1. DENSITY

2. D=m/v D = density, What Is Density?
Density is how heavy something is for its size.
Density is mass divided by volume or
D=m/v D = density,
M = mass
V = volume

3. Another Way of Looking at It.
You will often hear density referred to as “mass per unit volume.”
Let’s break this down:
Mass = how much matter the object has.
Per = means divided by
Unit volume = how much space it takes up

4. Take the mass and divide by its volume! So…
When you hear mass per unit volume, you should think…
Take the mass and
divide by its volume!

5. What Are the Units of Density?
Mass units would include
Grams for very small objects or
Kilograms for larger objects
Volume units would include
Cubic centimeters for small objects or
Cubic meters for large objects
Milliliters for small amounts of liquids
Liters for larger amounts of liquid
Lets stick to grams and cubic centimeters for now.

6. How to State Density Units
mass
You have grams for
You have cubic centimeters for
These are not the same units, they don’t cancel so you have to include both units in your answer
volume

7. How to State Density Units
The units of density are:
Grams/Cubic Centimeter or
g/cm3

8. length multiplied by width multiplied by height or
Why Cubic Centimeters?
Remember that volume is
length multiplied by width multiplied by height or
l X w X h
In each case, the distance is in cm and since you are multiplying it three times, you get cubic centimeters.

9. Now, How About an Example?
l=10 cm
h=5 cm
w=2 cm
Mass= 100 grams
Use the information provided to calculate the density of the object

10. What Did You Get? If you got 1g/cm3, you are correct!
Lets see how this works:
V=l x w x h
V=10 cm X 5 cm X 2 cm
V=100cm3
Mass = 100 g (given)
D=m/v
D=100 g/100cm3=1g/cm3

11. A Word About Irregularly Shaped Objects.
If you are given an irregularly shaped object and told to find the density, you might have a problem.
If the length, width, and height of the object are not uniform (the same), you cannot use l X w X h to determine volume.

12. A Word About Irregularly Shaped Objects.
To determine the volume of an irregularly shaped object, start with a graduated cylinder of water filled about half full
Record the volume of water in the cylinder
Drop in the irregularly shaped object
Record the volume of water in the cylinder with the object in it
Subtract the original volume from the second volume to determine the volume of the object

13. A Word About Irregularly Shaped Objects.
You are measuring the amount of water displaced by the object which is equal to the volume of that object
This is called:
Volume
By Displacement

14. g/cm3 Liquids Milliliters Or liters
So far we have been talking mostly about solids. Solids have densities that can be easily expressed in
Liquids tend to be measured in
This is not a problem because you can convert milliliters or liters into grams per cubic centimeter.
g/cm3
Milliliters
Or liters

15. Liquids
You can also weigh a liquid to determine its mass. Now we are going to use the word massing for weighing to avoid confusion
To do this, measure your cylinder in grams and record its empty mass
Add your liquid
Now mass the cylinder again
Subtract the mass of just the cylinder and you have the mass of your liquid

16. Can you guess what kind of solid would sink in water?
Sink or Float?
Solids can float or sink in a liquid.
Can you guess what kind of solid would sink in water?

17. Answer:
Any solid will sink in water if it has a density greater than the density of water.
Water has a density of
Any solid with a density greater than 1g/cm3 will sink in water!
1g/cm3