Practice Quiz 21

Choose the best answer

  1. Heat is
    1. energy in transit from high temperature system
      to a low temperature system.
    2. the total kinetic energy of the particles of a
      system.
    3. the total energy of the particles of a system.
    4. a measure of the average kinetic energy of the
      particles of a system.
    5. the total potential energy of the particles of a
      system.
    Answer: A

  2. Calculate the amount of heat energy that will
    change the temperature of 0.45 kg of water (specific heat
    capacity 4180 J ⁄ kg ⁄ �C) by 32 �C.
    1. 67089.395 J
    2. 60192 J
    3. 84581.711 J
    4. 48543.292 J
    5. 20216.106 J
    Answer: B

  3. A alead metal (specific heat capacity 130 J ⁄ kg ⁄ �C)
    of mass 9 kg is dropped from a height of 90 m.
    As it hits the ground, it absorbs half of its
    kinetic energy as heat energy. By how much does
    its temperature increase?
    1. 5.113 �C
    2. 1.349 �C
    3. 3.392 �C
    4. 6.094 �C
    5. 4.728 �C
    Answer: C

  4. A 0.95 kg of aluminum metal (specific heat capacity 900 J ⁄ kg ⁄ �C)
    at a temperature of 115 �C is mixed with 9 kg of water (specific
    heat capacity 4180 J ⁄ kg ⁄ �C) at a temperature of 34 �C. Calculate the
    equilibrium temperature of the mixture.
    1. 26.715 �C
    2. 40.781 �C
    3. 13.256 �C
    4. 62.482 �C
    5. 35.8 �C
    Answer: E

  5. 1 kg of a certain substance at a temperature of
    115 �C is mixed with 5 kg of water (specific heat capacity
    4180 J ⁄ kg ⁄ �C) at a temperature of 36 �C.
    The equilibrum temperature of the mixture is found to be
    47 �C. Calculate specific heat capacity of the substance.
    1. 3035.414 J ⁄ kg ⁄ �C
    2. 5655.746 J ⁄ kg ⁄ �C
    3. 4420.343 J ⁄ kg ⁄ �C
    4. 3380.882 J ⁄ kg ⁄ �C
    5. 6214.574 J ⁄ kg ⁄ �C
    Answer: D

  6. Calculate the heat energy required to vaporize 8 kg
    of water (Latent heat of vaporization 2.26e6 J ⁄ kg).
    1. 27637629.416 J
    2. 11396127.165 J
    3. 32629957.26 J
    4. 18080000 J
    5. 2872454.438 J
    Answer: D

  7. During vaporization, the system comprises of
    1. a mixture of liquid and gas phases.
    2. pure liquid phase.
    3. a mixture of solid and gas phases.
    4. a mixture of solid, liquid and gas phases.
    5. pure gas phase
    Answer: A

  8. Calculate the amount of heat energy required to
    change 0.691 kg of ice at a temperature of -5 �C to water at a
    temperature of 30 �C. (specific heat capacities
    of ice, water and steam are 2090, 4180, 2010 J ⁄ kg ⁄ �C
    respectively. Latent heat of fusion and vaporization of water are
    3.34e5, 2.26e6 J ⁄ kg respectively.)
    1. 551306.411 J
    2. 242718.763 J
    3. 503050.923 J
    4. 425649.298 J
    5. 324666.35 J
    Answer: E

  9. Calculate the amount of heat energy required to
    change 0.256 kg of ice at a temperature of -50 �C to steam at a
    temperature of 120 �C. (specific heat capacities
    of ice, water and steam are 2090, 4180, 2010 J ⁄ kg ⁄ �C
    respectively. Latent heat of fusion and vaporization of water are
    3.34e5, 2.26e6 J ⁄ kg respectively.)
    1. 1172260.707 J
    2. 1380492.069 J
    3. 808115.2 J
    4. 323922.593 J
    5. 1078275.593 J
    Answer: C

  10. Radiation is a way of transfer of heat
    1. by means of movement of air molecules.
    2. by means of propagation of electromagnetic waves.
    3. by means of the actual movement molecules.
    4. by means of collisions of neighboring molecules.
    5. by means of diffusion.
    Answer: B

  11. A rod made of copper (thermal conductivity 397 J ⁄ s ⁄ m ⁄ �C)
    has a length of 3.6 m and a cross-sectional radius of 0.0225 m.
    Its left end and right end are at temperatures of 40 �C and 85 �C
    respectively. Calculate the amount of energy transferred
    from the left end to the right end in 36 minutes.
    1. 17047.833 J
    2. 14707.366 J
    3. 19084.87 J
    4. 12931.202 J
    5. 3120.936 J
    Answer: A

  12. An spherical object of radius 0.4 m and emissivity 0.4 is at a
    temperature of 50 �C. Its enviornment is at a temperature of 34 �C.
    Calculate the amount of radiation energy emitted
    by the object in 7 s.
    1. 4767.716 J
    2. 5916.301 J
    3. 4071.07 J
    4. 3492.793 J
    5. 2835.97 J
    Answer: D

  13. An spherical object of radius 0.2 m and emissivity 0.2 is at a
    temperature of 85 �C. Its enviornment is at a temperature of 19 �C.
    Calculate the net rate of emission of radiation of
    the object.
    1. 79.49 W
    2. 60.147 W
    3. 42.708 W
    4. 90.105 W
    5. 52.467 W
    Answer: E