weight is the force of a body on a surface or on a rope. So why isn't it always perpendiculair to the surface, for example in a slope. When a slope is so steep that it's vertical, there is no weight. But when the slope is a little diagonal you talk about a weight (which faces down(to the center of the earth)) and a perpendiculair component of weight. The perpendiculair weight is equal to the normal force. But if the definition of weight is the force on a surface to remain it's height, why isn't weight (in contrast to gravityforce) always perpendiculair? this question can also be stated in a different way: is the normal force always eqeal to the weight?