A certain star's power output is 2.9 x 1026 W. Assuming an ideal radiator with e = 1, calculate its radius in km if its temperature is 5,720 K. The Stefan-Boltzmann constant is 5.67 x 10-8 W/(m².K4).

Derive a relation for Joule – Thomson coefficient for a gas whose equation of state is a P+ V = RT

Vega is the fifth brightest star in the night sky.This bluish dwarf star has a radius of 0.810 x 109 m. If the surface temperature is 9.71 *103 K, what is the rate at which energy is radiated from the star?Assume that the spherical surface behaves as a blackbody radiator.[Surface Area of a sphere = 4πr24πr2 ; Area of a circle = πr2πr2  or πd24πd24 ;σ=5.67⋅10−8Jsm2K4σ=5.67⋅10-8Jsm2K4 ]

3. The classical partition function of a gas of noninteracting indistinguishable particles is written as exp{- N! 2m Z= where N is the number of particles of mass m, r, and p, are the position and the momentum of the ith particle, B = 1/(kpT), and Tis the temperature of the gas. The volume of the gas is V. (a) Find the analytic expression of the partition function of the gas. (b) Obtain the total mean energy E of the gas from the partition function. (c) Obtain the entropy S of the gas from the partition function and the total mean energy. Lexp(-x³xdx = Va Hint: