# Homework Help: Simple volume/mass calculation

1. Sep 9, 2008

### metalmagik

1. The problem statement, all variables and given/known data
An Olympic-size pool is 50.0 m long and 25.0 m wide.
(a) How many gallons of water (d=1.0 g/mL) are needed to fill the pool to an average depth of 4.8 ft?
(b) What is the mass (in kg) of water in the pool?

2. Relevant equations
density = m/V

3. The attempt at a solution
I almost got all of Part (a). Here's what I did:

4.8 ft x .3048m/ft = 1.46304 m

After converting the depth in feet to depth in meters, I multiplied:

1.46304 m x 50 m x 25 m = 1828.8 cubic meters.

From here I do not know how to get that Volume into gallons. I think it might work if I convert to cubic feet, then to gallons? Is that right? Once I have that I know all I have to do is use the density formula to get the mass. Help please!

2. Sep 9, 2008

### Staff: Mentor

How many litres per galon? How many liter per cubic meter?

You don't need galons for the mass. What you have to do is to either convert cubic meter to mililiters or density from g/mL to kg/cubic meter.

3. Sep 9, 2008

### metalmagik

oh okay I see. For an answer I got 18285.335. I found the conversions for gallons to L and then to mL anyway, and then I used that in d = m/V and converted to kg when I got my answer in g. Please let me know if this is not correct :-X thanks so much for your help!

4. Sep 10, 2008

### Staff: Mentor

Significant digits!