# Pascals Law

• Apr 23rd 2008, 10:11 AM
AngelzUnit
Pascals Law
Hello, I got a test coming up, but I don't think I'm getting this correct

If Pressure = Force/Area...

1) Force = 400 lbs Area = 1&1/2 sq in Pressure = ?

Pressure would equal 26.67 PSI?

2) Pressure = 800 PSI Area = 1/2 sq in Force = ?

Force would equal 1600 or 400 lbs?

3) Force = 800 lbs Pressure = 400 PSI Area = ?

Area would equal 2 sq in or 320,000 sq in?

I know this must be very simple but it's the first time I'm doing it.

Thanks for the help
• Apr 23rd 2008, 10:57 AM
Aryth
Quote:

Originally Posted by AngelzUnit
Hello, I got a test coming up, but I don't think I'm getting this correct

If Pressure = Force/Area...

1) Force = 400 lbs Area = 1&1/2 sq in Pressure = ?

Pressure would equal 26.67 PSI?

2) Pressure = 800 PSI Area = 1/2 sq in Force = ?

Force would equal 1600 or 400 lbs?

3) Force = 800 lbs Pressure = 400 PSI Area = ?

Area would equal 2 sq in or 320,000 sq in?

I know this must be very simple but it's the first time I'm doing it.

Thanks for the help

1. We have:

$\text{Force} = 400 \text{ lbs.}$

$\text{Area} = 1\frac{1}{2} in^2 = 1.5 in^2$

So, our formula is:

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

Plug in what we know:

$Pressure = \frac{400}{1.5}$

$Pressure = 266.67 \frac{lbs}{in^2} = 266.67 \text{ PSI}$

2. We have:

$Pressure = 800 \text{ PSI}$

$Area = \frac{1}{2} in^2 = 0.5 in^2$

We know that:

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

$Area*Pressure = Force$

Plug in what we know:

$Force = 800*0.5 = \frac{800}{2} = 400 \text{ lbs.}$

3. We have:

$Force = 800lbs$

$Pressure = 400 \text{ PSI}$

We know that:

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

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

Plug in what we know:

$Area = \frac{800}{400}$

$Area = 2 in^2$

And there you go.