2 Where Does Heat Come From

Becky McCoy

Title: WHERE DOES HEAT COME FROM? Timing: 50 minutes Target Audience: High school Physics

Objectives: The Students Will Be Able To: • Use a science process and thinking skills. • Accumulate evidence that heat is not an object. • Continue to contrast temperature and heat (thermal energy). • Identify three forms of heat transfer. • Articulate the two types of materials that affect the transfer of thermal energy (insulators and conductors). The Teacher Will Be Able To: • Monitor students’ progress in clarifying misconceptions of heat. • Provide evidence through exploration that heat is not an object or substance. • Reinforce that heat is a thermal transfer process.

Standards Assessed: Advanced Placement (AP) Physics B Competency Goal #31 • Objective 3.02: Evaluate and investigate temperature and heat

Misconception(s) Addressed: • •

“Warm” clothing provides energy to warm up one’s body during cold temperature. Heat is a substance.

Concept Map Vocabulary: • • • • • • •

Heat – Energy transfer from an object/substance with a higher temperature to an object/substance with a lower temperature. Internal Energy – The energy in a system arising from the relative positions and interactions of its parts. Specific Heat – The energy transferred when 1kg of material is raised or lowered 1o Celsius. Heat Transfer – Process by which energy is passed between two different objects/substances. Types of heat transfer include: Radiation, Conduction, Convection, and Diffusion. Radiation – Energy transferred through electromagnetic waves. Conduction – Energy transferred through direct contact of two objects/substances. Convection – the transfer of heat by the circulation or movement of the heated parts of a

Becky McCoy

• • •

liquid or gas. Diffusion – Intermingling of molecular parts due to a change in thermal energy. Insulator – An object or material that minimizes the transfer of thermal energy. Conductor – An object or material that allows thermal energy to transfer easily.

Lesson Plan2 Aim: Provide evidence showing that no object holds a certain amount of heat. Physics Push-Up: (5 min) Students should find their chart paper from last class with their temperature concepts and definitions. Have the following definitions written on the board so students can compare. Students should begin to take notes on the correct definitions. • Temperature – a measure of the average kinetic energy of the individual particles in an object. • Fahrenheit scale – the temperature scale on which 32 and 212 are the temperatures at which water freezes and boils. • Celsius scale – the temperature scale on which zero and 100 are the temperatures at which water freezes and boils. • Kelvin scale – the temperature scale on which zero is the temperature at which no more energy can be removed from matter. • Absolute zero – the temperature at which no more energy can be removed from matter. (0 K) • Thermal energy – the total energy of the particles in an object. • Degree – unit of measurement of temperature. • Calorie – amount of heat required to raise the temperature of one gram of water one degree Celsius; unit used to measure the amount of energy contained within an object or transferred between objects/substances.

Teacher Talk: (5 min) Review definitions of each term from the day before. This is an opportunity for students to finish taking notes on the definitions. Invite a student to come to the front of the room, and hand the student an ice cube to hold (can be put in a sealable bag). Ask the student what is happening. Clarify that the ice is not bringing “cold” to the hand, but that thermal energy is moving from the warm hand to the cold ice cube, until eventually the two objects arrive at the same temperature. The hand’s temperature decreases and the water molecules’ temperature increases. When one’s hand is cold, some people believe that when they put a glove on, it is the glove that provides the heat to warm their hand.

Small Group Activity: Does Winter Apparel Create Heat? (15 min) This activity should be done in pairs. If some students forgot to bring gloves, coats, etc,

Becky McCoy groups of 3-4 can be formed. This activity is best on a sunny day in a room with many windows. Materials: • 2 thermometers per group • Assorted gloves, mittens, coat, etc. for each group • Does Winter Apparel Create Heat Worksheet Procedure: PART I: • Students should predict if the winter apparel would warm up their hands. Will one item work better than another? • Each pair will set the glove or coat in a drawer or other place away from any sunlight and place a thermometer in the inside of each piece of winter apparel, and one thermometer next to each. • After 5 minutes, check the thermometers. The temperatures should both be the same. Students should record their observations. PART II: • Have one student in each pair put the glove or coat on, with a thermometer placed on the inside of the glove/coat, touching the student’s body. The other thermometer should be placed on the counter near the student. • After 5 minutes, record the temperature on each thermometer. PART III: • Now put the thermometer back in the glove or coat only, and let them sit again for five minutes. Record temperature again. • Each student should draw a conclusion on their worksheet. It should read something like: Gloves do not give heat, but will insulate or hold in any heat energy due to your hand. As long as a warm hand is in the glove, the glove will be warm. If the hand is removed, then the glove returns to room temperature. The body gives off heat, and the glove holds the body’s heat close to the skin, keeping the temperature on the skin higher than if the glove were off.

Teacher Talk: Activity Review (10 min) Ask 4 or 5 students for a short summary of their findings. Questions might include the following; • What did you expect to happen in each part of the experiment? • What actually happened? • What can we conclude about winter apparel as a “source of heat”? • Did your findings contradict your hypothesis? • Is there anything about this activity you would have changed? • Are you interested in exploring this further? What are you curious about? • How can we relate our conclusion about this activity to what we know about heat?

Becky McCoy Explain what a good conclusion might sound like. Introduce new vocabulary. • Heat – Energy transfer from an object/substance with a higher temperature to an object/substance with a lower temperature. • Internal Energy – The energy in the system arising from the relative positions and interactions of its parts. • Specific Heat – The energy transferred when 1kg of material is raised or lowered 1o Celsius. • Heat Transfer – Process by which energy is passed between two different objects/substances. Types of heat transfer include: Radiation, Conduction, Convection, and Diffusion. • Radiation – Energy transferred through electromagnetic waves. • Conduction – Energy transferred through direct contact of two objects/substances. • Convection – the transfer of heat by the circulation or movement of the heated parts of a liquid or gas. • Diffusion – Intermingling of molecular parts due to change in thermal energy. • Insulator – An object or material that minimizes the transfer of thermal energy. • Conductor – An object or material that allows thermal energy to transfer easily.

Homework: Hot Homework Worksheet (3 min) Quickly review homework worksheet and relevant instructions.

Exit Strategy: 321 Index Card (2 min) • • • •

3 things they learned in class 2 things they are still confused about 1 Conductor they come in contact with every day 1 Insulator they come in contact with.

Assessment: •

Formative: o Students answers given during Activity Review o 321 Exit cards

References: 1 2

- http://www.ncpublicschools.org/curriculum/science/scos/2004/33apphysicsb - Lesson plan written by Utah LessonPlans and found online at utaheducationnetwork.org

Becky McCoy Name ______________________________________ Date ________

Does Winter Apparel Create Heat??? Hypothesis: Does Winter Apparel Create Heat? What do you expect to observe during this activity? Why?

Will the glove or coat make you warm? Which will be more effective?

Data Measurements:

PART 1 (Glove Away from Heat Source)

Initial Temperature

Time Elapsed

Thermometer in Glove

5:00 min

Control Thermometer

5:00 min

Final Temperature

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PART 2 (Glove On Student)

Initial Temperature

Time Elapsed

Thermometer in Glove

5:00 min

Control Thermometer

5:00 min

PART 3 (Glove On Lab Bench)

Initial Temperature

Time Elapsed

Thermometer in Glove

5:00 min

Control Thermometer

5:00 min

Final Temperature

Final Temperature

Conclusions: What happened? How accurate were your predictions?

What are you curious about? If you were to do this experiment again, what else would you want to discover or explore?

Becky McCoy

HOT HOMEWORK!!!! Name _____________________________Date_________ PART 1 Directions: Determine if the following statements are true or false. Then circle T for TRUE and F for FALSE. T F If something feels hot to your touch, the molecules are moving slower. T F During conduction, heat is transferred from a higher temperature to a lower one. T F Water conducts heat better than a metal spoon. T F A thermos, or other insulator, keeps coffee warm because heat transfers easily through it. T F A vacuum bottle (thermos or insulator) keeps foods either hot OR cold. T F If you heat a pot full of water with a wooden handle, the pot is the insulator and the handle is the conductor. T F A Styrofoam cup is a good insulator. PART 2 Directions: Write in the word or phrase which best completes each of the following statements. You may use the words or phrases once, more than once or not at all. come in contact potential nonmetallic solids

contact insulator vacuum

direct contact insulation good

kinetic metallic solids poor

If something is a poor conductor of heat, it is called a good __________________ . To save on heating bills, it is a good idea to place __________________ between the walls of your house. Conduction occurs because molecules _________________ with each other. When you heat something by conduction, the average _______________ energy of its' molecules increases. Due to a __________________ in between the layers of glass inside the bottle, a thermos bottle can keep liquids hot. Good conduction depends on _________________ between molecules. You would expect a sponge to be a _________________ conductor of heat. Between metallic and non-metallic solids, the best conductors are _______________.