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Edition
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SOLUTION
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MANUAL
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Robert A. Ristinen, Jack J. Kraushaar & Jeffrey T. Brack
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Complete Solution Manual for Instructors and
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Students
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© Robert A. Ristinen, Jack J. Kraushaar & Jeffrey T. Brack
All rights reserved. Reproduction or distribution without permission is prohibited.
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, Ristinen, Kraushaar, Brack Energy and the Environment Chapt 1 Solutions
Chapter 1: Energy Fundamentals
Odd-numbered problems
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•Problem 1.3 : Cart on a horizontal surface
Given: F = 10lb and d = 10f t
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F ×d=W
10lb × 10f t = 100f t · lbs
j
100f t · lbs × 1.36 = 136 joules
f t · lb
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•Problem 1.7 : Tons of coal per person
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From Table 1.1: 98 QBtu/yr used in U.S.
U.S. population approximately 300 × 106 people.
1 ton coal
98 × 1015 Btu × 7
= 3.6 × 109 tons
2.7 × 10 Btu
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3.6 × 109 tons tons
Then: 6
= 12 , approximately.
300 × 10 people yr · person
•Problem 1.11 : Windmill heats water
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f t3 lb
40 gallons × 0.1337 × 62.4 3 = 334 lb
gal ft
Btu
334 lb × 1 × 50°F = 16, 700 Btu needed
lb · °F
1, 055 j
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16, 700 Btu × = 17.6 × 106 j needed
Btu
j
1400 W = 1400
sec
6
17.6 × 10 j
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= 12, 600 seconds = 210 minutes = 3.5 hours
1400j/s
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, Ristinen, Kraushaar, Brack Energy and the Environment Chapt 1 Solutions
Multiple choice problems
•Problem 1.1 : Product with exponentials
Answer: f)
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(5 × 6 × 7) × 10(5+6+7) = 210 × 1018 = 2.1 × 1020
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•Problem 1.3: Mass on string
Answer: c)
Initially: P.E. = mgh (see page 113)
m
= 5kg × 9.8 2 × 2m
s
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2
m
= 98kg 2
s
= 98Joules
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•Problem 1.5 : U.S. consumption vs. India
Answer: d)
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50
From Fig. 1.3: = 12.5
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•Problem 1.7 : Average personal power
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Answer: b)
3000C = 3 × 106 cal
cal j 1 day 1 hour j
3 × 106 × 4.184 × × = 145 = 145 watts
day cal 24 hours 3600 sec sec
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•Problem 1.9 : Fossil fuel percentage of energy use
Answer: c)
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From Table 1.1: 18.5 + 27.3 + 36.1 = 81.9
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, Ristinen, Kraushaar, Brack Energy and the Environment Chapt 1 Solutions
•Problem 1.11 : Energy in a pound
Answer: b)
1 lb = 0.454 kg
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mc2 = 0.454 × (3 × 108 )2 = 4.1 × 1016
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•Problem 1.13 : Math
Answer: c)
4.8 × 3.6
× 109+5−10 = 6.2 × 104
2.8
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