heat transfer or heat energy
DESCRIPTION
Heat Transfer or Heat Energy. Learning objective and Outcomes. Objective The objective of this topic is to understand the methods of heat transfer Outcomes At the end of this session, students should be able to: Recognise heat as a form of energy - PowerPoint PPT PresentationTRANSCRIPT
![Page 1: Heat Transfer or Heat Energy](https://reader035.vdocuments.net/reader035/viewer/2022081504/5681342f550346895d9b1fab/html5/thumbnails/1.jpg)
![Page 2: Heat Transfer or Heat Energy](https://reader035.vdocuments.net/reader035/viewer/2022081504/5681342f550346895d9b1fab/html5/thumbnails/2.jpg)
Objective The objective of this topic is to understand the
methods of heat transfer
OutcomesAt the end of this session, students should be
able to: Recognise heat as a form of energy Recognise the three types of energy transfer
(Conduction, Convection and Radiation) Describe convection in liquid or gas Describe the process of heat radiation and that
black is a good radiator
![Page 3: Heat Transfer or Heat Energy](https://reader035.vdocuments.net/reader035/viewer/2022081504/5681342f550346895d9b1fab/html5/thumbnails/3.jpg)
If a cup of hot coffee and an ice cube were left on the table in this room what would happen to them?
The cup of coffee will cool until it reaches room temperature. The ice cube will melt and then the liquid will cool to room temperature.
Why?They both have to adapt the rates at which
the temperature changes in the room
![Page 4: Heat Transfer or Heat Energy](https://reader035.vdocuments.net/reader035/viewer/2022081504/5681342f550346895d9b1fab/html5/thumbnails/4.jpg)
Heat energy only flows when there is a temperature difference from a warmer area to a cooler area.
Heat is a type of energy called thermal energy.
1. Conduction
During heat transfer, thermal energy always moves in the same direction:
HOT COLD
2. Convection3. Radiation
Heat can be transferred (moved) by three main processes:
![Page 5: Heat Transfer or Heat Energy](https://reader035.vdocuments.net/reader035/viewer/2022081504/5681342f550346895d9b1fab/html5/thumbnails/5.jpg)
Conduction
Conduction is the process of heat transfer through a medium or material without any movement of the medium or material
5
![Page 6: Heat Transfer or Heat Energy](https://reader035.vdocuments.net/reader035/viewer/2022081504/5681342f550346895d9b1fab/html5/thumbnails/6.jpg)
As you heat the metal, the particles vibrate, these vibrations make the adjacent particles vibrate, and so on and so on, the vibrations are passed along the metal and so is the heat. We call this?
As you heat the metal, the particles vibrate, these vibrations make the adjacent particles vibrate, and so on and so on, the vibrations are passed along the metal and so is the heat. We call this?
![Page 7: Heat Transfer or Heat Energy](https://reader035.vdocuments.net/reader035/viewer/2022081504/5681342f550346895d9b1fab/html5/thumbnails/7.jpg)
Metal is a conductor, wood is an insulator. The metal conducts the heat away from your hands, the wood does not conduct the heat away from your hands as well as the metal, so the wood feels warmer than the metal.
![Page 8: Heat Transfer or Heat Energy](https://reader035.vdocuments.net/reader035/viewer/2022081504/5681342f550346895d9b1fab/html5/thumbnails/8.jpg)
Some materials conduct heat more rapidly than others
Such materials are called thermal conductors
Most metals are good thermal conductors
8
![Page 9: Heat Transfer or Heat Energy](https://reader035.vdocuments.net/reader035/viewer/2022081504/5681342f550346895d9b1fab/html5/thumbnails/9.jpg)
9
![Page 10: Heat Transfer or Heat Energy](https://reader035.vdocuments.net/reader035/viewer/2022081504/5681342f550346895d9b1fab/html5/thumbnails/10.jpg)
Which is the best conductor?
--> Brass --> Iron --> Water
10
MaterialThermal
conductivity (W/mk)
Brass 106
Iron 84
Water 0.56
Wood 0.13
Air 0.024
Which is the least conductor?
--> Air
![Page 11: Heat Transfer or Heat Energy](https://reader035.vdocuments.net/reader035/viewer/2022081504/5681342f550346895d9b1fab/html5/thumbnails/11.jpg)
Second method of heat transfer
![Page 12: Heat Transfer or Heat Energy](https://reader035.vdocuments.net/reader035/viewer/2022081504/5681342f550346895d9b1fab/html5/thumbnails/12.jpg)
12
Convection is the transfer of heat from one place to another by the movement of currents in liquids or gases
Definition!
![Page 13: Heat Transfer or Heat Energy](https://reader035.vdocuments.net/reader035/viewer/2022081504/5681342f550346895d9b1fab/html5/thumbnails/13.jpg)
![Page 14: Heat Transfer or Heat Energy](https://reader035.vdocuments.net/reader035/viewer/2022081504/5681342f550346895d9b1fab/html5/thumbnails/14.jpg)
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.
![Page 15: Heat Transfer or Heat Energy](https://reader035.vdocuments.net/reader035/viewer/2022081504/5681342f550346895d9b1fab/html5/thumbnails/15.jpg)
Cooler, more d____, fluids sink through w_____, less dense fluids.
In effect warmer liquids and gases r___ up.
Cooler liquids and gases s___.
ensearmer
ise
ink
![Page 16: Heat Transfer or Heat Energy](https://reader035.vdocuments.net/reader035/viewer/2022081504/5681342f550346895d9b1fab/html5/thumbnails/16.jpg)
Hot water rises
Cooler water sinks
Convection current
Cools at the surface
![Page 17: Heat Transfer or Heat Energy](https://reader035.vdocuments.net/reader035/viewer/2022081504/5681342f550346895d9b1fab/html5/thumbnails/17.jpg)
![Page 18: Heat Transfer or Heat Energy](https://reader035.vdocuments.net/reader035/viewer/2022081504/5681342f550346895d9b1fab/html5/thumbnails/18.jpg)
![Page 19: Heat Transfer or Heat Energy](https://reader035.vdocuments.net/reader035/viewer/2022081504/5681342f550346895d9b1fab/html5/thumbnails/19.jpg)
Why is the freezer compartment at the top of a fridge?
Where is the freezer compartment put in a
fridge?
It is put at the top, because cool air sinks, so
it cools the food on the way down.
It is warmer at the bottom, so this warmer air rises and a convection current is set up.
![Page 20: Heat Transfer or Heat Energy](https://reader035.vdocuments.net/reader035/viewer/2022081504/5681342f550346895d9b1fab/html5/thumbnails/20.jpg)
Third method of heat transfer
![Page 21: Heat Transfer or Heat Energy](https://reader035.vdocuments.net/reader035/viewer/2022081504/5681342f550346895d9b1fab/html5/thumbnails/21.jpg)
Radiation is the transfer of heat, in the form of waves, from one place to another without a medium.
21
![Page 22: Heat Transfer or Heat Energy](https://reader035.vdocuments.net/reader035/viewer/2022081504/5681342f550346895d9b1fab/html5/thumbnails/22.jpg)
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
![Page 23: Heat Transfer or Heat Energy](https://reader035.vdocuments.net/reader035/viewer/2022081504/5681342f550346895d9b1fab/html5/thumbnails/23.jpg)
![Page 24: Heat Transfer or Heat Energy](https://reader035.vdocuments.net/reader035/viewer/2022081504/5681342f550346895d9b1fab/html5/thumbnails/24.jpg)
![Page 25: Heat Transfer or Heat Energy](https://reader035.vdocuments.net/reader035/viewer/2022081504/5681342f550346895d9b1fab/html5/thumbnails/25.jpg)
Heat can move by travelling as infrared waves.
This means that infrared waves act like light waves:
They can travel through a vacuum.
They travel at the same speed as light – 300,000,000 m/s.
They can be reflected and absorbed.
Infrared waves heat objects that absorb them and are alsoknown as thermal radiation.
These are electromagnetic waves, like light waves, but with a longer wavelength.
![Page 26: Heat Transfer or Heat Energy](https://reader035.vdocuments.net/reader035/viewer/2022081504/5681342f550346895d9b1fab/html5/thumbnails/26.jpg)
Radiation travels in straight lines
True/False
Radiation can travel through a vacuum
True/False
Radiation requires particles to travel
True/False
Radiation travels at the speed of light
True/False
![Page 27: Heat Transfer or Heat Energy](https://reader035.vdocuments.net/reader035/viewer/2022081504/5681342f550346895d9b1fab/html5/thumbnails/27.jpg)
Four containers were filled with warm water. Which container would have the warmest water after ten minutes?
Shiny metal
Dull metal
Dull black
Shiny black
The __________ container would be the warmest after ten minutes because its shiny surface reflects heat _______ back into the container so less is lost. The ________ container would be the coolest because it is the best at _______ heat radiation.
shiny metalradiation
dull blackemitting
![Page 28: Heat Transfer or Heat Energy](https://reader035.vdocuments.net/reader035/viewer/2022081504/5681342f550346895d9b1fab/html5/thumbnails/28.jpg)
Four containers were placed equidistant from a heater. Which container would have the warmest water after ten minutes?
The __________ container would be the warmest after ten minutes because its surface absorbs heat _______ the best. The _________ container would be the coolest because it is the poorest at __________ heat radiation.
dull blackradiation
shiny metalabsorbing
Shiny metal
Dull metal
Dull black
Shiny black
![Page 29: Heat Transfer or Heat Energy](https://reader035.vdocuments.net/reader035/viewer/2022081504/5681342f550346895d9b1fab/html5/thumbnails/29.jpg)
29
![Page 30: Heat Transfer or Heat Energy](https://reader035.vdocuments.net/reader035/viewer/2022081504/5681342f550346895d9b1fab/html5/thumbnails/30.jpg)
1. Which of the following is not a method of heat transfer?
A. Radiation
B. Insulation
C. Conduction
D. Convection
![Page 31: Heat Transfer or Heat Energy](https://reader035.vdocuments.net/reader035/viewer/2022081504/5681342f550346895d9b1fab/html5/thumbnails/31.jpg)
2. In which of the following are the particles closest together?
A. Solid
B. Liquid
C. Gas
D. Fluid
![Page 32: Heat Transfer or Heat Energy](https://reader035.vdocuments.net/reader035/viewer/2022081504/5681342f550346895d9b1fab/html5/thumbnails/32.jpg)
3. How does heat energy reach the Earth from the Sun?
A. Radiation
B. Conduction
C. Convection
D. Insulation
![Page 33: Heat Transfer or Heat Energy](https://reader035.vdocuments.net/reader035/viewer/2022081504/5681342f550346895d9b1fab/html5/thumbnails/33.jpg)
4. Which is the best surface for reflecting heat radiation?
A. Shiny white
B. Dull white
C. Shiny black
D. Dull black
![Page 34: Heat Transfer or Heat Energy](https://reader035.vdocuments.net/reader035/viewer/2022081504/5681342f550346895d9b1fab/html5/thumbnails/34.jpg)
5. Which is the best surface for absorbing heat radiation?
A. Shiny white
B. Dull white
C. Shiny black
D. Dull black