When you slam your fist on a wall, the reason it hurts so much is because the wall actually hits you with the same amount of force. Pretty crazy, huh? This is called an interaction, in which an action and a reaction force occur simultaneously.

Figure 1.7
The Cannon
Action- The cannon pushes the ball forward
Reaction- The ball pushes back on the cannon and causes it to recoil Nasa Quest

This happens wherever there is force involved, because for every action there is an equal and opposite reaction. When you jump up from a chair, the chair jumps downward, when you are pulling on a rope, the rope pulls you and ect.

Figure 1.4 Newton's copy of his book: Philosophiae Naturalis Principia Mathematica Wikipedia

For different mass the action and reaction forces change. The model for this change can be found in Newton’s Second Law, which states that acceleration is directly proportional to net force and inversely proportional to mass.

Figure 1.5 Nasa Table
Action- The CD’s push downwards on the table
Reaction- The table pushes up on the cd’s with an equal and opposite force.

Figure 1.6 Nasa Quest
Skateboard
Action- The foot pushes forwards on the skateboard
Reaction- The skateboard pushes backwards on the foot (But the person has a bigger Mass and the skateboard goes forward.)

This means that the power of the reaction force will be bigger with force and as the mass gets larger the reaction force becomes less. This means that if a mass were to be INSANELY large, there wouldn’t be much acceleration at all. For example, when you jump up, the Earth doesn’t move downward. This is because the Earth is so immensely big.