Density is measured as the mass of an object divided by its volume. For example, if an object
with a volume of 50cm3 weighs 30 g, its density is 30÷50 g/cm3, which is 0.6 g/cm3.
Density determines whether a substance will sink or float when placed in a second substance. The substance with less density will always float.
Use the information provided to answer the questions below.
Find the density of the following:
Substance
Volume in cm3
Mass in g
Gasoline
5
3.5
Milk
10
10.3
Gold
8
154.4
Aluminum
12
32.4
Water (at 4oC)
14
14
Water (at 20oC)
16
15.968
Ice (at 0oC)
20
18.4
Density in g/cm3
Think!
When milk is mixed with gasoline, which substance will float?
Why do ice cubes always float at the top of a glass of water?
How To Train Your Dragon © 2013 DreamWorks Animation LLC. All Rights Reserved.
If the density of iron is 7.8 g/cm3 and you find an iron nail weighing 15g, what would the
volume of the nail be?
In an ocean, the water is not the same temperature throughout. Do you think the surface is
warmer or cooler than the water at the bottom?
How does a hot air balloon work?
How To Train Your Dragon © 2013 DreamWorks Animation LLC. All Rights Reserved.
Answers
Density in g/cm3
Gasoline
Milk
Gold
Aluminum
Water (at 4oC)
Water (at 20oC)
Ice (at 0oC)
Think!
When milk is mixed with gasoline, which substance will float? Gasoline
Why do ice cubes always float at the top of a glass of water? 'Because the density of an ice cube
is less than that of water
If the density of iron is 7.8 g/cm3 and you find an iron nail weighing 15g, what would the
volume of the nail be? Volume = weight ÷ density =15 ÷ 7.8 = 1.92 cm3
In an ocean, the water is not the same temperature throughout. Do you think the surface is
warmer or cooler than the water at the bottom? The water at the top of the ocean is warmer
than the water at the bottom because cold water has a higher density than warm water and sinks
to the bottom.
How does a hot air balloon work? Burners heat the air inside the balloon. Since hot air is less
dense than cold air, the balloon begins to rise.
How To Train Your Dragon © 2013 DreamWorks Animation LLC. All Rights Reserved.