A firefighter at the scene of a fire is holding a heavy hose out of which water is gushing. To keep her balance, she often has to lean. Which way does she lean, forward or backward, and why?

1 Answer

This question may be related to Newton's third law of motion.


According to Newton's third law, in every interaction, for every action there is a reaction that is of equal magnitude and opposite direction.

In this case, as the hose water gushes forward, a reaction force is applied by the water on the hose, meaning that there is a backward force applied on the hose. As the firefighter is holding the hose, the backward force is also applied to her. In order to keep her balance, i.e. to be in translational equilibrium, the vector sum of the forces has to be zero, i.e. all forces cancel out. Hence, she has to lean forward for there to be a forward force to maintain her balance.