Chapter 11 - CHAPTER 11 Quick Quizzes 1. (a) Water, glass,...

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C HAPTER 11 Quick Quizzes 1. (a) Water, glass, iron. Because it has the highest specific heat ( ) 4186 J kg C ⋅° , water has the smallest change in temperature. Glass is next ( ) 837 J kg C , and iron () 448 J kg C is last. (b) Iron, glass, water. For a given temperature increase, the energy transfer by heat is proportional to the specific heat. 2. (d). The final temperatures will depend on the mass of each sample. 3. (c). 4. (c). The blanket acts as a thermal insulator, slowing the transfer of energy by heat from the air into the cube. 5. (e). The ratio of the power output of Star A to that of Star B is given by ( ) 24 4 AA BB A 42 4 B B B 41 22 22 6 4 RT Ae T AeT σπ σ == = = = 347
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CHAPTER 11 Problem Solutions 11.1 ( ) Qm cT =∆ ( ) ( )( ) 3 0.100 kg 129 J kg C 100 C 20.0 C 1.03 10 J =⋅ ° ° ° = × 1.03 kJ = 11.2 From ( ) , the change in temperature is ( ) () -3 1200 J 62 C 50 10 kg 387 J kg C Q T mc ∆= = = ° ×⋅ ° Thus, 25 C 62 C fi TT T =+ ∆=°+°= 87 C ° 11.3 The mass of water involved is ( ) 31 1 3 3 kg 10 4.00 10 m 4.00 kg m mV ρ ⎛⎞ == × = × ⎜⎟ ⎝⎠ 1 4 (a) ( ) ( ) ( )( ) 14 4.00 kg 4186 J kg C 1.00 C ° ° = 18 1.67 10 J × (b) The power input is × 9 1000 MW 1.00 10 J s , so, 18 97 1 yr 1.67 10 J 1.00 3.156 10 s Q t × = ℘× × 53.1 yr 11.4 The change in temperature of the rod is 4 1.00 31.7 C 0.350 kg 900 J kg C Q T × = = ° ° , and the change in the length is ( ) i L LT α ()( ) ( ) 1 62 24 10 C 20.0 cm 31.7 C 1.52 10 cm −− ⎡⎤ ° ° = 0.152 mm ⎣⎦ 348
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CHAPTER 11 11.5 The mechanical energy converted to internal energy in the collision is g QP Em g =∆ = h . Thus, the expected rise in temperature is ( ) ( ) () 2 9.80 m s 110 m 4186 J kg C m Q T mc m ∆= = = ° 0.258 C ° 11.6 The internal energy converted to mechanical energy in one ascent of the rope is . Since 1 g g = h Calorie 1000 calories 4186 Joules = = , ( ) 2 1 Calorie 50.0 kg 9.80 m s 10.0 m 4186 J Q ⎛⎞ == ⎜⎟ ⎝⎠ 1.17 Calorie 11.7 The internal energy converted to mechanical energy in the climb is . Thus, the required height is g g h = ( ) ( ) ( ) 3 2 500 Calories 4186 J 1 Calorie 2.85 10 m 75.0 kg 9.80 m s Q h mg = × = 2.85 km 11.8 The mass of water in the tub is ( )( ) 33 3 2 10 kg m 0.800 m 8.00 10 kg mV ρ , and the internal energy transferred to the water from the body is 5 kcal 4186 J 100 0.750 h 3.14 10 J h1 k c a l Q ⎛⎞⎛ ⎜⎟⎜ ⎝⎠⎝ × Thus, the change in the temperature of the water will be ( ) 5 2 3.14 10 J 8.00 4186 J kg C Q T mc × = ×⋅ = ° 0.0938 C ° 11.9 The mechanical energy transformed into internal energy of the bullet is 2 11 22 24 ii QK E m v m v = 2 i . Thus, the change in temperature of the bullet is ( ) 2 2 1 4 300 m s 4 128 J kg C i mv Q T = = = ⋅° 176 C ° 349
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CHAPTER 11 11.10 (a) The mechanical energy converted into internal energy of the block is () 2 1 0.85 0.85 2 i QK E m v == i . The change in temperature of the block will be ( ) ( ) 2 2 1 2 0.85 0.85 3.0 m s 2387Jkg C i mv Q T mc ∆= = = = ⋅° 3 9.9 10 C × ° (b) The remaining energy is absorbed by the horizontal surface on which the block slides. 11.11 The quantity of energy transferred from the water-cup combination in a time interval of 1 minute is () () () 3 JJ 0.800 kg 4186 0.200 kg 900 1.5 C 5.3 10 J kg C C water cup Qm c m c T ⎡⎤ =+∆ ⎣⎦ ⎛⎞⎛ =+ ° ⎢⎥ ⎜⎟⎜ ⎝⎠⎝ = × The rate of energy transfer is × = = 3 5.3 J 88 60 s s Q t 88 W 11.12 If N pellets are use, the mass of the lead is . Since the energy lost by the lead must
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This note was uploaded on 03/21/2008 for the course PY 211 / 212 taught by Professor Chilton during the Spring '08 term at N.C. State.

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Chapter 11 - CHAPTER 11 Quick Quizzes 1. (a) Water, glass,...

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