How High Can Pumped Water Reach in a Building Fire?

Click For Summary

Homework Help Overview

The problem involves determining the maximum height that water can reach when pumped from a hose during a building fire. The scenario includes specific parameters such as the flow rate of water, the area of the hose exit, and the angle of projection.

Discussion Character

  • Exploratory, Conceptual clarification, Problem interpretation

Approaches and Questions Raised

  • Participants discuss the application of fluid dynamics principles, including the equation of continuity and Bernoulli’s equation. There is a consideration of whether to treat the water as a solid projectile or to apply fluid dynamics concepts. Some participants question the necessity of additional information once the exit velocity is known.

Discussion Status

The discussion is progressing with participants clarifying their understanding of the problem. There is a shift in perspective from viewing the situation as a pressure problem to recognizing it as a projectile motion problem. Guidance has been provided regarding the treatment of water as a projectile.

Contextual Notes

Participants are navigating assumptions about fluid behavior and the applicability of different physics principles in this context. The problem is framed within a real-world emergency scenario, which may impose constraints on the assumptions made.

monicaalves
Messages
2
Reaction score
0

Homework Statement



There is a fire in a building, so the fireman connects a hose to a hydrant that pumps 2 litres of water per second. The exit of the hose has and area of 15cm^2.
Which is the maximum floor of the building that the water can reach considering that it exits the hose at an height of 1,5m from the ground with an angle of 75 degrees?


Homework Equations



The pressure in a fluid at depth h in the fluid: p = Po + dgh
Equation of continuity for fluids: A1.v1 = A2.v2
Bernoulli’s equation: p1 + 1/2dv1^2 + dgh = constant

The Attempt at a Solution



Assuming that the area of the exit of the hose is the same of the area where the water exist the hydrant, I can assume using the equation of continuity that the velocity that the water is being pumped will the the same at the exit of the hose and I can find that value.
In this case, should I imagine the water like a solid object being launched from the ground, or is there any other equation to use when we are dealing with fluids?
 
Physics news on Phys.org
This is really a "projectile problem." Treat each little parcel of water exiting the hose as a separate (non-interacting) mass. You know the initial velocity of the projectile and the angle that it is launched. Determine the maximum height that the projectile reaches.
 
If you know the velocity of water exiting the hose, do you really need to know anything else to find how high it can go?
 
Thank you for you explanation Chestermiller, now I understand. I was looking at this as a pressure problem, but I just need to see water as a projectile and it's solved :)
 

Similar threads

  • · Replies 4 ·
Replies
4
Views
4K
  • · Replies 12 ·
Replies
12
Views
2K
  • · Replies 8 ·
Replies
8
Views
3K
  • · Replies 3 ·
Replies
3
Views
4K
  • · Replies 5 ·
Replies
5
Views
4K
  • · Replies 8 ·
Replies
8
Views
3K
Replies
7
Views
3K
  • · Replies 13 ·
Replies
13
Views
20K
  • · Replies 2 ·
Replies
2
Views
5K
Replies
2
Views
3K