Page 102 - Schaum's Outline of Theory and Problems of Applied Physics

CHAP. 7] ENERGY 87

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7.7. (a) 3.17 × 10 ft·lb (b) 3.2 hp
7.8. 20 kW

7.9. (a) 1.57 MJ (b) 5h50min (c) 1.57 MJ
7.10. (a) 2400 ft·lb (b) 2000 ft·lb

(c) 400 ft·lb was used in doing work against frictional forces in the pulleys
7.11. 12,250 bulbs

7.12. 92 kN

7.13. From 20 to 30 km/h

7.14. 56.7 ft/s = 38.6 mi/h
7.15. 1.6 × 10 −4 J

7.16. 4.1 × 10 −16 J

7.17. 7.5 m/s
7.18. 0.62 kJ

7.19. 8.8 s

7.20. (a) 1.4 ft/s (b) 8 ft/s

7.21. 50 m

7.22. 3kN
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7.23. 10 lb
7.24. (a) 24 J (b) 9.3 J

7.25. 168 kJ
7.26. 3.7 × 10 −12 kg

7.27. 1.3 × 10 −10 kg

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7.28. (a) 6.05 × 10 J (b) 6.72 × 10 −11 kg