Chapter 10-11 Pretest

1. A 3. 00 x 10-3 kg lead bullet travels at a speed of 2 1. A 3.00 x 10-3 kg lead bullet travels at a speed of 2.40 x 102 m/s and hits a wooden post. If half the heat energy generated remains with the bullet, what is the increase in temperature of the embedded bullet? (clead = 128 J/kg•°C) a. 112°C b. 137°C c. 225°C d. 259°C

1. A 3. 00 x 10-3 kg lead bullet travels at a speed of 2 1. A 3.00 x 10-3 kg lead bullet travels at a speed of 2.40 x 102 m/s and hits a wooden post. If half the heat energy generated remains with the bullet, what is the increase in temperature of the embedded bullet? (clead = 128 J/kg•°C) a. 112°C b. 137°C c. 225°C d. 259°C

2. What is the temperature increase of 4 kg of water when it is heated by an 800 W immersion heater for exactly 10 minutes? (cwater = 4186 J/kg•°C) a. 57°C b. 51°C c. 29°C d. 14°C

2. What is the temperature increase of 4 kg of water when it is heated by an 800 W immersion heater for exactly 10 minutes? (cwater = 4186 J/kg•°C) a. 57°C b. 51°C c. 29°C d. 14°C

3. Over several cycles, a refrigerator does 1 3. Over several cycles, a refrigerator does 1.73 x 104 J of work on the refrigerant. The refrigerant removes 8.11 x 104 J as heat from the air inside the refrigerator. How much energy is delivered to the outside air? a. 3.19 x 104 J b. 4.92 x 104 J c. 6.38 x 104 J d. 9.84 x 104 J

3. Over several cycles, a refrigerator does 1 3. Over several cycles, a refrigerator does 1.73 x 104 J of work on the refrigerant. The refrigerant removes 8.11 x 104 J as heat from the air inside the refrigerator. How much energy is delivered to the outside air? a. 3.19 x 104 J b. 4.92 x 104 J c. 6.38 x 104 J d. 9.84 x 104 J

4. An engine absorbs 2150 J as heat from a hot reservoir and gives of 750 J as heat to a cold reservoir during each cycle. How much work is done during each cycle? a. 750 J b. 1400 J c. 2150 J d. 2900 J

4. An engine absorbs 2150 J as heat from a hot reservoir and gives of 750 J as heat to a cold reservoir during each cycle. How much work is done during each cycle? a. 750 J b. 1400 J c. 2150 J d. 2900 J

5. A heat engine performs 2000. 0 J of net work while adding 5000 5. A heat engine performs 2000.0 J of net work while adding 5000.0 J of heat to the cold-temperature reservoir. What is the efficiency of the engine? a. 0.714 b. 0.600 c. 0.400 d. 0.286

5. A heat engine performs 2000. 0 J of net work while adding 5000 5. A heat engine performs 2000.0 J of net work while adding 5000.0 J of heat to the cold-temperature reservoir. What is the efficiency of the engine? a. 0.714 b. 0.600 c. 0.400 d. 0.286

1. Why is air an effective thermal insulator for the body?

Because air is such a poor thermal conductor.

2. A mixture of 30. 2 g of sand and 87 2. A mixture of 30.2 g of sand and 87.7 g of water has a temperature of 12.1°C. What mass of water at 85.8°C must be added to raise the final temperature of the mixture to 29.3°C? (cwater = 4.19 J/g•°C and csand = 2.01 J/g•°C)

cm∆T + cm∆T = cm∆T 2. 01(30. 2)17. 2 + 4. 19(87. 7)17. 2 =. 4. 19(m)56 cm∆T + cm∆T = cm∆T 2.01(30.2)17.2 + 4.19(87.7)17.2 = 4.19(m)56.5 m = 31.1 g