PROBLEM SET 6 Physics 2022 1. At one stage during its birth, the protosun had a luminosity of 1000 L ʘ and a surface temperature of about 1000 K. What was its radius (use present-day solar radii)? 2. Use the Sun’s luminosity to calculate the mass of H it converts into He during one second. 3. Use the value of the Sun’s luminosity to calculate what mass of hydrogen the Sun will convert into helium during its entire main-sequence lifetime of 1.2 x 10 10 years. (Assume that the Sun’s luminosity remains nearly constant during the entire 1.2 x 10 10 years.) What fraction does this represent of the total mass of hydrogen that was originally in the Sun? 4. Calculate how much energy would be released if each of the following masses were converted entirely into their equivalent energy: (a) a carbon atom with a mass of 2 x 10-26 kg, (b) 1 kg, and (c) a planet as massive as the Earth (6 x 10 24 kg). 5.
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