Question

Problem 1: The core of the Sun has a temperature of 1.5 × 10⁷ K, while the surface of the Sun has a temperature of 4910 K (which varies over the surface, with the sunspots being cooler). Treat the core of the Sun and the surface of the Sun as two large reservoirs connected by the solar interior. Nuclear fusion processes in the core produce 3.8 × 10²⁶ J every second. Assume that 100% of this energy is transferred from the core to the surface.

33% Part (a) Calculate the change in the entropy ΔS, in joules per kelvin, of the Sun every second.
33% Part (b) Rigel is a blue giant star with a core temperature of 5.0 x 10⁷ K and a surface temperature of 11500 K. If the core of Rigel produces 60,000 times as much energy per second as the core of the Sun does, calculate the change in the entropy ΔS_R, in joules per kelvin, of Rigel every second.
  33% Part (c) Barnard’s Star is a red dwarf star with a core temperature of 7.0 x 10⁶ K and a surface temperature of 3930 K. If the core of Barnard’s Star produces 5% as much energy per second as the core of the Sun does, calculate the change in the entropy ΔS_B, in joules per kelvin, of Barnard’s Star every second.

Answer 1