HEAT

1. HEAT

2. HEAT • It is the movement of Thermal Energy from a substance at a higher temperature to another at a lower temperature. • Matter contains thermal Energy……only when this thermal energy is transferred it is called heat.

3. HEAT • When you touch a hot stove, energy enters your hand from the stove because the stove is warmer than your hand.

4. HEAT • If you touch ice, energy transfers from your hand into the cold ice.

5. HEAT • Energy transfer is always from a warmer to a cooler substance. • Heat is transferred by Conduction, convection, and Radiation

6. Conduction: heat is transferred through solids by conduction • Example: A metal spoon being heated in a pot of water being heated on the electric stove. The fast moving particles of the electric coil collide with the slow moving particles of the cool pot. Heat is transferred, making the slow particles move faster. • Then the particles of the pot collide with the particles of water which then collide with the particles of the spoon and the metal spoon becomes hotter.

7. Conductors: A material that allows heat to move through it easily • Good Conductors • Metals: • Copper • Gold • Silver • Iron • Aluminum • Steel • Poor Conductors(Insulators): These do not conduct heat easily • Wood • wool • Paper • Wax • Air • Example: Insulations in the wall of homes, clothes, blankets, fiberglass

8. Convection: Transfer of heat in gases and liquids • When gases and liquids are heated the particles move faster and farther apart and as a result becomes less dense than the cooler surrounding gas or liquid. • The less dense gas or liquid rises and the cooler, denser gas or liquid moves to take its place.

9. Convection: Transfer of heat in gases and liquids • Convection is the movement that transfers heat within the water. • When water at the bottom is heated, its particles move faster and farther apart. As a result the water becomes less dense and moves on top of the more dense water.

10. Convection currents • This flow of water creates a circular motion called convection currents. • Examples: Convection currents are used to transfer heat throughout a building, baseboard heaters • Environment: The air heated by the sun is transferred throughout earth atmosphere by convection currents

11. Radiation: Transfer of Energy by electromagnetic rays. • Examples: Feel the heat near the stove or oven • Radiation from the lamp • Radiation from the sun • Radiation does not require matter to transfer thermal energy

12. Conductors and Insulators • 1.Tile and carpet at the same temperature but the tile feels Cooler because…………….. • Tile is a good conductor and …..it transfers heat away from skin faster than the rug which is an insulator which slows the transfer of heat.

13. Specific Heat • The amount of energy required to raise the temperature of 1 kg of a substance by 1 Kelvin is called Specific Heat. • EX: Sand heats faster than water on a sunny day (At the same temperature) • Unit: Joules per Kilogram-Kelvin (J/Kg.K) • Materials with a high Specific heat can absorb a lot of heat without changing in temperature.

14. Test Yourself: • What is Absolute Zero?

15. What is Absolute Zero? • Coldest Temperature possible • -273 degrees Celsius • No more heat can be removed from it

16. What is Thermal Energy?

17. What is Thermal Energy? • The total energy of all the particles in a substance • The more particles of a substance at given temperature……..the more the thermal energy

18. What is Heat?

19. What is Heat? • The movement of thermal energy from warmer to cooler objects • Heat is transferred by: • __C____________________ • ___C___________________ • ___R___________________ • Radiation is the transfer of energy through…………………………waves.

20. Heat transfers from: • Pick One option: • Cool to warm • Warm to cool • Many directions

21. What are Insulators?

22. What are Insulators? • A material that does not conduct heat well

23. What is Specific Heat? • Give examples of objects with Low and high Specific heat

24. What is Thermal Expansion?

25. What is Temperature?

26. Good Luck