Making Measurements and Calculating Density

1
Making Measurements and Calculating Density

• Pay attention, this will make lab one and two a
  breeze.

2
Measuring Length

• Know which side is Metric.
• Metric system is a base 10
• 1 cm 10 mm
• 1 m 100cm 1000mm
• Units change but the distance is the same.

3
Measuring Length

• What is the length of the pen? Round to the
  nearest whole cm.
• 14 cm
• Now round to the nearest tenth of a cm.
• 13.8 cm

4
Measuring Mass

• Find mass using a balance.
• Mass is different than weight.
• Weight is caused by the force of gravity.
• Mass is the amount of matter that makes up an
  object.

5
Measuring Mass

• Move the three masses to find the mass of an
  object.
• This mass tells you 10s of grams.
• This mass tells you 100s of grams.
• This mass tells you ones and tenths of a gram.

6
Measuring Mass

• First place the object on the balance.
• Then move the masses until they are equal.
• Make sure the marks line up.

7
Measuring Mass

• What is the mass of the rock? Round to the
  nearest tenth.
• 134.7 grams

8
Measuring Volume

• Use a graduated cylinder.
• Most common units are liters and milliliters.
• What is the volume of the liquid in milliliters?
• 385 ml

9
Measuring Volume

• Use water displacement to find the volume of an
  irregular shaped object. Like a rock.
• Volume before was 385 ml
• After rock was added.
• 440 ml
• Rocks volume 55 ml

10
Calculating Density

• Use the formula Density mass volume
• Density of the rock mass 134.7 g volume 55 ml
• Density 2.4 g/ml

11
Float or Sink, what controls it?

• Density
• Any object that is denser than its surroundings
  will sink.
• Any object that is less dense compared to its
  surroundings will float.

12
Paper Demo of Density

• Does the paper have a mass?
• YES
• Does the paper have a volume?
• YES
• Can we calculate a density?
• YES

13
Paper Demo of Density

• What happened to the density after the paper was
  altered?
• It remained the same
• Copy down the example if you dont get it.

14
Shape and Density

• Are the objects the same shape?
• YES
• Do they have the same mass?
• NO
• Do they have the same density?
• NO

Reason different materials have different
densities.
15
Temperature and Density

• What happens to something if you heat it?
• IT EXPANDS
• Takes up more space
• Larger volume
• If volume increases, density decreases.
• Example --

16
Pressure and Density

• How did the volume of the ball change?
• It Decreased
• What force did you use?
• Pressure
• So if you increase pressure the volume will
• Decrease
• If the volume decreases, the density will
• INCREASE

17
Phases of Matter and Density

• Three phases of matter from most to least dense.
• SOLID, LIQUID, GAS
• Is this the same for water?
• NO
• Most to least dense for water.
• LIQUID, SOLID, GAS
• Ice floats!