DENSITY
By: Lim Yuet Tung
1O2 (24)
WHAT IS DENSITY?
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A material's density is defined as its mass per
unit volume.
A measurement of how tightly matter is
crammed together.
The principle of density was discovered by the
Greek scientist Archimedes.
Density is also called as (rho).
HOW DOES DENSITY DISCOVERED?
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In a well-known tale, Archimedes was given the
task of determining whether King Hiero's
goldsmith was embezzling gold during the
manufacture of a wreath dedicated to the gods
and replacing it with another, cheaper alloy.
HOW DOES DENSITY DISCOVERED?
One day, Archimedes took a relaxing immersion
bath and observed from the rise of the warm
water upon entering that he could calculate the
volume of the gold crown through the
displacement of the water.
 Thus, after Archimedes found out that the king
has been cheated, then the density was known by
public.
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USES OF DENSITY
Hot air balloons
 Hot air is less dense than colder air, hence the
balloon will float up.
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USES OF DENSITY
Cooking
 We depend on the fact that steam or warmer air
is not very dense and thus takes heat away from
the food
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USES OF DENSITY
Boats
 Boats depend on density to stay aloft
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FORMULAE OF MASS, VOLUME AND
DENSITY
CHANGE OF DENSITY
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Density can be change by temperature and
pressure.
The increase of temperature will decrease the
density.
The increase of pressure will increase the
density.
CALCULATE DENSITY
From the picture, we can
easily know that substance
“A” has the lowest density
while the liquid “F” has the
highest density as the
object
with more density will sink
while the object with less
density will float.
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CALCULATE DENSITY
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The following steps show how to calculate density
of a regular object.
I.
II.
III.
IV.
Find the mass of the object.
Calculate the volume of the object.
Use the mass of the object and divide it by the
volume of the object.
Repeat the experiment about 3 to 5 time and
find the average of the density to make the
answer more accurate.
CALCULATE DENSITY
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The following steps show how to calculate density
of an irregular object.
I.
II.
III.
IV.
V.
VI.
Weigh the object to determine its mass
Pour water into a measuring cylinder and read
its volume and write it down as V1.
Tie the object with a piece of string and lower it
into the water. Note the volume reading as V2.
The volume of the object is equal to (V2 – V1)
Use the mass of the object and divide it by the
volume of the object.
Repeat the experiment about 3 to 5 time and
find the average of the density to make the
answer more accurate.
HOW TO CALCULATE THE DENSITY OF AN
ALLOY?
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Alloy is an object which mix by two or more
elements.
I.
II.
III.
Calculate the total amount of mass of the two
element.
Calculate the total amount of volume of the two
element.
Divide its total mass by total volume and get
the density of the alloy.
WHAT MUST WE DO TO AVOID ERROR
WHEN CALCULATE DENSITY?
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Make sure that the measurement that you are
using starts on “0” to avoid any zero errors.
Avoid parallax errors when reading the volume of
an object inside a measuring cylinder.
Repeat the experiment about 3 to 5 time and find
the average to make the answer more accurate.
DENSITY DEMONSTRATION: COKE VS.
DIET COKE
Materials:
 12 ounce coke can
 12 ounce diet coke can
 water
 fish tank
 sugar
 nutria sweet
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DENSITY DEMONSTRATION: COKE VS.
DIET COKE
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Place the regular coke and the diet coke into the
water.
You will find that the diet coke will float on the
water but the regular coke will sink into thee
water.
DENSITY DEMONSTRATION: COKE VS.
DIET COKE
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The Density of water is 1g/cm3. An object will
float is the density is less than 1. An object will
sink if its density is greater than 1.
We know that regular coke will sink but diet coke
will float as nutria sweet is lighter than sugar .
Also try this on different brands of sodas for
example Pepsi, Dr. Pepper, Sprite, etc.
DENSITY FOR SOME COMMON MATERIALS
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water
Glass
Granite
Bone
Human body
Butter
Ice
Carbon
Kerosene
Chalk
Salt
Coal
Sand
Cork
Sulfuric Acid
Gasoline
1.00
2.60
2.65
1.85
0.995
0.94
0.917
2.60
0.80
2.36
2.20
1.50
2.80
0.25
1.84
0.72
DENSITY FOR SOME COMMON METALS
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Aluminum
Brass
Chromium
Copper
Gold
Iron
Lead
Magnesium
Mercury
Nickel
Platinum
21.50
Silver
Tin
Uranium
Zinc
2.70
8.40
7.10
8.63
19.30
7.80
11.30
1.74
13.60
8.80
10.40
7.30
18.70
6.90
BIBLIOGRAPHY
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www.about.com
http://www.elmhurst.edu/~chm/vchembook/121A
densitycoke.html