Fluid Flow and Projectile Motion

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Homework Help Overview

The problem involves fluid dynamics and projectile motion, specifically examining the flow of water through a pipe and its subsequent trajectory after exiting a nozzle. The scenario includes calculations related to the cross-sectional areas of the pipe and nozzle, velocities, and the distance traveled by water before hitting the ground.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning, Problem interpretation

Approaches and Questions Raised

  • Participants discuss the application of the continuity equation to find the velocity at the nozzle and question the accuracy of initial calculations. There are attempts to relate the vertical drop time to horizontal distance traveled, with some participants exploring kinematic equations.

Discussion Status

The discussion has progressed with participants providing insights on the relationship between the areas and velocities, as well as the time of flight for the projectile motion aspect. Some participants have offered guidance on simplifying the calculations, while others are still clarifying their understanding of the problem setup.

Contextual Notes

Participants are navigating through the implications of the problem's parameters, including the heights and speeds involved, and are considering the assumptions related to projectile motion in a fluid dynamics context.

dropgigawatt
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Homework Statement


Water travels through a pipe with a radius of 1 inch at a speed of 2 m/s. There is a nozzle at the end of the pipe with a radius of 1/4 inch. The pipe is horizontal and 2m above the ground. How far does the water travel in the air before hitting the ground?

r1 = 1 in.
r2 = 1/4 in.
V1 = 2 m/s
y = 2 m

Homework Equations



A1V1=A2V2
A = ∏r2
Δx = Vxt

The Attempt at a Solution



I found that A1 = 3.14 in.2 and A2 = .20 in.2
I plugged those in and found V2 = 31.4 m/s2.

Now I think I have to find t so I can work with Δx = Vxt but I'm not sure how to go about that or if that's even the direction I should be taking.

EDIT: I tried using kinematics, re-arranging V2 = V0^2 + 2aΔx. I plugged my values into -V0^2 / 2a = Δx and got -31.42 / 2(9.81) = 50.3 m
Would that be correct?
 
Last edited:
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dropgigawatt said:
I found that A1 = 3.14 in.2 and A2 = .20 in.2

You did not have to. All you need is the ratio ## \frac {A_1} {A_2} = \frac { \pi r_1^2 } {\pi r_2^2 } = \left( \frac {r_1} {r_2} \right)^2 = 16 ##, so the velocity at the nozzle is 32 m/s exactly.

I plugged those in and found V2 = 31.4 m/s2.

The result is inaccurate, and the dimension is wrong.

Now I think I have to find t so I can work with Δx = Vxt but I'm not sure how to go about that or if that's even the direction I should be taking.

The rest of the problem is simple projectile motion. You know the initial velocity and the initial height. Find where it strikes the ground.
 
The water is traveling both horizontally and vertically. They want you to find how far it travels horizontally when it hits the ground. How long does it take for an object dropped from a height of 2 m to reach the ground? How far does an object travel horizontally in that amount of time if its horizontal speed is 32 m/s?
 
I got it.
t = .64 s
displacement = 32(.64) = 20.4 m

Thanks guys!
 

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