# Homework Help: Physics Buoyancy Problem

1. Dec 12, 2012

### asheik234

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

A house has a roof with an area of 220 m2. Wind blows over the top with a speed of 10 m/s. The density of air is 1.29 kg/m2. The air inside the house is stagnant. Point A is just inside the roof, and point B is outside the roof at the same height.

(a) What is the difference in pressure (PA - PB) between points A and B?

(b) What force is applied to the roof by the inside air?

2. Relevant equations
This is where I'm stuck at

3. The attempt at a solution
I don't know what equations to apply here, they all involve mass, but that's not a given.

2. Dec 12, 2012

### Staff: Mentor

Have you studied the Venturi effect? Look it up.

3. Dec 12, 2012

### asheik234

Yes, i've studied it, but how does that apply here?

4. Dec 12, 2012

### Staff: Mentor

Um, air flowing faster over roof than under roof... air pressure difference... area of roof...

5. Dec 12, 2012

### asheik234

Oh yes, I realized that, but I don't know where to go from there, what equations should I use.

6. Dec 12, 2012

### Staff: Mentor

What equation pertains to the venturi effect? Look up venturi effect.

7. Dec 13, 2012

### rude man

Check Bernoulli.