Final answer:
The Bernoulli effect explains how water pressure inside a nozzle can be less than atmospheric pressure due to an increase in water velocity, which results in pressure reduction allowing water to spray out.
Step-by-step explanation:
The question primarily revolves around the principles of fluid dynamics and the Bernoulli's principle. The water pressure inside a hose nozzle can indeed be less than atmospheric pressure due to the Bernoulli effect. This phenomenon can be explained in terms of the conservation of energy. If the velocity of water increases within the nozzle, the pressure decreases according to Bernoulli's equation. This pressure reduction allows the water to emerge against the opposing atmospheric pressure because the total mechanical energy (sum of the pressure energy, kinetic energy, and potential energy) remains constant in a fluid flow as long as there are no energy losses due to friction or turbulence.
For example, when water flows from a hose with a large diameter to one with a small diameter, the speed increases and consequently, the pressure decreases below atmospheric pressure. Despite this, water can spray out due to the velocity increase and the conversion of pressure energy into kinetic energy.