Action reaction force quick question

[Adam17]

Homework Statement

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

Homework Equations

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?

 

[TSny]

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.