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Heat

Heat. What is Temperature?. What Do You Think?. What happens when you use a thermometer to measure temperature ?. Temperature Depends on Kinetic Energy. Kinetic Energy is the energy of motion The faster the particles of matter move , the more kinetic energy they have.

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Heat

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  1. Heat

  2. What is Temperature? What Do You Think? What happens when you use a thermometer to measure temperature?

  3. Temperature Depends on Kinetic Energy • Kinetic Energy is the energy of motion • The faster the particles of matter move, the more kinetic energy they have

  4. What is Temperature? Measuring Temperature • Temperature is a measure of the Average Kinetic Energy of a substance • When you measure temperature, you are measuring the average motion of the atoms

  5. What is the difference between temperature and heat? Temperature is a measure of the average kinetic energy of atoms. Thermometersare used to measure temperature This means: the higher the temperature, the faster the atoms move the lower the temperature, the slower the atoms move More Heat Less Heat

  6. What is Temperature? Temperature is expressed by one of 3 scales:

  7. What is Heat? What Do You Think? Which is warmer, the tile or the rug on a bathroom floor?

  8. What is Heat? Heat- A Transfer of Energy • Heat is the transfer of energy between objects or particles that are at different temperatures

  9. Another word for heat is THERMAL ENERGY. This Means: Hot objects contain more thermal energy than cold objects.

  10. What is Heat? Heat- A Transfer of Energy • Energy moves from the warmer object to the cooler object until both are the same temperature. • This is known asThermal Equilibrium

  11. THERMAL EQUILIBRIUM No energy transfer occurs

  12. THERMAL EQUILIBRIUM The point at which two objects reach the same temperature. -Whenever they reach the same temperature, then no more energy transfer is taking place.

  13. What is Heat? Reaching Thermal Equilibrium

  14. THERMAL EQUILIBRIUM No energy transfer occurs

  15. What is Temperature? Thermal Expansion- As temperature rises, volume (size) increases

  16. What is Temperature? Thermal Expansion • When the metal rails in this picture heated up, they increased in length and volume • Thermal Expansion caused the rails to buckle and bend

  17. What is Temperature? Thermal Expansion • The asphalt in the road expands when heated and contracts when cooled • This results in cracks and potholes due to Thermal Expansion

  18. THERMAL EXPANSION The spreading of particles (atoms) or increased volume (size) when an object is heated is known as THERMAL EXPANSION

  19. THERMAL EXPANSION. If energy is added to atoms, they move faster. The faster they move, the further apart they move. This spreading out of atoms happens in solids, liquids and gases. Thermal expansion is why running a tight jar lid under warm water loosens the lid. *pg 154

  20. What is Heat? Energy is Transferred by 3 Methods:

  21. What is Heat? • Conduction is the transfer of thermal energy through direct contact • Hold a metal wire in a flame and energy travels from atom to atom until it burns your hand

  22. CONDUCTION • Transfer of heat from one substance to another by direct contact. • Happens within and between objects that touch each other • Examples: Sauce pan on a stove top, metal spoon in a bowl of soup, ice melting in a warm hand, hot shower, walking on hotcoals

  23. Objects that heat up easily are called CONDUCTORS. Metals are the best conductors Metal objects feel cold because they conduct heat AWAY from your hand Objects that DO NOT heat up easily are called INSULATORS. Things like glass,wood, plastic and rubber are good insulators

  24. Which parts of the pan are conductors and which are insulators?

  25. What is Heat? Convection • Convection is the transfer of thermal energy by the movement of a liquid or a gas • Convection is seen as hot material rises and cool material sinks

  26. CONVECTION • Transfer of heat in liquids and gases ONLY • Heat moves up and down in a circular motion called a CONVECTION CURRENT • Heated liquids and gases are less dense & rise carrying heat with them • Examples: hang gliders, soaring birds, home furnace heating & circulating air

  27. Convection currents cause the Earth’s tectonic plates to move about.

  28. What is Heat? Radiation • Radiation is the transfer of energy through matter or space through light energy, such as visible light and infrared waves • Radiation is the only type of energy transfer where the objects don’t have to touch

  29. RADIATION • transfer of heat through empty space in form of infrared radiation waves (what we think of as heat waves) • Examples: blacktop heats up on a sunny day, hot sand on a beach, electric heaters.

  30. Explain how each of these uses radiant heat.

  31. Web Sites to Visit: Harcourt Science: States of Matter BBC: Science BrainPop: States of Matter Unit A : Chapter 1 : Section 1

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