# Mass, Density, And Volume (what units?)

• May 14th 2011, 07:21 AM
Dug
Mass, Density, And Volume (what units?)
Volume = 45 cubic meters
Density = 1900 kg/cubic meters
Mass = (45)(1900) = 85500

is the unit in kilograms?
because in this site> DENSITY
it says tons. i'm confused.
• May 14th 2011, 07:27 AM
TheEmptySet
Quote:

Originally Posted by Dug
Volume = 45 cubic meters
Density = 1900 kg/cubic meters
Mass = (45)(1900) = 85500

is the unit in kilograms?
because in this site> DENSITY
it says tons. i'm confused.

We know that mass is equal to density times volume

In symbols we have

$\displaystyle m=\rho V$

So density must be

$\displaystyle \rho =\frac{m}{V}$

Density can have any units of mass divided by volume. In the SI system it is common to have Kilograms per cubic meter, but others are often used as well.
• May 14th 2011, 07:37 AM
Dug
Quote:

Originally Posted by TheEmptySet
We know that mass is equal to density times volume

In symbols we have

$\displaystyle m=\rho V$

So density must be

$\displaystyle \rho =\frac{m}{V}$

Density can have any units of mass divided by volume. In the SI system it is common to have Kilograms per cubic meter, but others are often used as well.

Thanks. But in that specific problem, is 85500 in kilogram units? because that's just the first part.
The whole problem is this:
A building organization has to transport a conical heap of sand. How many 3-ton dumpers are required to transport the sand if the measurements gave the following results: the length of the circumference of the base circle is equal to 35.2m, the generator to 9.5m? each dumper has to carry five trips.. the density of sand equals 1.9x10^3 kg/m^3
• May 14th 2011, 07:55 AM
TheEmptySet
Quote:

Originally Posted by Dug
Thanks. But in that specific problem, is 85500 in kilogram units? because that's just the first part.
The whole problem is this:
A building organization has to transport a conical heap of sand. How many 3-ton dumpers are required to transport the sand if the measurements gave the following results: the length of the circumference of the base circle is equal to 35.2m, the generator to 9.5m? each dumper has to carry five trips.. the density of sand equals 1.9x10^3 kg/m^3

First a metric tonne is gives by

$\displaystyle 10^3 kg=1 \text{ metric tonne }$

Tonne - Wikipedia, the free encyclopedia

You can find the radius of the circle using the formula

$\displaystyle C=2\pi r$

Quote:

the length of the circumference of the base circle is equal to 35.2m, the generator to 9.5m?
I have no idea what you mean by the part of this sentence after the comma. I hope it is some how related to either the height or the slant height of the cone.