Normal force

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. 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. 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. 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. In a simple case such as an object resting upon a table, the normal force on the object is equal but in opposite direction to the gravitational force applied on the object (or the weight of the object), that is, N = m g {displaystyle N=mg} , where m is mass, and g is the gravitational field strength (about 9.81 m/s2 on Earth). The normal force here represents the force applied by the table against the object that prevents it from sinking through the table and requires that the table is sturdy enough to deliver this normal force without breaking. However, it is easy to assume that the normal force and weight are action-reaction force pairs (a common mistake). In this case, the normal force and weight need to be equal in magnitude to explain why there is no upward acceleration of the object. For example, a ball that bounces upwards accelerates upwards because the normal force acting on the ball is larger in magnitude than the weight of the ball.