# Action reaction force quick question

In summary, the firewoman opening the fire hose creates an action force of the water pushing on the air, which results in a reaction force of the air pushing back on the water. This can also be seen in the hose exerting a force on the water, with a reaction force of the water exerting a force on the hose. In a vacuum, there would be no force of the water on air, but the other action-reaction pairs would still occur.

## Homework Statement

A firewoman opens the fire hose, and water sprays forward. What is the action force and reaction force?

none

## The Attempt at a Solution

I was thinking that the action force would be water pushing on air and reaction air pushing on water? But how would this be possible in space where there is a vacuum?

I think the question is rather ambiguous. The firewoman exerts a force on the hose to hold it at rest. There will be a corresponding reaction force. Can you describe this reaction force?

Also, the hose will exert a force on the water. What is the reaction force to this?

As you stated, the water will exert a force on the air as it moves through the air. And you correctly stated that the reaction force would be the air exerting a force on the water.

[By the way, when dealing with action-reaction pairs, it doesn't matter which of the two forces you call the "action" force and which the "reaction" force.]

If the hose and firewoman are in a vacuum, then of course there would be no force of the water on any air. But you would still have the other action-reaction pairs mentioned above.

## 1. What is an action-reaction force?

An action-reaction force, also known as Newton's third law of motion, states that for every action, there is an equal and opposite reaction. This means that when an object exerts a force on another object, the second object will exert an equal force in the opposite direction.

## 2. How does an action-reaction force affect motion?

An action-reaction force does not affect the motion of an object. This is because the forces are acting on different objects and therefore do not cancel each other out. The motion of an object is determined by the net force acting on it.

## 3. Can an object have an action-reaction force with itself?

No, an object cannot have an action-reaction force with itself. This is because for an action-reaction force to occur, there must be two objects involved. An object cannot exert a force on itself.

## 4. Are action-reaction forces always equal in magnitude?

Yes, action-reaction forces are always equal in magnitude but opposite in direction. This means that the forces are the same size, but act in opposite directions.

## 5. How do action-reaction forces play a role in everyday life?

Action-reaction forces play a role in many everyday activities such as walking, riding a bike, or even sitting in a chair. The force of your foot pushing down on the ground causes an equal and opposite reaction force from the ground, propelling you forward. Similarly, the force of your hands pushing on the handlebars of a bike causes an equal and opposite reaction force from the bike, allowing you to move forward.

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