Density

1
Density
What is it?
How can I calculate it?
2
Example

• What is the density of an object that has a mass
  of 20 g and a volume of 5 cm3.

3
Work

• Density Mass
• Volume
• Density 20 g
• 5 cm3
• Density 4 g/cm3

4
Your Turn

• Now lets take some time to measure the density
  of some items.
• What do you need to measure to determine the
  density of an item?
• What equipment will you need?

5
Does This Make Sense?

• Mr. McNamara invented a new type of peanut butter
  candy that you eat after disco dancing. He
  measures the mass to be 25 g and the volume to be
  5 cm3. He calculates that the density is 0.20
  g/cm3. When he places it in a beaker full of
  water it sinks.

6
Analysis

• Since it sinks in water, what does that tell you
  about the density of the item?
• What is the actual density of the new peanut
  butter candy?

7
New Setting

• You are going swimming in the Dead Sea. You walk
  to the edge of the water and see the following
  people in the water.

8
Picture One
9
Picture Two
10
Picture Three
11
Questions

• How could this happen?
• How is it related to density?
• How is it related to the egg?

12
Density Definitions

• Density is the mass per unit volume of an object.
  
• It tells us how closely packed the matter is in
  an object.
• The denser the object, the closer together the
  matter is.
• It can help us identify the type of matter that
  we have.

13
Reminder

• Mass is the amount of matter in an object.
• Volume is the amount of space an object takes up.
  

14
Question

• A block has a mass of 55 g and occupies a space
  of 44 mL. What is the density of this object in
  g/mL?
• What would happen to this block if we placed it
  in pure water at 20 degrees Celsius?

15
Work

• Density Mass
• Volume
• Density 55 g
• 44 mL
• Density 1.25 g/mL

16
Block in Water

• Since the block has a density greater than 1
  g/mL, it would sink in pure water at 20 degrees
  Celsius.

17
Question

• What would happen to the density of this block if
  you were to cut it in half?
• What would happen to this block if we placed it
  in pure water at 20 degrees Celsius?

18
Work

• Density Mass
• Volume
• Density 27.5 g
• 22 mL
• Density 1.25 g/mL

19
Block in Water

• Since the block still has a density greater than
  1 g/mL, it would sink in pure water at 20 degrees
  Celsius.

20
Another Question

• What is the density of this rock if it has a mass
  of 120g?

21
Work

• Density Mass
• Volume
• Density 120 g
• 50 mL
• Density 2.4 g/mL

22
Questions

• Look at the picture to the right. It is supposed
  to be a graduated cylinder with different liquids
  in it. Write down the order of the liquids from
  the least dense to the most dense.

23
Questions
Least Dense
Most Dense
24
Questions
As you move down through the liquids, the liquids
get denser.
25
Questions
As you move up through the liquids, the liquids
get less dense.
26
Questions
A block is placed into this graduated cylinder.
What can you say about the density of this block?

27
Questions
The density of this green block is greater than
the density of the red and black liquids, but
less than the density of the blue, gray and
yellow liquids.