Consider hitting a baseball with a bat. If we call the force on the bat against the ball the action force, identify the reaction force. Consider hitting a baseball with a bat. If we call the force on the bat against the ball the action force, identify the reaction force. The reaction force is zero because the force of the bat on the ball is equal and opposite to the force of the ball on the bat. The reaction force is the force by the ball on the bat. The reaction force is the force of the bat on the ball. The reaction force is the force due to compression inside the ball:_____________

Action and reaction force are an integral part of third law of Newton . They are equal and opposite force - couple which act on two opposite objects. That is why they can not make a body in equilibrium.

In the given case, a bat is hit by a ball , at the point of contact , two equal and opposite forces emerge simultaneously , one acting on the ball and the other acting on the bat. As per the problem , force on the bat is called action . So the other force , that is force acting on the ball is called reaction force.