Final answer:
Friction loss in a fire stream is the pressure used to overcome the resistance within a fire hose. It's influenced by factors like hose material and water properties, and is crucial for effective firefighting. The equation of continuity and Bernoulli's principle explain how water can emerge forcefully from a nozzle despite friction loss.
Step-by-step explanation:
In reference to a fire stream, friction loss is defined as B. that part of the pressure that is used to overcome friction in the hose. Friction loss refers to the loss of pressure as water moves through a fire hose, which is the energy required to overcome the resistance to flow within the hose due to the hose's material, length, and diameter, as well as the viscosity and velocity of the water. This loss of pressure can impact the effectiveness of fire fighting efforts, as it affects the distance and intensity with which the water can be projected from the nozzle.
According to the equation of continuity and Bernoulli's principle, when water flows through a hose and out a nozzle, its velocity increases as it passes through the narrower opening, which corresponds with a reduction of pressure in that region. Even though the pressure in the nozzle is less than atmospheric pressure, the kinetic energy of the water allows it to emerge from the nozzle with sufficient force to overcome the opposing atmospheric pressure. This kinetic energy that the water possesses is due to the work done on the fluid as it is forced through the hose and nozzle. Therefore, despite friction loss, the water can exert a considerable force when it strikes a surface.