Normal force

Force exerted on an object by a body with which it is in contact, and vice versa

In mechanics, the normal force F N {\displaystyle F_{N}} is the component of a contact force that is perpendicular to the surface that an object contacts. In this instance, the word normal is used in the geometric sense and means perpendicular, as opposed to its common meaning of "ordinary" or "expected". A person standing still on a platform is acted upon by gravity, which would pull them down towards the Earth's core unless there were a countervailing force from the resistance of the platform's molecules, a force which is named the "normal force".

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