Question

a volunteer firefighter holds the end of a firehose as a strong jet of water emerges. the hose exerts a large backward force on the firefighter. explain.
multiple choice
newtons third law of motion. the fast moving expelled water exerts a force of equal magnitude back on the hose and the firefighter who is holding the hose in place.
the weight of the water in the hose creates a backward force on the firefighter.
friction between the water and the hose lining creates a force pushing back on the firefighter.
atmospheric pressure acting on the hose nozzle pushes back on the water stream, creating an opposing force on the firefighter.

Explanation:

Newton's third law states that for every action, there is an equal and opposite reaction. When the hose expels water (action), the water exerts an equal - magnitude backward force on the hose (and thus the firefighter holding it), which matches the backward force on the firefighter. The weight of water (option B) relates to gravity, not the backward force from water expulsion. Friction (option C) is about resistance between surfaces, not the reaction force here. Atmospheric pressure (option D) doesn't explain the backward force from the water jet's expulsion.

Answer:

A. Newton's third law of motion. The fast moving expelled water exerts a force of equal magnitude back on the hose and the firefighter who is holding the hose in place.