<Table> <Tr> <Td> </Td> <Td> This article needs additional citations for verification . Please help improve this article by adding citations to reliable sources . Unsourced material may be challenged and removed . (November 2015) (Learn how and when to remove this template message) </Td> </Tr> </Table> <Tr> <Td> </Td> <Td> This article needs additional citations for verification . Please help improve this article by adding citations to reliable sources . Unsourced material may be challenged and removed . (November 2015) (Learn how and when to remove this template message) </Td> </Tr> <P> In mechanics, the normal force F n (\ displaystyle F_ (n) \) is that component of the contact force that is perpendicular to the surface that an object contacts . For example, the surface of a floor or table that prevents an object from falling . In this instance normal is used in the geometric sense and means perpendicular, as opposed the common language use of normal meaning common or expected . For example, a person standing still on flat ground is supported by a ground reaction force that consists of only a normal force . If the person stands on a slope and does not slide down it, then the total ground reaction force can be divided into two components: a normal force perpendicular to the ground and a frictional force parallel to the ground . In another common situation, if an object hits a surface with some speed, and the surface can withstand it, the normal force provides for a rapid deceleration, which will depend on the flexibility of the surface and the object . </P>

When does normal force equal force of gravity