intro to chapter 14, matter very cold, very hot

2. What are these objects?
Order them from coldest to hottest

3. What are these objects?
Order them from coldest to hottest

12. kT is about how
much energy
particles have at
temperature T in
kelvin

13. Worked example
• On a nice summer’s day (27 o
C) how much
energy would the particles have?

14. Worked answer
JkT
KJKkTQ
JKk
KCT o
21
123
123
101.4
3001038.1
1038.1
30027
−
−−
−−
×=
××=≈
×=
==

15. Example questions
• Determine the amount of energy a particle
would have if it were:
– In the centre of the Sun
– In the centre of a supernova
– In Mars’ northern polar cap
– In interstellar space

16. Location k / JK-1
T / K kT / J
Centre of the Sun 1.38 x 10-23
Centre of a supernova 1.38 x 10-23
Within magma 1.38 x 10-23
Within Mars' northern polar
cap
1.38 x 10-23
In interstellar space 1.38 x 10-23

17. Location k / JK-1
T / K kT / J
Centre of the Sun 1.38E-23 1.50E+07 2.07E-16
Centre of a supernova 1.38E-23 1.00E+11 1.38E-12
Within magma 1.38E-23 1.00E+03 1.38E-20
Within Mars' northern polar
cap
1.38E-23 2.30E+02 3.17E-21
In interstellar space 1.38E-23 3.00E+00 4.14E-23

18. If T = 10 000 K
eVkT 1=

19. The eV
• The energy gained by an electron as it moves through a
potential difference of 1 V
JW
VCW
QVW
Q
W
V
19
19
106.1
1106.1
−
−
×=
××=
=
=

20. Show kT = 1eV (T = 10000K)
eVkT
JeV
JkT
KkT
KT
1
106.11
1038.1
100001038.1
10000
19
19
24
≈
×=
×=
××=
=
−
−
−

22. Ideal gas
kT
2
1
kT
2
1
kT
2
3
kT
2
1
kT
2
1
kT
2
1
kT
2
1
kT3

24. Hotter and hotter

25. Life at T = 300 K

26. Fires and kilns, T = 1500 K

27. White hot at the Sun’s surface, T = 6000 K

28. Hotter still: inside the Sun, T = 6000000 K