Unit 3 Lesson 2 Energy Transfer Copyright Houghton

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

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

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

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

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

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 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

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

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

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

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

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

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

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

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

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

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