Backward Reaction Force on a Fire Hose, Myth or Reality?

Excerpt

The reader may have noticed a backward force when using a hose, if not, searching the internet for “fire hose car lift” or “flyboard” provides videos of a car or a man suspended in the air by the use of fire hoses. The widely accepted explanation for the backward force produced by a firehose on the firefighters uses Newton’s third law in a way that is conceptually wrong. To provide empirical evidence that a backwards reaction force does not exist on a straight hose, we performed a simple experiment that shows that the force produced by water emerging from the nozzle of a straight hose produces a force that stretches the hose. A backwards force appears only when water flows inside a curved hose because water hits the walls of the hose producing a force that is transmitted to the firefighters. The correct application of Newton’s laws to understand the forces on a firehose makes it possible to devise new solutions to efficiently fight a fire without having to diminish the water flow to lower the reaction forces in the nozzle. Under this new perspective, it is possible to diminish the forces produced by the nozzle on the firefighters by maintaining the end of the hose as straight as possible and locking the curved hose segments to stationary objects. …