Action (physics)

Action in physics is when things happen because of how they interact with each other. It's like when you push a toy car and it moves forward - the action of you pushing the car makes it go.

In order for an action to happen, there has to be something causing it. This is called a force. Forces are things that push or pull objects in different directions. When two things interact with each other, there are always forces involved.

For example, when you pick up a pencil, your fingers are exerting a force on the pencil. But the pencil is also exerting a force on your fingers. This is called an equal and opposite force. The force you exert on the pencil is equal in magnitude but opposite in direction to the force the pencil exerts on your fingers.

The total action of all the forces involved in a system is called the action-reaction pair. This means that for every action, there is an equal and opposite reaction. So if you push a toy car forward, the toy car is also pushing back on you with an equal force in the opposite direction.

In summary, action in physics is when things happen because of how they interact with each other, and this interaction is caused by forces. And for every action, there is an equal and opposite reaction, forming the action-reaction pair.