1. Conversations with the Earth Tom Burbine tburbine@framingham.edu
12/4/2018
Conversations with the Earth Tom Burbine

4. Absorption lines

5. Energy Source for Sun Fusing hydrogen into helium
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Energy Source for Sun
Fusing hydrogen into helium
Hydrogen nucleus – 1 proton
Helium nucleus – 2 protons, 2 neutrons
Need high temperatures for this to occur
~10 million degrees Kelvin or higher

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9. How does Fusion Convert Mass to Energy
12/4/2018
How does Fusion Convert Mass to Energy
What is the most famous formula in the world?

10. E = mc2 m is mass in kilograms c is speed of light in meters/s
12/4/2018
E = mc2
m is mass in kilograms
c is speed of light in meters/s
E (energy) is in joules
very small amounts of mass may be converted into a very large amount of energy

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Who came up with it?

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13. Law Law of Conservation of mass and energy
Sum of all mass and energy (converted into the same units) must always remain constant during any physical process

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15. For example:
1 kg of Hydrogen is fused
0.993 kg of Helium is created
0.007 kg is turned into energy

16. Exercise #7 Let’s calculate the lifetime of the Sun
Need to calculate the rate that the Sun will use up its nuclear fuel

17. Question #1
What formula will you use to calculate how much energy can be generated by the Sun?

18. Question #2
Will all the mass of the Sun be fused into Helium?

19. Question #3 The mass of the Sun is 2 x 1030 kilograms.
Only 10% of the Sun is hot enough to fuse into Helium
What mass of the Sun can be fused into Helium for energy?

20. Question #4 Will all this mass be turned into energy?
If not, what percentage will be turned into energy?

21. Question #5
How much energy will then be produced by the Sun over its lifetime?

22. Question #6 What is the lifetime of the Sun?
We need to know the rate that the Sun gives off energy. Sun gives off 3.8 x 1026 Watts (3.8 x 1026 Joules/second)
Divide the energy produced by the Sun by the rate the Sun gives off energy to determine the lifetime of the Sun

23. Question #7
You get an answer in seconds
How many years is that?

24. Question #8
How many years does the Sun have left?

25. Any Questions?