density notes test – thursday, 11/7 textbook & online resources: chapter 8 – lesson 1:...
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Density Notes
Test – Thursday, 11/7
Textbook & Online Resources:Chapter 8 – Lesson 1: Measuring Matter
Mass
• The amount of matter in an object.
Mass
• Mass is measured in grams or kilograms.• The tools that you use for measuring mass are
a triple-beam balance or a scale.
Weight
• The force of gravity pulling down on an object.
• On planet earth, an object’s weight is the same as its mass.
Weight = 6,000 kg Mass = 6,000 kg
• However, an object’s weight can change, depending on the amount of gravity.
• Ex: weight would change in space or on another planet
Weight = 2,262 Kg Weight = 14,184 Kg
Earth = Weight = 6,000 Kg
Weight = 0 Kg
*Empty Space*
Volume
• The amount of space that is taken up by an object.
Volume
• Volume is measured in cubic centimeters (cm3) or cubic meters (m3)
• Volume of liquids is measured in milliliters (ml) or Liters (L)
Volume of a box
• Length X width X height = volume
8 cm3 cm
4 cm
8cm X 3cm X 4cm = 96 cubic centimeters
Water Displacement
• Used to find the volume of an irregular solid….like this toy dinosaur
• Measure the water level with and without the dinosaur
• ***Difference in volumes = volume of the object!
• water level with object – water level without object = volume of object
10
10
20
30
40
50
60
70
80
90
100
0
Graduated Cylinder with out marbles
1010
20
30
40
50
60
70
80
90
100
0
Cylinder with marbles
77 – 47 = 30 cm3
Density
• The formula for density is D=m/v
• OR Density = mass
volume
Don’t forget the formula for density, or you will break Mrs. Szerdy’s heart!
MV
1. If the object has a mass of 74 grams, and a volume of 8 cm3 What is the density?
• 74g/8 cm3 = 9.25 g/cm3
2. If the object has a mass of 10 grams, and a volume of 20 cm3 What is the density?
• 10g/20 cm3 = 0.5 g/cm3
The Density Formula
X
If the object has a mass of 40 grams, and a volume of 5 cm3 What is the density?
D = ???? V = 5
M = 40
X
40g/5 cm3 = 8 g/ cm3
If the object has a density of 8 g/cm3 and a volume of 5 cm3, What is the mass???
D = 8 V = 5
M = ????
X
8g/cm3 X 5 cm3 = 40 g
If the object has a mass of 40 g and a density of 8 g/cm3, what’s the volume?
D = 8 V= ????
M = 40
X
40g 8 g/cm3
= 5 cm3
3. If the object has a density of 2 g/cm3 and a volume of 10 cm3, What is the mass?
• 2 g/cm3 x 10 cm3 = 20 g
4. If the object has a density of 0.5 g/cm3 and a volume of 25 cm3, What is the mass?
• 0.5 g/cm3 x 25 cm3 = 12.5 g
5. If the object has a mass of 60 g and a density of 3 g/cm3, what’s the volume?
• 60g / 3 g/cm3 = 20 cm3
6. If the object has a mass of 150 g and a density of 5 g/cm3, what’s the volume?
• 150g / 5g/cm3 = 30 cm3
• Density is measured in grams per cubic centimeter = g/cm3
• If something has a density of 10 g/cm3, that means that 1 cm3 of the substance would weigh 10 grams.
• Density is how heavy something is in relationship to its size.
• Density Gizmo – predict float or sink
• A small object can have high density.
• Ex: a coin is heavy for its size and will sink in water.
• A small object can have low density.
• Ex: a balloon is light for its size and will float in water or air.
• A large object can have high density.
• Ex: a boulder is very heavy for its size and will sink in water.
• A large object can have low density.
• Ex: an elephant is less heavy for its size and will float in water.
• Objects with a density of less than 1 float in water
***The density of water = 1***
• Objects with a density of more than 1 sink in water
Will it float?
• Mass = 52 g• Volume = 35 cm3
52g / 35 cm3 = 1.48 g/cm3
Will it float?
• Mass = 270 g• Volume = 317 cm3
270g / 317 cm3 = 0.85 g/cm3
Will it float?
• Mass = 4 g• Volume = 10 cm3
4g / 10 cm3 = 0.4 g/cm3
• A material’s density can be used to identify it.• The density of gold is 19.3 g/cm3
• Which of the following substances is gold?
Rock AMass = 108 gVolume = 12 cm3
Rock BMass = 126 gVolume = 15 cm3
Rock CMass = 386 gVolume = 20 cm3
108g / 12 cm3 = 9 g/cm3
126g / 15 cm3 = 8.4 g/cm3
386g / 20 cm3 = 19.3 g/cm3
Find the density of these 3 pieces of gold
Small Piece of GoldMass = 386 gVolume = 20 cm3
Medium Piece of GoldMass = 1158 gVolume = 60 cm3
Large Piece of GoldMass = 5018 gVolume = 260 cm3
386g / 20 cm3 = 19.3 g/cm3
1158g / 60 cm3 = 19.3 g/cm3
5018g / 260 cm3 = 19.3 g/cm3
A material’s density is always the same! It does NOT change with its size.
• All samples of gold have the same density!!! It does not matter how large the piece is.