# Homework Help: Fluid Dynamics

1. Oct 1, 2007

### momogiri

Question:
Water flows out of a 13.0mm-diameter sink faucet at 2.30m/s.
At what distance below the faucet has the water stream narrowed to 10 mm diameter?

What I've done is that...
I found A_1 (faucet) to be 0.0001327m^2
and A_2 (bottom) to be 0.000314159m^2

So I did the whole A_1*v_1 = A_2*v_2 thing
and found v_2 to be 0.915m/s

Then I plugged it in, into Bernoulli's equation
1/2*rho*v_1^2 + rho*g*y_1 = 1/2*rho*v_2^2 + rho*g*y_2 (cancelling out the P_1 and P_2 because they.. cancel..)

In which it is..
0.5*1000*2.3^2 + 1000*9.8*y_1 = 0.5*1000*0,9715^2 + 1000*9.8*y_2

2645 + 9800*y_1 = 471.906 + 9800*y_2
9800*(y_1 - y_2) = -2174.094

So.. h = 0.222m

Or so I thought... It's wrong, so what am I doing wrong? Is it my A_1 and A_2's, etc.???

2. Oct 1, 2007

### Astronuc

Staff Emeritus
Check this number. What diameter was used?

If the initial velocity is 2.3 m/s, how does one obtain 0.95 m/s for V2? The water accelerates with gravity.

3. Oct 1, 2007

### momogiri

:D Thanks for the reminder that water accelerates with gravity
That helped, and I got it :D