This simulation demonstrates the conditions under which a ball and box will slide or roll/tumble. Us the drop down menu to select a box or ball. Adjust the angle of the incline and the coefficient of static friction using the slider. In cases where sliding occurs, the simulation assumes . The friction and normal force are shown originating from a single point. In reality, these forces act everywhere there is contact, and the magnitude of those forces varies with position. The vectors drawn represent the location that an equivalent average force could be applied to cause the same behavior.