Newtons third law of motion

vocabulary

Newton's third law When one body exerts a force on a second, the second body exerts and equal and opposite force on the first.
Force A push or pull of any object, that tends to accelerate.  
Reaction force the force that is equal in strength and opposite in direction to the action force, which acts simultaneously on whatever is exerting the action force.
Action force one of the pair of forces described in Newton’s 3rd law.
Mass The amount of matter in an object: a measure of an object’s inertia.  
Weight Measure of gravitational force acting on an object