1. DENSITY Q) Which weighs more:-
A kilogram of feathers or a kilogram of iron?
DENSITY

2. Density is the Mass per unit Volume
What is Density?
If you take the same volume of different substances, then they will weigh different amounts.
Wood
Water
Iron
1 cm3
1 cm3
1 cm3
IRON
0.50 g
1.00 g
8.00 g
Q) Which has the greatest mass and therefore the most dense?
Density is the Mass per unit Volume

3. Density Equation: = m V m V  Mass Density = Volume Example:
g or kg m V 
Mass
Density =
Volume
gcm-3 or kgm-3
cm3 or kg3
= m V
Example:
Q) Liquid water has a density of 1000kgm-3, while ice has density of 920kgm-3.
Calculate the volume occupied by 0.25kg of each.
V = m = 0.25 = m3 
V = m = 0.25 = m3 

4. DENSITY OF A REGULAR SOLID
Find the Mass of the solid on a balance.
Measure the three lengths and calculate the Volume.
(ie V = l x w x h )
Calculate the Density.
m = 240 g
2.0 cm
 = m = 240 =10.0 g/cm3 V
3.0 cm
4.0 cm

5. DENSITY OF AN IRREGULAR SOLID
m = 360 g
 = m = 360 =12.0 g/cm3 V
Find the Mass of the solid on a balance.
Fill the Measuring Cylinder with Water to a known Volume.
Add the Object.
Work out the Volume of Water that is displaced.
Calculate the Density.
80 cm3
50 cm3

6. DENSITY OF AN IRREGULAR SOLID
OR use a Eureka Can to find the Volume.
Find the mass of the solid on a balance.
Add water until just overflowing.
Place a Measuring Cylinder under the spout.
Add the Object.
Collect the Water and read off the Volume.
Calculate Density
m = 440 g
40.0 cm3
 = m = 440 =11.0 g/cm3 V

7. DENSITY OF A GAS
Remove the air from a flask of a known Volume, using a vacuum pump.
Find its Mass.
Add the gas to be tested.
Reweigh.
The difference is the Mass of gas.
Calculate Density.
To vacuum flask
150.0 g
170.0 g
1000 cm3
= 20.0g
 = m = 20 = g/cm3 V

8. Aluminum 3 1 6 2.70 Iron 1.50 0.62 2.62 Brass 0.25 4 8.50 Wood 2 0.40
Material
Mass
in g
Length
in cm
Width
Height
Volume
in cm3
Density
in g/cm3
Aluminum 3 1 6
2.70
Iron
1.50
0.62
2.62
Brass
0.25 4
8.50
Wood 2
0.40
0.50
Slate
0.92
2.20
2.80
Glass 8
.75 11
2.50
Lead
0.05 20 10
11.30
Marble
13.5 5
Wax
97.9
1.25

9. Material
Mass
in g
Length
in cm
Width
Height
Volume
in cm3
Density
in g/cm3
Aluminum
0.45 3 1 2 6
2.70
Iron
1.50
2.82
0.62
2.62
1.14
Brass 34 16
0.25 4
8.50
Wood
0.40
0.625
.50
0.50
Slate
0.92
0.88
2.20
0.18
2.80
Glass 8
0.39
.75 11
3.2
2.50
Lead
113
0.05 10 20
11.30
Marble
13.5
0.29 5
Wax
97.9
4.40
1.25
8.9

10. Density as a Function of Temperature
For most substances,
as temperature increases
the volume increases
and as a result the density decreases.