Radiation
Conduction
Convection
Which would you rather be???
(C) Copyright 2014 - all rights reserved www.cpalms.org
Conduction: The transfer of energy from one object to
another object through direct contact (touching).
Example:
A hamburger touching the grill; the burger has a
small amount of energy, and the hot grill has greater
energy.
Energy is transferred to the burger from the
hot grill.
(C) Copyright 2014 - all rights reserved www.cpalms.org
P.S. What happens when you add cheese to the burgers?
Burger
anyone?
The cheese melts
as the burger transfers
energy
into the cheese!
http://upload.wikimedia.org/wikipedia/commons/d/dc/Hamburguesas_grill.jpg
(C) Copyright 2014 - all rights reserved www.cpalms.or
Convection:
The transfer of energy due to the movement of
matter. This happens most efficiently in gases and
liquids.
Convection occurs when hot matter rises and cool
matter sinks due to differences in densities.
(C) Copyright 2014 - all rights reserved www.cpalms.org
Example:
As water is heated in a pot, the
warm water at the bottom starts to rise,
and the cooler water near the top starts to
sink replaceing the rising warm water.
This cycle will continue as you heat the water.
(C) Copyright 2014 - all rights reserved www.cpalms.org
Convection is the transfer of
energy due to the
movement of matter
Watch
video
https://www.youtube.com/watch?v=YbhwXSv9rk4
https://www.google.com/search?as_st=y&tbm=isch&hl=en&as_q=convection&as_epq=&as_oq=&as_eq=&cr=&as_sitesearch=
&safe=images&tbs=sur:fm
(C) Copyright 2014 - all rights reserved www.cpalms.org
Convection video discussion:
1. Why did the red food coloring represent hot
water?
2. Why did the blue food coloring sink to the
bottom?
Answer 1. The hot water molecules move faster and spread the food
coloring faster.
Answer 2. The cold water is denser therefore the molecules move
slowly, spreading the food coloring slower.
(C) Copyright 2014 - all rights reserved www.cpalms.org
Watch the
Conduction & Convection
Video
Bill Nye: Heat
(22 min.)
https://www.youtube.com/watch?v=svqieBM2ijs
(C) Copyright 2014 - all rights reserved www.cpalms.org
Review of notes taken from Bill Nye video
•
•
•
•
•
•
•
•
Heat moves around the Earth 3 ways, conduction, convection,
radiation
Heat is energy, all items have heat
The metal stick will melt the butter faster
More molecules = more heat
Hot water expands and is less dense
Infrared cameras see thermal radiation
Heat radiation is made up of waves
Hot air rises, cold air sinks Heat is transferred by one molecule
bumping into another molecule
(C) Copyright 2014 - all rights reserved www.cpalms.org
Radiation:
The transfer of energy as Electromagnetic Waves.
Radiation can transfer energy between objects
that are not in direct contact (touching).
Other objects besides the Sun can radiate energy
as light and heat.
(C) Copyright 2014 - all rights reserved www.cpalms.org
Examples of Radiation:
1. Microwaves in a microwave oven
2. A blazing fire at the campsite
http://img1.targetimg1.com/wcsstore/TargetSAS//img/p/13/38/13389642.jpg
http://www.clipartbest.com/cliparts/RcA/yzb/RcAyzb6Ri.svg
(C) Copyright 2014 - all rights reserved www.cpalms.org
Radiation Video
Play
http://www.youtube.com/watch?v=nNzDXXUiqRs
(C) Copyright 2014 - all rights reserved www.cpalms.org
Radiation video discussion:
•
•
•
•
•
•
•
Sun & Earth emit electromagnetic radiation
Electromagnetic radiation travels in waves
Short wave lengths carry more energy
Shorter wave lengths = higher temperature
Most of the solar radiation is visible light we see
The Sun emits high energy short wave radiation
The Earth emits low energy long wave radiation
(C) Copyright 2014 - all rights reserved www.cpalms.org
So which would you rather be?
Conduction
Convection
Radiation
(C) Copyright 2014 - all rights reserved www.cpalms.org