# Homework Help: Formula of energy per unit weight

1. Mar 18, 2016

### foo9008

1. The problem statement, all variables and given/known data
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) ] ?

2. Relevant equations

3. The attempt at a solution

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2. Mar 18, 2016

### haruspex

Bernoulli's equation is in respect of one streamline. A given streamline can only have one entry and one exit.

3. Mar 18, 2016

### foo9008

but there are 2 exit, just consider 1 exit and ignore the another 1 ? how if the velocity at the 2 exit are different ?

4. Mar 18, 2016

### haruspex

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.

5. Mar 18, 2016

### foo9008

how do you know that the difference in pressure are the same?

6. Mar 18, 2016

### haruspex

The third attachment says the pressure is atmospheric at both exits.