Quiz 21

1. What is the SI unit of measurement for Latent heat of fusion of a substance?

A. Joule ⁄ kilogram ⁄ (degree Celsius)
B. Joule ⁄ kilogram
C. (degree Celsius) ⁄ kilogram
D. Joule ⁄ (degree Celsius)
E. kilogram ⁄ (degree Celsius)

2. When a sample of lead (specific heat 130 J ⁄ kg ⁄ °C) is supplied with a 12000 J of heat energy, its temperature increased from 18 °C to 98 °C. Calculate the mass of the sample.

A. 1.154 kg
B. 1.453 kg
C. 1.718 kg
D. 1.92 kg
E. 0.213 kg

3. A alead metal (specific heat capacity 130 J ⁄ kg ⁄ °C) of mass 8 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?

A. 3.87 °C
B. 0.588 °C
C. 1.673 °C
D. 4.354 °C
E. 3.392 °C

4. A 0.65 kg of aluminum metal (specific heat capacity 900 J ⁄ kg ⁄ °C) at a temperature of 150 °C is mixed with 9 kg of water (specific heat capacity 4180 J ⁄ kg ⁄ °C) at a temperature of 38 °C. Calculate the equilibrium temperature of the mixture.

A. 39.715 °C
B. 5.971 °C
C. 70.702 °C
D. 16.571 °C
E. 65.706 °C

5. 0.65 kg of a certain substance at a temperature of 110 °C is mixed with 9.5 kg of water (specific heat capacity 4180 J ⁄ kg ⁄ °C) at a temperature of 28 °C. The equilibrum temperature of the mixture is found to be 47 °C. Calculate specific heat capacity of the substance.

A. 14487.832 J ⁄ kg ⁄ °C
B. 2665.945 J ⁄ kg ⁄ °C
C. 12570.625 J ⁄ kg ⁄ °C
D. 6630.048 J ⁄ kg ⁄ °C
E. 18424.664 J ⁄ kg ⁄ °C

6. Calculate the heat energy required to vaporize 4 kg of water (Latent heat of vaporization 2.26e6 J ⁄ kg).

A. 14464350.585 J
B. 9040000 J
C. 15790300.039 J
D. 1636566.955 J
E. 7765978.7 J

7. During vaporization, the system comprises of...

A. a mixture of solid, liquid and gas phases.
B. a mixture of liquid and gas phases.
C. pure liquid phase.
D. a mixture of solid and gas phases.
E. pure gas phase

8. Calculate the amount of heat energy required to change 1.77 kg of ice at a temperature of -45 °C to water at a temperature of 10 °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.)

A. 242029.055 J
B. 711552.419 J
C. 1373533.767 J
D. 831634.5 J
E. 366408.298 J

9. Calculate the amount of heat energy required to change 1.333 kg of ice at a temperature of -30 °C to steam at a temperature of 160 °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.)

A. 1534989.001 J
B. 7601420.591 J
C. 6598797.681 J
D. 5393113.194 J
E. 4259334.9 J

10. Which of the following is not a correct statement?

A. The rate of absorption of radiation by an object is proportional to the fourth power of its temperature.
B. The rate of emission of radiation by an object is proportional to the surface area of the object
C. The rate of absorption of radiation by an object is proportional to the surface area of the object.
D. The rate of emission of radiation by an object is proportional to the fourth power of its temperature.
E. The net rate of emission of radiation is equal to the difference between the emission and the absorption rate.

11. A rod made of copper (thermal conductivity 397 J ⁄ s ⁄ m ⁄ °C) has a length of 2.8 m and a cross-sectional radius of 0.0125 m. Its left end and right end are at temperatures of 20 °C and 90 °C respectively. Calculate the amount of energy transferred from the left end to the right end in 60 minutes.

A. 13572.115 J
B. 10779.878 J
C. 22469.001 J
D. 27149.41 J
E. 17538.923 J

12. An spherical object of radius 0.3 m and emissivity 0.6 is at a temperature of 75 °C. Its enviornment is at a temperature of 28 °C. Calculate the rate at which the object is emitting radiation to its enviornment.

A. 717.475 W
B. 436.198 W
C. 276.149 W
D. 567.277 W
E. 910.508 W

13. An spherical object of radius 0.8 m and emissivity 0.6 is at a temperature of 90 °C. Its enviornment is at a temperature of 10 °C. Calculate the rate at which the object is absorbing radiation from the enviornment.

A. 3059.005 W
B. 2267.106 W
C. 1764.256 W
D. 2644.283 W
E. 387.923 W

Quiz 21: