Newton’s third law

Definition

Newton’s third law states that for every action, there is an equal and opposite reaction. This principle explains the mutual forces of action and reaction between two interacting bodies.

5 Must Know Facts For Your Next Test

1. Newton’s third law applies to all interactions, including gravitational forces between celestial bodies.
2. The law helps explain why planets remain in orbit due to the balance of gravitational forces.
3. Rocket propulsion is a practical example of Newton's third law in action.
4. In astronomy, it is crucial for understanding tidal forces caused by gravitational interactions between Earth and the Moon.
5. The concept helps scientists predict the motion of objects in space by analyzing force pairs.

Review Questions

• How does Newton’s third law explain the motion of planets in their orbits?
• Give an example of Newton’s third law in astronomical phenomena.
• Why is Newton's third law important for understanding tidal forces?

Related terms

Gravitational Force:

The attractive force between two masses.

Orbital Motion:

The movement of an object around another object due to gravitational forces.

Action-Reaction Pair: Two interacting forces that are equal in magnitude but opposite in direction as described by Newton's third law.