Chapter 1: Problem 24
Verify the total solar power output of \(4 \times 10^{26} \mathrm{~W}\) based on its surface temperature of \(5,800 \mathrm{~K}\) and radius of \(7 \times 10^{8} \mathrm{~m}\), using Eq. \(1.9 .\)
Chapter 1: Problem 24
Verify the total solar power output of \(4 \times 10^{26} \mathrm{~W}\) based on its surface temperature of \(5,800 \mathrm{~K}\) and radius of \(7 \times 10^{8} \mathrm{~m}\), using Eq. \(1.9 .\)
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Get started for freeYour skin temperature is about \(308 \mathrm{~K}\), and the walls in a typical room are about \(295 \mathrm{~K}\). If you have about \(1 \mathrm{~m}^{2}\) of outward-facing surface area, how much power do you radiate as infrared radiation, in Watts? Compare this to the typical metabolic rate of \(100 \mathrm{~W}\).
In the spirit of outlandish extrapolations, if we carry forward a \(2.3 \%\) growth rate \((10 \times\) per century \()\), how long would it take to go from our current \(18 \mathrm{TW}\left(18 \times 10^{12} \mathrm{~W}\right)\) consumption to annihilating an entire earth-mass planet every year, converting its mass into pure energy using \(E=m c^{2} ?\) Things to know: Earth's mass is \(6 \times 10^{24} \mathrm{~kg} ; c=3 \times 10^{8} \mathrm{~m} / \mathrm{s} ;\) the result is in Joules, and one Watt is one Joule per second.
Using Eq. \(1.5\) and showing work, what annual growth rate, in percent, leads to the mathematically convenient factor-of-ten growth every century?
A one-liter jar would hold about \(10^{16}\) bacteria. Based on the number of doubling times in our 24 -hour experiment, show by calculation that our setup was woefully unrealistic: that even if we started with a single bacterium, we would have far more than \(10^{16}\) bacteria after 24 hours if doubling every 10 minutes.
A more dramatic, if entirely unrealistic, version of the bacteria-jar story is having the population double every minute. Again, we start the jar with the right amount of bacteria so that the jar will be full 24 hours later, at midnight. At what time is the jar half full now?
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