1. Lesson 35 - What is Density?
Density and Fluids
What Affects Density?
How to Calculate Density?

2. The Big Idea!!!
Density is a measure of how many particles, and how much mass is packed into a specific volume!

3. Different Densities
Less Dense
More Dense
 Click on hyperlinks

4. Readings
Use pages in the Science Focus 8 Textbook to help you complete the worksheet.
Use pages in the Science in Action 8 Textbook to help you complete the worksheet.

5. What is Density?
Density is the measurement of the amount of matter in a given area
Density is the description of the “crowdedness” of the particles that make up matter
Explain this picture… how can she float so easily?

6. What is Density?
The density of a substance is related to its physical properties
Remember that all matter is made up of tiny particles and that different matter consists of different types of particles
Well, the particles of one substance may interact differently than another causing them to be closer together, heavier, or stronger attractions, all which cause the substance to be more dense

7. Properties of Density
Walking through water is harder than walking through air
This is because the density of the water is greater than that of air
The particles are more closely packed together and they have stronger attractive forces to break

8. Properties of Density
Generally we say that gases are less dense than liquids, and liquids are less dense than solids
This is because the particles are generally packed together tighter in solids than they are in liquids or gasses
Is this always true all of the time?

9. Properties of Density
Sometimes we find that solids are less dense than liquids
Look at the examples below

10. Properties of Density
In these cases, the particles of the fluids are more dense than the solids they support

11. Density Diagram
Below are two volumes of equal size and capacity filled with the same type of particle
Which one is more dense?
How do you know?

12. Density Diagram The box on the right is denser because it is heavier
More particles (of the same substance) = more mass = more dense

13. Density Diagram
If the particles on the left weigh 4 times more than the particles on the right, which box is more dense now?

14. Density Diagram Blue particles are 4 times heavier than red particles
8 blue particles means you would have to have 32 red particles to be equal (8 x 4 = 32)
But there are only 24 red particles so the box on the left has more mass meaning it’s more dense

15. Density Diagram
If these two different substances were liquids and they were mixed, which would settle out on the bottom and which would settle out on the top?

16. Density Diagram
If these two fluids were mixed then the heavier substance (blue particles) would settle out on the bottom

17. Fluids on Fluids
Because the particles making up the oil are less dense than the water particles, the oil settles out on top of the water
Lets look at this example with a few more different density liquids like:
Soap, oil, & water

18. Changing Density
Just like with diffusion and viscosity, the one factor that can change density is TEMPERATURE
Temperature can affect the density of a substance by causing the particles to move faster and further apart
By expanding the space between the particles, you are increasing the volume which affects density

19. Changing Density
Just like in a hot air balloon, we heat the air which causes the particles to expand and spread apart until it becomes less dense than the cold air
The change in density can be great enough that the balloon will become less dense even with the basket and passengers

20. Density vs. Temperature
Lets look at the Density Thermometer…
What is happening to the density of the water particles within the thermometer as it is cooled?
What is happening to the density of the water particles within the thermometer as they being to warm back up?

21. Your Assignment
You are being handed a short worksheet that deals with Density
Use your notes to answer the questions that on the worksheet