Density Problems
1. What is the formula for density?
mass divided by volume (m/v)
2. What is the density of an object with mass 50 kg and volume 100 m3?
0.5 kg/m3
3. What is the density of water?
1 g/m3
4. Explain why wood floats on water and a rock sinks in terms of density.
wood has a density less than water, rocks have a density greater than water
5. What is the density of an object with mass 1000 g and volume 10 cm3?
100 g/cm3
6. Will an object whose density is equal to the density of water sink or float?
it will float within the water
7. Explain why the atmosphere lies on top of the oceans in terms of density.
the atmosphere is less dense than the oceans
8. Use the table below to find the densities of the objects and order them in the column
below. Don’t forget to write the units of density in your answers (g/cm3)!
OBJECT
wood
metal
oil
water
plastic
MASS (g)
0.25
100
0.5
1
1.2
Most Dense
↓
↓
↓
Least Dense
metal
plastic
water
oil
wood
VOLUME (cm3)
1
1
1
1
1
Density = 100 g/cm3
Density = 1.2 g/cm3
Density = 1 g/cm3
Density = 0.5 g/cm3
Density = 0.25 g/cm3
9. Ice floats on top of water, yet ice is water in solid form. Explain why ice floats on
liquid water in terms of density? Can you describe what happens to the molecules
of water in ice to explain why it floats on liquid water?
ice is less dense than liquid water; there are less molecules per unit volume (mass
decreases) in ice
10. If you increase the mass of an object what does that do to the objects density?
density increases
11. If you decrease the volume of an object what does that do to an objects density?
density increases
12. What are two ways you could decrease the density of an object?
decrease the mass
13. The density of some stars can be as great as 4000 pounds per cm3 (about 2 tons
in a tablespoon!). What must have happened to such stars to explain such density?
the star collapsed upon itself