Force results from interactions!, some forces result from 'contact' interactions(normal, frictional,
tensional, and applied forces are examples of contact forces) and other forces (gravitational,
electrical, and magnetic forces) According to Newton, whenever an object A and B interact with
each other, they exert forces upon each other. When you sit in your chair, your body exerts a down-
wards force on the chair and the chair exerts an upward force on your body. There are two forces
resulting from this interaction-a force on the chair and a force on the body. These two forces are called
'Action' and 'reaction' forces and are the subject of Newton's third law of motion.
Formally stated, Newton's third law is:
For every action, there is an equal and opposite reaction.
This statement means that in every interaction, there is a pair of forces acting on the two interacting
objects. The size of the forces on the first object 'equals' the size of the force on the second object
"equals" the size of the force on the second object. The direction of the force object is "opposite" to
the direction of the force on the second object.
Forces always come in pairs-equal and opposite action-reaction force pairs.
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