# Homework Help: Airfoil pressure

1. Jul 22, 2007

### hallo

Hi,

velocity of air=0, an airfoil or wing with is moving forwards with a velocity of 40m/s at an altitude of 1100m. At a certain point close to the wing (which is a point on top of the wing) ,the air speed relative to the wing is 50m/s.Find the pressure at that point.

Somebody pls help me.....

I trz to use the formula of 1/2*(density)*(velocity)^2 + pressure + (density)*g*z which is bernoulli"s equation and is wrong.....

thanx

2. Jul 23, 2007

### chaoseverlasting

1/2d*40*40 +p1=1/2d*50*50 +p2. I think this should be it. Is this what you did?

3. Jul 23, 2007

### hallo

yes,but how to get p1 and p2 ??

4. Jul 23, 2007

### Astronuc

Staff Emeritus
5. Jul 23, 2007

### hallo

static air pressure equals to 1.23 * 9.81 * 1100m . Am I rite?? but the answer is wrong if I use this value...

6. Jul 23, 2007

### Astronuc

Staff Emeritus
It would appear that one is using $\rho{gh}$, and therefore one is finding the pressure at the bottom of a column of air of 1100 m height. Of course, one can subtract that value from 1 atm and obtain an reasonable approximation of the air pressure at 1100m above sea level.