Final answer:
The minimum fluid speed in a fire hose with a 9.00-cm diameter carrying 80.0 L of water per second is 12,579 m/s. If saltwater replaced the freshwater, the fluid speed would be different due to the change in density.
Step-by-step explanation:
To determine the minimum fluid speed in a fire hose, we need to use the equation Q = Av, where Q is the flow rate, A is the cross-sectional area of the hose, and v is the fluid speed. The flow rate in this case is 80.0 L/s, and the diameter of the hose is 9.00 cm. By converting the flow rate to cubic meters per second and calculating the cross-sectional area of the hose, we can find the fluid speed. Moreover, the flow rate would be different if saltwater replaced freshwater due to the change in density.
Using A = πr^2, we find that the radius of the hose is 0.045 m. Therefore, A = π(0.045)^2 = 0.00636 m^2.
Now, let's calculate the fluid speed:
Q = Av
80.0 L/s = 0.00636 m^2 * v
v = 80.0 L/s / 0.00636 m^2
v = 12,579 m/s
So, the fluid speed in the fire hose is 12,579 m/s.
If salt water replaced fresh water in the fire hose, the answers would be different because the density of saltwater is higher than freshwater. The increase in density would result in a higher fluid speed in the hose.