Formula of energy per unit weight

Click For Summary

Homework Help Overview

The discussion revolves around the application of Bernoulli's equation in a fluid dynamics context, specifically regarding a scenario with multiple exits from a streamline. Participants are examining the implications of having two exits and questioning the validity of the equation presented by the original poster.

Discussion Character

  • Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants are exploring whether Bernoulli's equation can be applied with two exits and questioning how to account for differing velocities at those exits. There is also a focus on the assumptions regarding pressure differences and whether they can be considered equal at both exits.

Discussion Status

The discussion is ongoing, with participants providing insights into the application of Bernoulli's equation and raising questions about the assumptions involved. Some guidance has been offered regarding the treatment of streamlines and pressure differences, but no consensus has been reached.

Contextual Notes

There is mention of an attachment indicating that the pressure is atmospheric at both exits, which may influence the discussion on pressure differences.

foo9008
Messages
676
Reaction score
4

Homework Statement


is the equation in the 3rd photo wrong ? since there are 2 exits , why shouldn't the eqaution become (P1 / y) + z + (8.33^2) / (2x9.81) = 0 + z +[ 2 (12^2) / (2x9.81) ] ?

Homework Equations

The Attempt at a Solution

 

Attachments

  • 112.PNG
    112.PNG
    61 KB · Views: 562
  • 113.PNG
    113.PNG
    13.1 KB · Views: 494
  • 114.PNG
    114.PNG
    10.8 KB · Views: 525
  • 115.PNG
    115.PNG
    34.6 KB · Views: 502
Physics news on Phys.org
Bernoulli's equation is in respect of one streamline. A given streamline can only have one entry and one exit.
 
haruspex said:
Bernoulli's equation is in respect of one streamline. A given streamline can only have one entry and one exit.
but there are 2 exit, just consider 1 exit and ignore the another 1 ? how if the velocity at the 2 exit are different ?
 
foo9008 said:
but there are 2 exit, just consider 1 exit and ignore the another 1 ? how if the velocity at the 2 exit are different ?
Bernoulli's equation is telling you they would be the same velocity. Consider two streamlines, one from the inlet to one outlet, and one to the other outlet. Same pressure difference, same height difference.
 
haruspex said:
Bernoulli's equation is telling you they would be the same velocity. Consider two streamlines, one from the inlet to one outlet, and one to the other outlet. Same pressure difference, same height difference.
how do you know that the difference in pressure are the same?
 
foo9008 said:
how do you know that the difference in pressure are the same?
The third attachment says the pressure is atmospheric at both exits.
 
  • Like
Likes   Reactions: foo9008

Similar threads

Understanding Energy per Unit Weight: Solving the Equation for Height
  • · Replies 5 ·
Replies
5
Views
3K
Free energy per unit volume of an ideal gas
  • · Replies 3 ·
Replies
3
Views
3K
Find mass per unit length of a string graphically
  • · Replies 5 ·
Replies
5
Views
4K
Unit conversion:lbm/lbf*h to (N/s)/N
  • · Replies 29 ·
Replies
29
Views
23K
Find the change in the Kinetic energy of an Ideal Gas
  • · Replies 39 ·
2
Replies
39
Views
5K
Force components for mass attached to two springs
  • · Replies 15 ·
Replies
15
Views
2K
Energy per unit length of a cylindrical shell of charge
  • · Replies 1 ·
Replies
1
Views
5K
How is Wave Intensity Calculated?
  • · Replies 6 ·
Replies
6
Views
2K
Stimulated emission per second per atom?
  • · Replies 2 ·
Replies
2
Views
2K
Finding z component of a unit vector
  • · Replies 2 ·
Replies
2
Views
3K