Newton's Third Law Calculator

All physics tools

Explore the Principle of Action and Reaction.

Action Parameters

Action Force (F₁)

Mass of Object 1 (m₁)

Mass of Object 2 (m₂)

Reaction Results

Enter action force to see reaction

About this calculator

Quick Reference

F₁Force exerted by Object 1 on Object 2

F₂Force exerted by Object 2 on Object 1

a₁F₁ / m₁

a₂F₂ / m₂

Overview

Newton's Third Law states that for every action, there is an equal and opposite reaction. This means that forces always exist in pairs. If Object A exerts a force on Object B, Object B exerts a force of equal magnitude and opposite direction on Object A.

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Pro Tips

The forces are equal in magnitude but opposite in direction.
The forces act on DIFFERENT objects.
Even if the masses are very different, the force exerted is exactly the same.
Acceleration will differ if the masses are different (a = F/m).

Fun Facts

"Rockets work because of Newton's Third Law: they push gas down, and the gas pushes the rocket up."
"When you walk, you push the Earth backward, and the Earth pushes you forward."
"The 'recoil' of a gun is a classic example of this law in action."

Formula: F₁ = -F₂