[填空题]
Energy reaches Earth fr f*:- d;qfi*bhg-vzg,t* llvqolvsku ) 2vb)e2m the Sun at a rate of about $1400\ \text{W/m}^2$. Calculate
(a) the total power output of the Sun,$\approx $ $ \times 10^{26}\ \text{W}$
(b) the number of protons consumed per second in the reaction of Eq.31- 7, assuming that this is the source of all the Sun's energy. $\approx $ $ \times 10^8\ \text{protons/s}$
(c) Assuming that the Sun's mass of $2 \times 10^{30}\ \text{kg}$ was originally all protons and that all could be involved in nuclear reactions in the Sun's core, how long would you expect the Sun to "glow" at its present rate? See previous Problem.$ \approx $ $ \times 10^{11}\ \text{yr}$
