Boyle's Law, Charles' Law, Archimedes Principal: Properties of Liquids and Gases

1. Chapter 17.2 and 17.3
Notes
Mrs. Neistadt
Physical Science

2. Chapter 17.2 Notes
• DQ: Concept Review Question #4:
Would a cube of solid silver sink or float in liquid
silver? How do you know? (pg 301)
– Solid silver is more dense than liquid
silver. A solid silver rock would sink if
dropped into a liquid pool of silver.
• Liquids tend to be less dense than when in
their solid form.

3. 17.2 Density of Fluids
• The mass is the same- but in liquids, the
atoms are able to spread out, which
makes their volume bigger.
• The atoms are spread out causing most
liquids to be less dense than solids.

4. 17.2 Density of Water
• *Water is an exception.
– *Ice is less dense than liquid water, so ice
floats.
– Water molecules are more tightly packed
when in liquid form.

5. 17.3 Buoyancy of Fluids Notes
• *What is buoyancy?
• *Buoyancy- is the measure of upward
force a fluid exerts on an object.

6. Archimedes’ Principle
In third Century BC, a Greek Mathematician
named Archimedes discovered:
• *The force exerted on an object in
liquid is equal to the weight of the fluid
displaced by the object.
• *This relationship is called
Archimedes’ Principle

7. Archimedes’ Principle
in action:

8. What is Buoyancy?

9. *Buoyancy and Gases
• *In 1787 Jacques Charles discovered a
principle that describes the forces that
allow gases to float.
• This force explains why balloons filled with
helium or hot air will float.

10. Buoyancy and Gases
• *Charles’ Law- The volume of gas
increases with increasing temperature; the
volume of gas decreases with decreasing
temperature

11. Examples of Charles’ Law:
• Soccer ball left outside on cold night
• Bicycle/Car tires in the winter
• Party balloons left in a hot car

12. Boyle’s Law
• A law explaining the relationship between
gas, pressure and volume is Boyle’s Law.
• You see Boyle’s Law in action when you
observe gases under high pressure:
– Fire extinguishers
– Spray cans
– Even volcanoes!

13. Boyle’s Law
*Boyle’s Law- as the pressure of a gas
increases, its volume decreases; as the
pressure of a gas decreases, its volume
increases.

14. Charles Law & Boyle’s Law

15. *Properties of Liquids
• *Viscosity is the measure of a material’s
resistance to flow. H
– High Viscosity= high resistance to flow i
Ketchup, yogurt, honey
g
– Low Viscosity= low resistance to flow
h
oil, water, juice
Low

16. Why are some liquids more
viscous?
• *The shape of the molecules in the liquid
determine the viscosity.
• Bigger, bumpier molecules = more
viscosity
• *The temperature of the liquid also
determines viscosity.
• Higher temperature = less viscosity (pours quickly)
• Lower temperature = more viscosity (pours slowly)

17. Examples of Viscosity:

18. Summarize:
Explain in your own words:
• Explain these ideas and give
examples of each:
1.Archimedes’ Principle.
2.Boyle’s Law.
3.Charles’ Law.