Third Law Of Motion

Key Notes:

Newton’s Third Law of Motion

Definition:

Newton’s Third Law of Motion states that for every action, there is an equal and opposite reaction. This means that forces always come in pairs.

Action-Reaction Pairs:

Whenever one object exerts a force on a second object, the second object exerts a force of equal magnitude but in the opposite direction on the first object. These forces are called action and reaction forces.

Examples:

• Walking: When you walk, your foot pushes backward against the ground (action), and the ground pushes your foot forward with an equal and opposite force (reaction).
• Rocket Propulsion: In a rocket, the engines expel gas backward (action), and the reaction force propels the rocket forward.

Forces Are Equal in Magnitude:

The forces in action-reaction pairs are always equal in strength. However, they act on different objects, so they do not cancel each other out.

Forces Are Opposite in Direction:

The direction of the force exerted by the first object is opposite to the direction of the force exerted by the second object.

Impact on Motion:

The action and reaction forces do not cancel out because they act on different objects. Therefore, they affect the motion of each object involved.

Interaction with Objects:

This law explains how objects interact with each other. For example, when you push against a wall, the wall pushes back with an equal force.

Misconceptions:

It’s important to note that while the forces are equal and opposite, the resulting motion of the objects may not be the same due to differences in mass and other factors.

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