Energy and Human Ambitions on a Finite Planet, 2021a

C Selected Answers 390
13. Box barely fits north–south in U.S.
14. Personal preferences play a role
Chapter 15
1. A blueberry
2. N 8
3. Use Z 26 to get there
4. Should match quite well
5. Two diagonals have no gray squares
6. One has a half-life longer than a million
years
7. Roughly twice as old as agriculture
8. Between 1–2%
9. One is about 3% of the other (both decay)
10. Step right
11. That last step might take a while
12. Two decays do it
14. S<strong>and</strong> does the job
15. Somewhere between a car <strong>and</strong> a bus?
16. Close to 1 kg
17. Around a couple-dozen micrograms
18. Table should match
19. <strong>Energy</strong> has a mass, via E mc 2
20. Adds about 1% to the mass
21. Not far from 1,500 MeV
22. Not much
23. Figure 15.14 is relevant
24. It’s a strontium isotope
25. A is twice a prime number
26. Stick to 80 < A < 110 <strong>and</strong> 125 < A < 155
to respect distributions
27. Mid-20s of MeV
28. From steam onwards, it’s basically the
same
29. Between 3 <strong>and</strong> 5 cents per kWh
30. A few per week!
31. Around 20 tons per year (more in reality)
32. Almost 2 million tons
33. A few hundred tons
34. Less than a decade
37. Two st<strong>and</strong> out
38. Centuries
39. More often than once every two years
41. A nearly exact match!
42. Worked out in text: no calculation
necessary—just interpretation
43. <strong>Energy</strong> jump size
44. Like a milk jug
Chapter 16
1. Shortfall is more than a factor of 200
2. A bit farther than the record
3. About as thick as a six-story building is
tall
6. Ranges about 55–85%
7. Geothermal is a bit less than 1% of alternative
electricity
8. A little shy of the 8 m design height, sensibly
9. Works out
10. Diameter like a small house’s footprint
11. Comparable to human metabolism; 1% of
American dem<strong>and</strong>
12. A little more than 6 times that in Example
16.4.1
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