Hi, this is my first post and am trying to answer the following scenario out of a general curiousity. Scenario: Suppose a firemen is standing in front of a doorway with a firehose. He then points the nozzle of the firehose at the doorway a foot behind the door frame He then turns on the water to a level where he is barely able to keep from being pushed back by the water exiting the nozzle. The door is then closed and the water is hitting it at a foot distance from the nozzle. Question: Will the fireman experience more force pushing him back with the door closed than with the door opened? If yes, what are the laws to explain this? Thanks!