PROBLEM 51 & 52 May 28 2010

PROBLEM 51 & 52 May 28 2010 - 4 atom (includes the...

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Solving Problems 51 and 52 Phys 002C May 26 2010 Problem 51 : (Like Problem 30.6) A certain number N of ordinary hydrogen (not deuterium) atoms weighs exactly 4 kg. How much does the same number of He 4 atoms weigh? Note: converting 4 atoms of hydrogen into He 4 releases 28 MeV of energy, and the rest energy of the hydrogen atom is 938 MeV. (a) 2.345 kg; (b) 6.543 kg; (c) 3.970 kg; (d) 3.141 kg; (e) 7.857 kg. What do you know? Four hydrogen atoms have a mass of 4 938 MeV=3.752 GeV. Subtract off the 28 MeV binding energy and you get the mass of a He
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Unformatted text preview: 4 atom (includes the electrons) = 3.724 GeV. The weight of the sample of He 4 would then be 4 kG 3.724/3.752 = 3.970 kg Problem 52 : (Sort of Like Problem 30.12) What dose of radiation in Grays would heat a sample of water 1 o C ? (a) 84 Gy; (b) 119 Gy; (c) 213 Gy; (d) 1 Gy; (e) 4186 Gy. What do you know? One Gray is a dose of 1 J/kg. To heat water 1 O C requires 1 calorie = 4.186 J per gram. So we would need 4,186 Gy to heat 1 kg of water by 1 O C....
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