Presentation Transcript

1. Heat Flow

   Text book Physical science blue text
2. Sit down at the table that matches your color.
3. Label the top of a page in your notebook: BELL WORK (1/14) Sally’s mother was about to drink a cup of hot tea. She noticed that the tea was too hot to drink. Sally put an ice cube in her mother’s tea so that it would be cool enough to drink. Sally and her family each had different ideas about why the tea cooled off after adding an ice cube. This is what each one said: Sally: I think the cold from the ice cube transferred to the hot tea, and this is what cooled it off Sally’s mom: I think the cold from the ice and the heat energy from the tea moved back and forth until the tea cooled off. Sam: I think it cooled the tea because heat energy from the hot tea transferred to the cold ice cube. Sally’s Dad: I don’t think the ice cube made any difference. It was the air that cooled it off.
4. Bell Work
5. Bell Work
6. RULES AND PROCEDURES Peace or else….. Be in class when the bell ring Get notes when absent Check the science website PPT, assignments, homework Study Island If you need help, ask!!! Signed Lab Sheets ? Everyone?
7. Label the top of a page in your notebook: BELL WORK (1/14) Sally’s mother was about to drink a cup of hot tea. She noticed that the tea was too hot to drink. Sally put an ice cube in her mother’s tea so that it would be cool enough to drink. Sally and her family each had different ideas about why the tea cooled off after adding an ice cube. This is what each one said: Sally: I think the cold from the ice cube transferred to the hot tea, and this is what cooled it off Sally’s mom: I think the cold from the ice and the heat energy from the tea moved back and forth until the tea cooled off. Sam: I think it cooled the tea because heat energy from the hot tea transferred to the cold ice cube. Sally’s Dad: I don’t think the ice cube made any difference. It was the air that cooled it off.
8. What do you know? What determines the temperature of an object? How is thermal energy different from temperature? What is heat ? How is heat transferred?
9. Temperature Measures how hot or cold something is compared to a reference point Measure the average kinetic energy of the particles in an object. Use Fahrenheit, Celsius, Kelvin Scales to measure temperature
10. Temperature Fahrenheit Used in the USA 32 water freezes, 212 water boils Celsius Used in most of the world 0 water freezes, 100 water boils Kelvin Used by scientists Uses same units as Celsius 273.15 water freezes, 373.15 water boils Based on absolute zero Where all kinetic energy stops
11. Measure Hot and Cold Measure the Average kinetic energy of particles in an object Temperature Kelvin Fahrenheit Celsius -USA -32 F ice -212 F Boiling water -Scientists use -273.15 K ice -373 K boiling water -most of world -0 C ice -100 C boiling water
12. Temperature Scales Kelvin -Used by Scientific community 273.15 K H20 Freezes 373.15 K H20 Boils Based on absolute zero 0 K All kinetic energy stops Fahrenheit Used in the USA 32 F H20 freezes 212 F H20 boils Celsius Used in most of the world 0 C H20 freezes 100 C H2 0 boils same units as Kelvin
13. Temperature
14. Thermal Energy vs. Temperature Temperature Measure average kinetic energy of the particles in an object How fast or slow particles are moving Thermal Energy Measure the TOTAL ENERGY of all particles in an object Depends on temperature, number of particles and how particles are arranged Thermal Energy changes with change of states
15. Measures total energy of particles in an object (kinetic + potential) Thermal Energy Depends on: 1)temperature 2)# of particles 3)how particles are arranged Changesas the“state of matter” changes ( freezing, melting, boiling)
16. Heat The transfer of thermal energy from a warmer object to a cooler object Only moves in one direction Measured in Joules (unit of energy) Miami basketball team
17. How is Heat transferred? Conduction Transfer heat from one particle to another Convection Transfer of thermal energy by movement of warmer and cooler fluids (air, water, etc) from place to place Radiation Transfer heat by EM waves
18. Conduction Heat is transferred from one particle to another within an object or between two objects thru collisions Fast moving particles collide with slow moving particles Collisions cause slow moving particles to move faster Faster moving particles = temp increase
19. Convection Transfer of thermal energy by movement of particles from one part of the material to another Occurs in fluids (can be liquids and gasses) Heated air is less dense and rises Cold air is more dense and falls Creates a circular motion called a Convection Current Convection Currents in air cause wind and weather changes
20. Radiation Transfer of energy by EM waves Only form of Heat that doesn’t require matter Exp Feel the heat radiate from a fire without touching the flames The sun’s radiant energy travels to the earth through space (150 million miles)
21. Thermal Energy Transfer Thermal Expansion Amt of thermal energy increases Causes the volume of the material to increase Contraction Amt of thermal energy decreases Causes the volume of the material to decrease
22. Specific Heat The amount of thermal energy required per unit of mass to increase the temperature of a material by one degree. Low specific heat Transferring small amount of energy increases its temperature significantly Hi specific heat Takes more energy to increase temperature
23. Thermal Energy in the Home Thermal energy transformed into other types of energy Heat appliances, coffee makers transform electric into thermal energy Thermostat regulates the temperature of a system Bi metallic coil inside tightens and loosens, causing a switch to turn on and off Refridgerator keeps food cold by removing thermal energy from inside the fridge and releasing it to the surroundings
24. Heat Engines A machine that converts thermal energy into mechanical energy Care engine Chemical energy-thermal energy-mechanical energy Not efficient about 20% of chemical energy of gasoline turns into mechanical energy Rest of the energy heats the car engine
25. What do you know? What determines the temperature of an object? How is thermal energy different from temperature? What is heat? How is heat transferred?