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In addition to the dimensions of an object - length,
width, height, radius and so on - measurements of
how much stuff an object is made and how much space
the stuff fills are also measured. Stuff can be
anything: hydrogen gas, solid iron, water molecules.
An object that contains a certain amount of stuff is
said to have mass, and mass is measured by grams,
kilograms, and so forth. Do not confuse weight with
mass. Generally, weight is measured by pounds,
ounces, and so on. Mass = measure of the amount of
matter within an object
Weight = measure of an object along with the effect
of gravity. The chart below demonstrates the
difference between mass an weight as compared to
location. Let's say I weight 70 kg (I wish):
The amount of "stuff" in my body remains the
same, thus 70 kg but gravity affects how much I
weigh.
A White Dwarf
is a very massive stellar
remnant, thus my weight will be incredibly high.
On
Earth, there is 2.2 pounds per kilograms. For
pounds to kilograms, divide by 2.2. Density and
mass provide physical dimensions of a given object,
but are completely different in application. While
mass measures the total amount of stuff, density is
how much individual particles of stuff are within a
small space within the object. It is common for
density measurement to be based on a centimeter
cubed (cm3).
Density represents the mass (or number of particles)
per unit volume of a substance, material, or object.
The chart below demonstrates two types of density:
mass and particle. Mass density is the mass of an
object per cm3
and particle density is how many particles there are
in the same space.
| Matter |
Mass Density (g/cm3
) |
Particle Density (parts
per cm3 ) |
| Water |
1 |
3.7 x 1022 |
| Lead |
11.3 |
3.3x1022 |
| Gold |
19.3 |
5.9x1022 |
| Interstellar Space |
2x10-24 |
1 |
The three states of matter (solid, liquid and gas)
also affect density.
If density and the space filled is known, it is
possible to determine mass by the formula:
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