Conversations with the Earth Tom Burbine [e-mail]

1
Conversations with the EarthTom
Burbinetburbine_at_framingham.edu
2
Energy

• Energy is the property of a system that enables
  it to do work

3
(No Transcript)
4
Work

• Work Force x Distance

5
To do work

• You need to move something

6
Energy units

• In English Units, we use calories to measure
  energy
• In science (and in this class), we will use
  joules to measure energy
• 1 Joule 1 kgm2/s2

7
Joule

• One joule is defined as the amount of work done
  by a force of one Newton moving an object through
  a distance of one meter

8
(No Transcript)
9
Thermal energy (kind of kinetic energy)?

• Temperature is a measure of the average kinetic
  energy of the particles
• Higher temperature more kinetic energy,
  particles moving faster
• For examples, air molecules around you are moving
  at 600 m/s

http//eo.ucar.edu/webweather/molecules.html
10
Temperature scales

• In America, we use Fahrenheit
• Water freezes at 32 degrees F
• Water boils at 212 degrees F
• Everywhere else, they use Celsius
• Water freezes at 0 degrees C
• Water boils at 100 degrees C

11
In Science

• Temperature is usually given as Kelvin
• Zero Kelvin is absolute zero nothing moves
• Add 273.15 to the Celsius temperature to get the
  Kelvin temperature
• 273.15 Kelvin 0 degrees Celsius

12
(No Transcript)
13
(No Transcript)
14
Absolute Zero

• 0 Kelvin
• Lowest limit of temperature
• Molecules have lost all available kinetic energy

15
Power

• Power work/time
• Units of power are watts Joules/second

16

• Flux is the amount of energy (or the number of
  photons) that passes perpendicularly through a
  unit surface area per unit time
• Flux is measured in Joules/(second-meter2)
• Watts/m2

17
Blackbody

• A black body is an object that absorbs all
  electromagnetic radiation that falls onto it.
• Perfect emitter of radiation
• Radiates energy at every wavelength

18
http//www.astro.ncu.edu.tw/contents/faculty/wp_ch
en/Ast101/blackbody_curves.jpg
19
http//www.rap.ucar.edu/general/asap-2005/Thur-AM2
/Williams_DoD_Satellites_files/slide0005_image020.
gif
20
Stefan-Boltzman Law

• Flux sT4
• Temperature in Kelvin
• s 5.7 x 10-8 Watt/(m2?K4)
• For example, if the temperature of an object is
  10,000 K
• Flux 5.7 x 10-8 x (10,000)4
• Flux 5.7 x 10-8 x (1 x 1016)
• Flux 5.7 x 108 W/m2

21
Wiens Law

• Wavelength of Maximum intensity of the blackbody
  curve peak 2.898 x 10-3 m K
• T (K)
• T 10,000 K
• ?max (2.898 x 10-3 /10,000 ) m
• ?max 2.0 x 10-7 meters

22
(No Transcript)
23

• An Astronomical Unit (AU) is the average
  distance of the Sun to the Earth

24
Inverse Square Law

• The solar flux varies inversely by the square of
  the distance (1/d2)
• If the Earth was moved to 10 Astronomical Units
  away, the flux from the Sun would be 1/100 times
  smaller
• If the Earth was moved to 100 Astronomical Units
  away, the flux from the Sun would be 1/10000
  times smaller

25

• If the Earth was moved to 1 x 108 Astronomical
  Units away, the Sun would be
• A) 1 x 10-12 times dimmer
• B) 1 x 10-14 times dimmer
• C) 1 x 10-16 times dimmer
• D) 1 x 10-18 times dimmer
• E) 1 x 10-20 times dimmer

26

• If the Earth was moved to 1 x 108 Astronomical
  Units away, the Sun would be
• A) 1 x 10-12 times dimmer
• B) 1 x 10-14 times dimmer
• C) 1 x 10-16 times dimmer
• D) 1 x 10-18 times dimmer
• E) 1 x 10-20 times dimmer

27
(No Transcript)
28
(No Transcript)
29
Solar flux

• Solar flux at the Earths orbit is 1366 W/m2
• If you move the Earth to 2 AU
• Flux 1366 W/m2 (1 AU)2
• (2 AU)2
• Flux 1366 W/m2 341.5 W/m2
• 4

30

• http//www.learner.org/resources/series28.html

31
Any Questions?