Density Problems: Use Pages 424-429 in Your Textbook If You Need to Review Density

Density Problems: use pages 424-429 in your textbook if you need to review density.

1. What is the formula for density? What is the SI unit of density?

2. What is the density of an object with mass 50 kg and volume 100 m3?

3. The density of water is 1 g/cm3 = 1 g/ml. Explain why wood floats on water and a rock sinks in terms of the density of water.

4. What is the density of an object with mass 1000 g and volume 10 cm3?

5. Will an object whose density is equal to the density of water sink or float?

6. Explain why the atmosphere lies on top of the oceans in terms of density.

7. 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 MASS (g) VOLUME (cm3) wood 0.25 1 metal 100 1 oil 0.5 1 water 1 1 plastic 1.2 1

Most Dense ______Density = ______↓ ______Density = ______↓ ______Density = ______↓ ______Density = ______Least Dense ______Density = ______

8. Ice floats on top of water, yet ice is water in solid form and most solids sink in liquids. 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?

9. If you increase the mass of an object what does that do to the objects density?

10. If you decrease the volume of an object what does that do to an objects density?

11. The density of neutron 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? Hint: think back to what your learned about stellar evolution earlier this year.