# Homework Help: Pressure (continued)

1. Feb 25, 2008

### JWHooper

1. The problem statement, all variables and given/known data
Calculate the absolute and gauge pressure at the bottom of a 2.5 m deep container, if it is full of gasoline (density = 690 kg/m^3). Assume the container is open at the sea level.

2. Relevant equations
P = P_0 + Dhg

3. The attempt at a solution
P = (690 kg/m^3)(2.5m)(9.8 m/s^2) = (1.69 x 10^4 Pa)(1 kPa/10^3Pa) = 1.69 x 10 kPa (gauge pressure)
(1.69 x 10^4 Pa) + (1.01 x 10^5 Pa) = 1.18 x 10^5 Pa (absolute pressure)

My questions (important!):
1. Did I do these right?
2. Also, what is P_0 in the equation P = P_0 + Dhg?
3. gauge pressure + 14.7 lb/in^2 = absolute pressure ----> true or false? If not, please explain.

Thanks,

J.

2. Feb 25, 2008

### Mentz114

P = P_0 + D.h.g

absolute pressure = atm. pressure + gauge pressure.

Interesting to speculate whether, if it was all underwater, the gauge pressure would be negative ?

3. Feb 25, 2008

### JWHooper

So, P is the absolute pressure, P_0 is the atm. pressure, and Dhg is the gauge pressure?

4. Feb 25, 2008

### Mentz114

5. Feb 25, 2008

### JWHooper

Okay. Now, disregarding P_0, did I do the solution correctly?