# Mass flow rate

1. Dec 6, 2008

### jimbo71

1. The problem statement, all variables and given/known data
see attachment

2. Relevant equations
Av=dV/dt
mass flow rate =roe*dV/dt

3. The attempt at a solution
the velocity at point c is 50m/s and the area of the opening is 0.04m^2. (50m/s)(0.04m^2)(1000kg/m^3)=2000Kg/s

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2. Dec 8, 2008

### Carid

Do you think these questions sometimes give you extra information in order for you to show that you know how to sort out the essential from the not useful?
At point B the pipe is wider than at C.
At B will the water be flowing faster, slower, or the same speed as a point C ?
Obviously the same amount of water must pass point B and point C.
So what can we say about the mass flow at B?

3. Dec 8, 2008

### stewartcs

Looks correct to me.

CS

4. Dec 8, 2008

### Carid

Stewart,
Yes he's right, but the question gives a lot of unnecessary detail and I was trying to see if he was misled by it.

5. Dec 8, 2008

### jimbo71

I was a little mislead by the simplicity of the problem. Since the 6th grade, I've known some problems give more information than needed.

6. Dec 9, 2008

### stewartcs

Typically when students give the correct answer it implies that they were not mislead by it!

CS