Question
a) The proton-proton chain efficiently converts hydrogen into helium according to 4H →4 He. A Helium 4 nucleus weighs 6.64638 × 10-27 kg and a Hydrogen nucleus (a proton) weighs 1.67262 × 10-27 kg. Work out the change in mass when 1 kg of Hydrogen is transformed completely into Helium 4. Convert change in mass per kg into energy created, Joules per kg of Hydrogen, using Einstein's formula. E = mc2. (For comparison burning Gasoline releases only ∼ 4.5 × 107 Joules per kg.)
b) The rate that the sun burns in Joules per second is given by the solar luminosity, 4×1026 Watts. State the burning rate in terms of kg of Hydrogen converted per second. The mass of the Sun is 2 × 1030 kg. How long can the sun burn at this speed?