# Homework Help: Find force (N) of atmosphere on area

1. May 4, 2010

### Calhoun295

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

Your eardrum has an area of about 53 mm2. Sounds become painful to your ear when the pressure variations that are involved in sound reach 200 Pa above and below normal air pressure. At this level, called the threshold of pain, how much force is exerted on your eardrum?

2. Relevant equations

Pressure=$$\frac{Force}{Area}$$

3. The attempt at a solution

F=PA
F= 101000N/m^2 (.053m^2)
F= 5353 N

I've tried normal atmosphere above and below 200Pa. The answer isn't correct according to wileyplus. I'm obviously doing it wrong, so whats wrong with my equation?

2. May 4, 2010

### tiny-tim

Hi Calhoun295!

(try using the X2 tag just above the Reply box )
No, you'll have Patm on one side of your eardrum, and Patm ± 200 on the other side … net pressure = ±200.

3. May 4, 2010

### RoyalCat

Also note that $$53 mm^2= 53 \cdot ((10^{-3} m)^2) = 53\cdot 10^{-6} m^2$$