the object, the angle of the slope, and the type of surface on which the object is resting.

The weight of the object affects the gravitational force acting on it, directly influencing how much force pulls the object downhill. The slope itself is crucial as it determines the angle of descent, which dictates the component of gravitational force acting parallel to the slope. Lastly, the surface type can contribute to the frictional forces that act against downhill movement. However, the color of the object does not play any role in these physical processes affecting motion and force, making it the element that is not a determinant of downhill force.