Unit 3 Lesson 2 Energy Transfer
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Hot and Cold
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How are energy and temperature related? • All matter is made up of moving particles and has
kinetic energy. • Temperature is a measure of the average kinetic
energy of particles. • The faster a particle moves, the more kinetic
energy it has.
Unit 3 Lesson 2 Energy Transfer
How are energy and temperature related? • Thermal energy is the total kinetic energy of
particles. • Thermal energy depends on the number of
particles. • The more particles there are in an object, the
greater its thermal energy.
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Unit 3 Lesson 2 Energy Transfer
How are energy and temperature related? • How does kinetic energy change as particle
motion increases and decreases?
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Unit 3 Lesson 2 Energy Transfer
What is thermal expansion?
• As the space between particles increases, a substance expands.
• The increase in volume that results from an
increase in temperature is called thermal expansion.
• Thermal expansion causes a change in the density
of a substance.
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Unit 3 Lesson 2 Energy Transfer
What is thermal expansion?
• Density is the mass per unit volume of a substance.
• Differences in density caused by thermal
expansion can cause movement of matter. • The movement of air in the atmosphere, water in
the oceans, and rock in the geosphere can be caused by thermal expansion.
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Unit 3 Lesson 2 Energy Transfer
Getting Warm
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What is heat?
• Heat is the energy that is transferred between objects that are at different temperatures.
• When objects at different temperatures come in
contact, energy is transferred between them until they reach the same temperature.
• Energy flows from the object at higher
temperature to that at lower temperature.
Unit 3 Lesson 2 Energy Transfer
Why can the temperatures of land, air, and water differ? • The different rates at which materials become
warmer or cooler are due to specific heat. • Materials with a high specific heat require more
energy to show an increase in temperature. • Water has a higher specific heat than land, which
means water warms up and cools down more slowly than land does.
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Unit 3 Lesson 2 Energy Transfer
Heat
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How is energy transferred by radiation?
• Radiation is the transfer of energy as electromagnetic waves.
• The sun transfers energy to Earth by radiation. • Radiation can transfer energy between objects
that are not in direct contact with each other.
Unit 3 Lesson 2 Energy Transfer
How is energy transferred by radiation?
• Energy from the sun travels as waves and is called electromagnetic radiation.
• Forms of electromagnetic radiation include visible
light, infrared radiation, X-rays, and ultraviolet light.
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Unit 3 Lesson 2 Energy Transfer
How is energy transferred by radiation?
• How does the sun heat Earth?
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Unit 3 Lesson 2 Energy Transfer
Where does radiation occur on Earth?
• The sun is almost 150 million km away from Earth, but it is the major source of energy for processes on Earth.
• Solar radiation is partly reflected and scattered by
Earth’s atmosphere. However, some solar radiation is absorbed by the atmosphere, geosphere, and hydrosphere.
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Unit 3 Lesson 2 Energy Transfer
Heating Up
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How is energy transferred by convection? • Convection is the transfer of energy due to the
movement of matter. • Convection occurs because most matter becomes
less dense when it gets warmer. • Convection currents form as warm and cool
matter rise and fall due to temperature and density differences.
Unit 3 Lesson 2 Energy Transfer
Where does convection occur on Earth?
• Energy moves through the atmosphere as warm air rises and cool air sinks.
• Ocean water has different densities due to
differences in temperature and the amount of salt in the water.
• Energy is transferred through rock material from
Earth’s core to the surface by convection currents.
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Unit 3 Lesson 2 Energy Transfer
Ouch!
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How is energy transferred by conduction? • Conduction is the transfer of energy from one
object to another object through direct contact. • When objects at different temperatures touch,
their particles interact.
• The faster-moving particles of the warmer object transfer energy to the slower-moving particles in the cooler object.
Unit 3 Lesson 2 Energy Transfer
Where does conduction occur on Earth?
• Energy is transferred by conduction from the warmer ground to cooler air at Earth’s surface.
• Warm air can transfer energy to cooler water and
cause evaporation. If water vapor transfers energy to the air, the water vapor may condense.
• Inside Earth, energy can be transferred between
rock particles by conduction, but very slowly.
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Unit 3 Lesson 2 Energy Transfer
Answers 115
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Unit 3 Lesson 2 Energy Transfer
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Unit 3 Lesson 2 Energy Transfer
Answers 118-119
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Unit 3 Lesson 2 Energy Transfer
Answers 120-121
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Unit 3 Lesson 2 Energy Transfer
Answers 122-123
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Unit 3 Lesson 2 Energy Transfer
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Unit 3 Lesson 2 Energy Transfer
Answers 126-127
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Unit 3 Lesson 2 Energy Transfer
Answers 126-127
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Unit 3 Lesson 2 Energy Transfer