For every action, there is an equal and opposite reaction.
Here's what this means:
* Action Force: When one object exerts a force on another object (the action), this is called the action force.
* Reaction Force: The second object simultaneously exerts an equal and opposite force back on the first object. This is called the reaction force.
Examples:
* Pushing a wall: When you push a wall, you exert a force on it (action). The wall pushes back on you with an equal and opposite force (reaction). This is why you feel resistance when pushing a wall.
* Jumping: When you jump, your feet exert a force on the ground (action). The ground exerts an equal and opposite force back on your feet, propelling you upwards (reaction).
* Rocket propulsion: A rocket engine burns fuel and expels hot gas out of its nozzle (action). The gas exerts an equal and opposite force on the rocket, propelling it forward (reaction).
Important points:
* The action and reaction forces always act on *different* objects.
* The forces are equal in magnitude and opposite in direction.
* The forces always occur *simultaneously*.
Therefore, it's impossible for a force to occur alone. Every force has a corresponding and simultaneous reaction force.
