(adsbygoogle = window.adsbygoogle || []).push({}); 1. A fire hose exerts a force on the person holding it. This is because the water accelerates as it goes from the hose through the nozzle. How much force is required to hold a 7.5 cm diameter hose delivering 470 L/min through a 0.80 cm diameter nozzle?

2. Relevant equations

I think we need to use the continuity eqn: A1V1 = A2V2 = Q

and the Bernoulli eqn: P + (rho)gh + 1/2 (rho)v^2 = constant

3. The attempt at a solution

Using the continuity equation, I found the velocities in the nozzle and in the hose

V1 (in nozzle) = 38.97 m/s

V2 (in hose) = 1.77 m/s

Then I used the bernoulli equation to solve for the pressure in the hose.

P1 = P2 + 1/2 (rho)[(v2)^2-(v1)^2]

with P2 = 1.0*10^5 Pa

P1 = 857830.4646 Pa

Then I said P = F/A

F = PA = 857830.4646 Pa(Area of hose)

F = 3789.8 N

But this is the wrong answer - I wonder if my logic itself is faulty?

**Physics Forums | Science Articles, Homework Help, Discussion**

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Homework Help: Water Hose Force Problem

**Physics Forums | Science Articles, Homework Help, Discussion**