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Slide 1 / 106 Slide 2 / 106 Thermal Energy www.njctl.org Slide 3 / 106 Temperature, Heat and Energy Transfer · Temperature · Thermal Energy Click on the topic to go to that section · Energy Transfer · Specific Heat · Thermodynamics and Energy Conservation Slide 4 / 106 Temperature Return to Table of Contents Slide 5 / 106 Sensing Temperature Which of the following do you think is colder, the ice cream orthe tea? It is easy to tell if an object is hot or cold by touching it. How hot or cold something feels is related to temperature, but only provides a rough indicator. Slide 6 / 106 What is Temperature? To understand temperature, rememberthat all matter is made of molecules that are in constant motion. What kind of energy do they have if they are in motion? Even the molecules in this solid pencil are vibrating relative to a fixed position. The water molecules in this glass are in constant random motion. Slide 7 / 106 Temperature and Kinetic Energy Temperature is directly proportional to the average kinetic energy of an object's molecules. The more kinetic energy molecules have, the higher the temperature. clip: Indiana University Slide 8 / 106 Thermal Expansion As the temperature of a substance increases, its molecules pick up speed and gain kinetic energy. This increase in kinetic energy causes the molecules to spread farther apart and the substance expands. image: National Oceanography Centre Slide 9 / 106 Thermal Contraction As the temperature of a substance decreases, its molecules slow down and lose kinetic energy. What do you think this decrease in kinetic energy causes? Compare it to what we said about warm molecules. Slide 10 / 106 Thermal Expansion Watch this demo of a metal ball and ring to see thermalexpansion. Click here to watch a metal ball and ring demo. Explain what happened to make the ballnot fit. How did the person make the ball fit again? What is happening in terms of the kinetic energy of the molecules in the ball? Slide 11 / 106 Thermal Expansion The change in volume a material experiences due totemperature changes depends on the type of material and the amount of temperature change. Click here to watch what happens when things expand at different rates. Slide 12 / 106 1 All matter consists of molecules that are constantly in motion. True False Slide 12 (Answer) / 106 1 All matter consists of molecules that are constantly in motion. True False True Answer [This object is a pull tab] Slide 13 / 106 2 Temperature is the measure of the average __________ of a substance's molecules. A mass B speed C spacing D kinetic energy Slide 13 (Answer) / 106 2 Temperature is the measure of the average __________ of a substance's molecules. A mass B speed D. kinetic energy C spacing Answer D kinetic energy [This object is a pull tab] Slide 14 / 106 3 After a thunderstorm, the sun comes out and warms a puddle of water that is on the sidewalk. As the puddle of water gets warmer, its molecules: A speed up B slow down C take up less space D gain kinetic energy Slide 14 (Answer) / 106 3 After a thunderstorm, the sun comes out and warms a puddle of water that is on the sidewalk. As the puddle of water gets warmer, its molecules: A speed up B slow down A. speed up C take up less space D. gain kinetic energy Answer D gain kinetic energy [This object is a pull tab] Slide 15 / 106 Measuring Temperature Determining the kinetic energy associated with a substance's molecules would be difficult. Thermometers are used as a more practical way to measure an object's temperature. A thermometer usually consists of a small amount of liquid, such as mercury or colored alcohol, in a narrow tube. Slide 16 / 106 Temperature Scales Three scales of temperature commonly used are: · Fahrenheit: used primarily in the United States · Celsius: 1 degree Celsius= 3.2 degrees Fahrenheit · Kelvin: is based on absolute zero, the lowest temperature something can have. Slide 17 / 106 Temperature Scales Slide 18 / 106 Slide 19 / 106 Slide 20 / 106 Temperature Conversions The lowest temperature an object can have is the lowest value on the Kelvin scale 0 K! One Kelvin is equal to one degree on the Celsius scale. To convert from Celsius to Kelvin use the following equation. K= °C +273 Example: Water boils at 100°C. What is the boiling temperature of water in Kelvin? Click the pot of boiling water for the answer! The answer is 373 K. Just add 273 to 100 °C! Slide 21 / 106 4 The coldest temperature ever recorded was -89.2°C in Antarctica on July 21, 1983. Convert this temperature to °F. Slide 21 (Answer) / 106 4 The coldest temperature ever recorded was -89.2°C in Antarctica on July 21, 1983. Convert this temperature to °F. -128.6 °F 184 K Answer [This object is a pull tab] Slide 22 / 106 5 The coldest temperature ever recorded was -89.2°C in Antarctica on July 21, 1983. Convert this temperature to Kelvin. Slide 22 (Answer) / 106 5 The coldest temperature ever recorded was -89.2°C in Antarctica on July 21, 1983. Convert this temperature to Kelvin. -128.6 °F 184 K Answer [This object is a pull tab] Slide 23 / 106 6 If you measure the temperature of an object, its Kelvin temperature will be larger than its Celsius temperature. A never B always C sometimes D not enough information to determine Slide 23 (Answer) / 106 6 If you measure the temperature of an object, its Kelvin temperature will be larger than its Celsius temperature. A never B always B. always Answer C sometimes D not enough information to determine [This object is a pull tab] Slide 24 / 106 7 The hottest recorded temperature ever recorded was about 329 K in Death Valley, California on July 10, 1913. What is this temperature in Celsius? Slide 24 (Answer) / 106 7 The hottest recorded temperature ever recorded was about 329 K in Death Valley, California on July 10, 1913. What is thisThis temperature is a more challenging in Celsius? question in that it requires students to come up with the "equation" for converting Kelvin to Celsius which is the reverse of converting Celsius to Kelvin. Have a student show their Answer work on the board or explain how they got the answer. [This object56°C is a pull tab] Slide 25 / 106 8 The temperature in deep space is about 3 Kelvin. What is this temperature in °F ? Slide 25 (Answer) / 106 8 The temperature in deep space is about 3 Kelvin. What is this temperature in °F ? about -454 °F Answer [This object is a pull tab] Slide 26 / 106 Thermal Energy Return to Table of Contents Slide 27 / 106 Energy in Matter Molecules in matter possess Kinetic Energy. Do you remember why molecules have kinetic energy? Which drink is likely to have molecules with MORE kinetic energy? How is kinetic energy related to an object's temperature? Slide 28 / 106 9 The hotter an object, the faster the molecules in it move. True False Slide 28 (Answer) / 106 9 The hotter an object, the faster the molecules in it move. True False TRUE Answer [This object is a pull tab] Slide 29 / 106 Energy in Matter Molecules in matter also possessPotential Energy. This energy is based on the attractive forces that all molecules exert on each other. As the molecules move closer together, the potential energy associated with the molecules decreases. As the molecules move farther apart, the potential energy associated with the molecules increases. Slide 30 / 106 10 What two types of energy do molecules in matter possess? A Potential Energy B Kinetic Energy C Gravity D Thermal Energy Slide 30 (Answer) / 106 10 What two types of energy do molecules in matter possess? A Potential Energy B Kinetic Energy A & B C Gravity Answer D Thermal Energy [This object is a pull tab] Slide 31 / 106 11 What type of energy describes the motion of molecules in matter? A Kinetic Energy B Potential Energy Slide 31 (Answer) / 106 11 What type of energy describes the motion of molecules in matter? A Kinetic Energy B Potential Energy Kinetic Energy Answer [This object is a pull tab] Slide 32 / 106 12 Potential energy found in matter is based on the ___________________ between the molecules in matter. A energy B attraction C repulsion D electrons Slide 32 (Answer) / 106 12 Potential energy found in matter is based on the ___________________ between the molecules in matter. A energy B B attraction C repulsion Answer D electrons [This object is a pull tab] Slide 33 / 106 Thermal Energy The TOTAL kinetic and potential energy associated with ALL molecules in a substance is called thermal energy. Kinetic Energy Potential Energy Thermal Energy TOTAL molecular energy Thermal energy and temperature areNOT the same because temperature only considers the average kinetic energy of molecules. Slide 34 / 106 Thermal Energy versus Temperature Both containers of water below are measured to have the same temperature. However, one container of water has MORE thermal energy. It has more water molecules! Which has more thermal energy. Why? Click on the bucket for the answer. Slide 35 / 106 Energy Transfer Return to Table of Contents Slide 36 / 106 Heat and Energy Transfer Heat is the transfer of thermal energy from a higher temperature object or location to a lower temperature object or location. Why does the ice cream feel cold on the tongue?Thermal Click energy for transfersthe answer from the tongue to the ice cream.
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