HEAT

1. HEAT

2. What is heat? • Heat is a form of energy. • Other types of energy that we learn about are sound and light.

3. What you will learn (the Utah State curriculum) • Standard 6 Students will understand properties of heat, light, and sound. • Objective 1: Investigate the movement of heat between objects by conduction, convection, and radiation.

4. What you will learn (the Utah State curriculum) continued… • Compare materials that conduct heat to materials that insulate the transfer of heat energy. • Describe the movement of heat from warmer objects to cooler objects by conduction and convection. • Describe the movement of heat across space from the sun to Earth by radiation. • Observe and describe, with the use of models, heat energy being transferred through a fluid medium (liquid and/or gas) by convection currents. • Design and conduct an investigation on the movement of heat energy.

5. Heat on the move • Heat always travels from hotter objects to cooler objects. • Molecules in cooler objects are closer together. • Ice in water melts because the energy is moving from the water to the ice. • How do molecules move as objects become warmer?

6. Natural Heat Sources • Please list (in your notebook) all the sources of natural heat you can think of (for example: sun).

7. Natural Heat Sources • Sun • Fire • Body heat • Lightning • Lava and volcanoes • Geothermal energy (geysers, hot springs) • Friction

8. Other Heat Sources • Heater / Furnace • Electric blanket. • Microwave oven. • Stove • Lamps / Light Bulbs • Engine

9. VOCABULARY • Conduction • Conductor • Insulator • Radiation • Convection

10. Types of Heat Transfer • Conduction • Convection • Radiation

11. Conduction • Heat transfer by objects touching • Examples: egg cooking on a frying pan, butter on corn cob

12. Conduction • Particles move faster, there is more energy, temperature is higher • Fast moving particles hit slower moving particles and energy is transferred to them until they are all moving at the same speed • Ear demonstration • Did the energy go from your hands to your ears or your ears to your hands?

13. Conductors • A substance that allows heat, electricity, or sound to travel through it Examples are: • Metal (best) • Aluminum foil • Glass (not electricity)

14. Conductors • Please write at least two examples of conductors in your notes. • You may NOT use the ones we have discussed in class.

15. Insulators • are substances that do not allow heat or sound to travel through easily Examples are: • Wood • Plastic • Rubber • Gases and liquids • Styrofoam • Snow • Earth (dirt) • Fiberglass

16. Insulators • Why do pans have plastic or wood handles? • How does a thermos work? • Write two other examples of insulators in your notes.

17. Convection • Heat transfer through liquids and gasses as currents • Heat always rises • Examples: Hot air balloon, clothes dryer, water boiling, room warming up when heater goes on, soaring bird • Draw in your notebook.

18. Convection • This is the movement that transfers heat • Causes warm substances to rise and cool ones to sink (p. 173) • As substances warm, the particles move apart and it becomes lighter • The lighter substance rises while the heavier one moves down • Can you think of any examples of convection?

19. Radiation • Heat transfer through space in the form of electromagnetic waves • All warm objects radiate (give off) heat waves • Does NOT require matter or a medium for transfer (that’s why we still feel the Sun’s heat) • Examples: Sun heating the Earth, heat surrounding a fire, heat given off by electric heater, heat near a hot oven, heat lamps in fast food restaurants

20. How does heat travel? • Is it from cooler objects to warmer objects? or is it… • Is it from warmer objects to cooler objects?

21. Molecules & Heat • As objects get hotter, the molecules move faster and farther apart. • As objects get colder, the molecules move slower and closer together.

22. Testing your heat knowledge Write down what kind of heat each of these examples is: • Pancakes cooking on a griddle • Vegetables boiling in a pan • Roasting a marshmallow by a fire

23. And the answers are: • Pancakes cooking on a griddle • Vegetables boiling in a pan • Roasting a marshmallow over a fire • Conduction • Convection • Radiation

24. More Heat Questions Questions: • Which has more heat: a lighted match or an ice sculpture? • Why does one have more?

25. And the answers… Answers: • An ice sculpture • An ice sculpture because it is bigger. • More molecules=more heat energy

26. Round 3: Questions: • Which would cook faster: brownies in a metal pan or in a glass pan? • Why?

27. Round 3 Answers • Answers: • Brownies in a glass pan. • Glass is transparent (see through) so the brownies can cook through radiation & conduction. Metal reflects the heat by radiation so the brownies cook only by conduction.

28. Measurement of Heat • Measuring the amount of kinetic energy each of the individual particles has in an object. • The tool we use to measure heat is a thermometer. Units • Joules • Calories • Temperature (Celsius, Fahrenheit, or Kelvin)

29. Fahrenheit (F) & Celsius (C) • Water boils at ____ degrees F & _____ degrees C (at sea level). • Water freezes at ____ degrees F & _____ degrees C (at sea level).

30. More (F) & (C) • Room temperature is ______ degrees F & ______ degrees C. • Normal body temperature is _______ degrees F & ______ degrees C. • Which is hotter: 100 degrees F or 100 degrees C?

31. More (F) & (C) • A hot day is about 38 degrees C & 100 degrees F. • Anything below 15 degrees C or 65 degrees F and you’ll probably want a jacket.

32. Kelvin • This scale is used in science a lot. • Water freezes (at sea level) at 273 degrees K. • Water boils (at sea level) at 373 degrees K. • The lowest possible temperature is 0 K (Zero Kelvins).

33. Thermal Energy • The total energy of all the particles in a substance or material is called thermal energy. • Cocoa example (p. 170) • Big cocoa pot vs. little mug

34. Household Heat • How is heat transferred through objects in every day life? • You need at least 10 objects/situations where heat is transferred. You need to decide which type of heat is used to transfer heat and make a chart. (I.e. laying on the sidewalk to get warm after running through sprinklers would be conduction)

35. Save the Life of an Ice Cube • Each student will design an experiment by him/herself. • The purpose of this experiment is to prolong the life of an ice cube. • This experiment must include all of the first four steps in the scientific process.

36. More about the experiment • Purpose • Research • Hypothesis (must be testable) • Experiment • Analysis (we won’t be doing this step) • Conclusion (we won’t be doing this)

37. Experiment Guidelines • The students may use materials from home, however the final project may NOT include something someone else has made (I.e. any part of a Thermos). • No batteries, electricity, chemicals, etc may be used.

38. More about it • No cold substance may be used. (I.e. cannot put cold water or a frozen ice pack in it). • Students must be able to explain how the project insulates heat. • Project must be testable.

39. Even more about it • You will NOT actually make the project. You will ONLY plan and design it. • Due Tuesday, September 30. • Please use the correct form.