Energy and Human Ambitions on a Finite Planet, 2021a

C Selected Answers 385
Chapter 5
1. Several inches
2. About the length of a typical room
3. A few kJ total, most in sliding
4. You’ve got this
6. Nearly 1 GJ
7. Two of the points in Example 5.2.1 offer
guidance
8. Figure 5.1 offers hints
9. Roughly half human metabolic power
10. Less than 5 seconds
12. Between 50–100 kcal (200–400 kJ)
13. Sensibly, a little less than 2 minutes
14. Results should be roughly consistent with
Figure 5.2
15. A bit less than 10% of household electricity
16. They’re actually close, within 10%
17. More than two
18. Several kWh; less than $1
19. On the low end of the human metabolism
range; the equivalent cost of 10–20 burritos
20. A few hundred W
21. Comparable to running a clothes dryer
(Fig. 5.2)
22. Several hundred MJ
23. Over 100 kWh; 2–4 burritos-worth
24. Several Therms; cost of fast-food lunch
25. Several gallons; cost of fast-food lunch for
two
26. One is about twice the other
27. A little in excess of 10 kW
28. Less than a quarter of estimated
29. Between 1 <strong>and</strong> 2 hours per day
30. The largest number is near 10 8
31. Six of the entries are inverses of six others
32. A little over an Amp
33. Nearly 10 kW; will cost over $1,000; don’t
do this!
34. Will last 2–3 hours
35. In line with most chemical reactions, in
the 50–200 kJ/mol range
36. Between 3–5×10 −19 J per photon; get more
than 10 18 /sec
37. In the neighborhood of 1 μmor1eV
Chapter 6
1. Approx. 200 kJ, depending on mass
2. Several minutes
3. Several minutes
4. About 5 minutes
5. A few hours
6. Not below freezing
7. Not quite up to “room” temperature
8. Not quite half the time
9. The cost of two burritos per day
10. Instances of heat/flame causing movement
11. See Table 6.2
12. Roughly 30 kJ <strong>and</strong> 100 J/K
13. Between 5–10%
14. A couple dozen percent, roughly
15. Pushing 100%, but not quite there
16. Achieves about 1/3 of theoretical
17. ΔT > 50 ◦ C; environment not that cold
18. Close to a dozen kJ
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