1 / 25

Understanding Heat Transfer, Conduction, Convection and Radiation

Understanding Heat Transfer, Conduction, Convection and Radiation. Heat Transfer. Heat always moves from a warmer place to a cooler place. Hot objects in a cooler room will cool to room temperature. Cold objects in a warmer room will heat up to room temperature. Question.

spencer
Download Presentation

Understanding Heat Transfer, Conduction, Convection and Radiation

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Understanding Heat Transfer, Conduction, Convection and Radiation

  2. Heat Transfer Heat always moves from a warmer place to a cooler place. Hot objects in a cooler room will cool to room temperature. Cold objects in a warmer room will heat up to room temperature.

  3. Question If a cup of coffee and a red popsickle were left on the table in this room what would happen to them? Why? The cup of coffee will cool until it reaches room temperature. The popsickle will melt and then the liquid will warm to room temperature.

  4. Heat Transfer • Heat transfer- movement of heat from a hotter object to a cooler object • Ex: touching a hot pan on the stove- the heat moves from the pan to your hand

  5. Heat Transfer Methods • Heat transfers in three ways: • Conduction • Convection • Radiation

  6. Amethod of heat transfer How does heat energy get from the Sun to the Earth? There are no particles between the Sun and the Earth so it CANNOT travel by conduction or by convection. RADIATION ?

  7. Radiation • Transfer of energy through space • No direct contact • Ex: sunlight, heat from a fire • Energy moves across space in invisible rays

  8. Conduction • Heat transfer b/w touching objects • ex: heat transfer from a hot pot of water to the spoon then to your hand • Feet on hot sand

  9. Convection • Heat transferred by the movement of currents within a fluid • Density- the measure of how much mass there is in a volume of a substance • Ex: rock is more dense than water b/c a given volume of rock has more mass than the same volume of water

  10. Convection What happens to the particles in a liquid or a gas when you heat them? The particles spread out and become less dense. This effects fluid movement. What is a fluid? A liquid or gas.

  11. Fluid movement Cooler, more d____, fluids sink through w_____, less dense fluids. ense armer In effect, warmer liquids and gases r___ up. ise Cooler liquids and gases s___. ink

  12. Convection Currents Water in a pot- as it is being heated the water at the bottom of the pot gets hot, then expands- becoming less dense The warm less dense water moves upward and floats over the cooler, denser water. Then at the surface the warm water cools becoming denser again and so it is pushed back down to the bottom of the pot getting heated again…. This becomes a constant flow- Known as convection currents- the flow which transfers heat within a fluid- Convection currents continue as long as heat is added

  13. Water movement Cools at the surface Convection current Hot water rises Cooler water sinks

  14. Cold air sinks Where is the freezer compartment put in a fridge? Freezer compartment It is warmer at the bottom, so this warmer air rises and a convection current is set up. It is put at the top, because cool air sinks, so it cools the food on the way down.

  15. Conduction, Radiation, or Convection In the evening, snow falls on a cement sidewalk and on a black top playground. Which surface will melt the snow faster and why?

  16. Answer Conduction: The playground because it is black and absorbs more heat; the cement is white and reflects the heat.

  17. Two identical cups of hot cocoa are sitting on a table. One has a metal spoon in it and one does not. After five minutes, which cup is cooler?

  18. Answer Conduction: The cocoa with the spoon in it b/c heat transferred from the cocoa to the cooler spoon

  19. On a hot summer’s day should you close your blinds or leave them open to keep the house cooler?

  20. Answer Radiation: Close your blinds b/c the windows are clear and the infrared rays will go right through the windows and warm your house.

  21. Although you do not touch the flames, your chest feels warm sitting next to an open fire.

  22. Answer Radiation: The fire radiates heat to your chest

  23. A pot of water boils on a hot stove

  24. Answer Convection currents: Pushes the hottest water to the top

  25. Convection Currents in the Earth Heat from the core and mantle cause convection currents in the mantle. Convection currents move inside the Earth’s mantle and outer core. Earth’s mantle is like the water in the pot…. Earth’s core is the heat source

More Related