(a) A low mass star like the sun might have a central density of 189 g/cm 3 and
ID: 1998493 • Letter: #
Question
(a) A low mass star like the sun might have a central density of 189 g/cm3 and be 80.0% 1H and 20.0% 4He. What is the number of mol/cm3 for the 1H, the 4He, and the total number of nucleons plus electrons?
1H = ______ mol/cm3
4He = ______ mol/cm3
Total = _______ mol/cm3
(b) Suppose the same star has a central temperature of T = 15.70 million K. Find the gas pressure and radiation pressure at the center of the star
Pg = ______ N/m2
Pr = ______ N/m2
(c) What percent of the star's central pressure comes from radiation?
_________ %
Explanation / Answer
a) H = 189*0.80 g/cm^3 = 151.2 g/cm^3
= 151.2 mol/cm^3
He = 189*0.20 g/cm^3 = 37.8 g/cm^3
= 9.95 mol/cm^3
total = 161.15 mol/cm^3
b) by ideal gas law,
pv = nRT
Pg = 161.15*8.3*15.7e6/1e-6
= 2.1*10^16 N/m^2
Pr = 1/3 aT^4
= 1/3*0.1e-6*(15.7e6)^4
= 2.025*10^21 N/m^2
c) percentage = 100*2.1e16/2.025e21
= 0.001037 %
=
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.