Unit 3 Lesson 2 Energy Transfer Copyright © Houghton Mifflin Harcourt Publishing Company

Hot and Cold How are energy and temperature related? Unit 3 Lesson 2 Energy Transfer Hot and Cold 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. Copyright © Houghton Mifflin Harcourt Publishing Company 2

How are energy and temperature related? 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. Copyright © Houghton Mifflin Harcourt Publishing Company 3

How are energy and temperature related? Unit 3 Lesson 2 Energy Transfer How are energy and temperature related? How does kinetic energy change as particle motion increases and decreases? Copyright © Houghton Mifflin Harcourt Publishing Company 4

What is thermal expansion? 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. Copyright © Houghton Mifflin Harcourt Publishing Company 5

What is thermal expansion? 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. Copyright © Houghton Mifflin Harcourt Publishing Company 6

Getting Warm What is heat? Unit 3 Lesson 2 Energy Transfer Getting Warm 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. Copyright © Houghton Mifflin Harcourt Publishing Company 7

Why can the temperatures of land, air, and water differ? 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. Copyright © Houghton Mifflin Harcourt Publishing Company 8

Heat How is energy transferred by radiation? Unit 3 Lesson 2 Energy Transfer Heat 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. Copyright © Houghton Mifflin Harcourt Publishing Company 9

How is energy transferred by radiation? 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. Copyright © Houghton Mifflin Harcourt Publishing Company 10

How is energy transferred by radiation? Unit 3 Lesson 2 Energy Transfer How is energy transferred by radiation? How does the sun heat Earth? Copyright © Houghton Mifflin Harcourt Publishing Company 11

Where does radiation occur on Earth? 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. Copyright © Houghton Mifflin Harcourt Publishing Company 12

Heating Up How is energy transferred by convection? Unit 3 Lesson 2 Energy Transfer Heating Up 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. Copyright © Houghton Mifflin Harcourt Publishing Company 13

Where does convection occur on Earth? 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. Copyright © Houghton Mifflin Harcourt Publishing Company 14

Ouch! How is energy transferred by conduction? Unit 3 Lesson 2 Energy Transfer Ouch! 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. Copyright © Houghton Mifflin Harcourt Publishing Company 15

Where does conduction occur on Earth? 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. Copyright © Houghton Mifflin Harcourt Publishing Company 16