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Q7 1
kg of H fused into He. How much
energy is
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liberated? Use E = mc2, but must
determine how
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much
mass is converted. We learned in
class that
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4.3 10-12 J released for each He
produced. He
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masses
6.645 10-27 kg, so we have 1.5x1026 He
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in a
kg, each producing the above energy.
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Multiply
the energy per He times number of He =
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1.5x1026 x 4.3 10-12 J = 6.4x1014
J
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Q9 Sunspot brightness, use E = σT4
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(T1/T2)4 = (5800/4200)4 = 3.6 times
brighter
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