# Homework Help: Density help required

1. Feb 18, 2008

### SiCharlton

Hi all,
My problem is concerning density and how to calculate it. Basically, calculating density of a concrete cube. I've been given;

Weight (kg) In Air - 2.345,2.340
In Water - 1.348, 1.360

Dimensions - Height - 1900mm
Width - 320mm
Depth - 180mm

I need to calculate the Density kg/m^3

Does it include the specific gravity etc..? I've searched google for ages but to no avail. Could it be, Weight in air/(weight in air - weight in water) to give S.G, thus 2.35...therefore a ratio 1:2.35 of water to cement. Taking density of water as 1000kg/m^3, density of concrete is 2350kg/m^3?

Any help will be really appreciated.

Thanks
Simon

2. Feb 18, 2008

### mgb_phys

You seem to have been given rather too much information. If you have the dimensions and the weight in air then you have the density ( simply mass / volume )
Be carefull of the units.

If you wanted to be really picky you could include the bouyant effects of the air - although this wouldn't be worth it given the accuracy the dimensions are quoted to.