Final answer:
The water emerges from the nozzle against the opposing atmospheric pressure due to the Bernoulli effect and conservation of energy.
Step-by-step explanation:
The water emerges from the nozzle against the opposing atmospheric pressure due to the Bernoulli effect, which is related to the conservation of energy.
According to the Bernoulli principle, as the speed of a fluid increases, its pressure decreases.
In the case of a hose nozzle, the water speeds up as it moves through the narrower opening of the nozzle, causing a decrease in pressure.
This decrease in pressure inside the nozzle allows the water to emerge against the opposing atmospheric pressure, as the higher pressure outside the nozzle pushes the water through the nozzle.