When gasoline is burned, it gives off 41 000 J/g of heat energy. If an automobile uses 14.1 kg of gasoline per hour with an efficiency of 23.0, what is the average horsepower output of the engine? (1 hp = 746 W)
a. 49.5 hp
b. 105 hp
c. 35.1 hp
d. 29.8 hp
e. 59.5 hp
[Ques. 2] Three resistors, each with resistance R1, are in parallel in a circuit. They are replaced by one equivalent resistor, R. Compare this resistor to the first resistor of the initial circuit. Which of the following statements is true?
a. The current through R equals the current through R1.
b. The voltage across R equals the voltage across R1.
c. The power given off by R equals the power given off by R1.
d. R is greater than R1.
[Ques. 3] In which system is heat usually transferred from the cooler part to the warmer part?
a. a stove as it heats up water
b. a refrigerator that is running
c. an electric fan that is running
d. none of the above, because it is impossible to transfer heat in this manner
[Ques. 4] Three resistors, with values of 3.00, 7.00, and 15.0 , respectively, are connected in parallel. What is the overall resistance of this combination?
a. 25.0
b. 1.84
c. 0.543
d. 8.33
e. 6.80
[Ques. 5] During each cycle of operation a refrigerator absorbs 55.0 cal from the freezer compartment and expels 88.0 cal to the room. If one cycle occurs every 10 s, how many minutes will it take to freeze 575 g of water, initially at 0C? (Lv = 80 cal/g)
a. 69.7 min
b. 1 390 min
c. 139 min
d. 87.1 min
e. 836 min
[Ques. 6] Three resistors with values R1, R2 and R3, respectively, are connected in parallel. Which of the following expresses the total resistance, RT, of the three resistors when connected in parallel?
a. RT = R1 + R2 + R3
b. RT = (1/R1 + 1/R2 + 1/R3)
c. RT = R1 = R2 = R3
d. RT = (1/R1 + 1/R2 + 1/R3)1
[Ques. 7] An electrical generating plant operates at a boiler temperature of 225C and exhausts the unused heat into a nearby river at 25.0C. If the generating plant has a power output of 850 megawatts (MW) and if the actual efficiency is 3/4 the theoretical efficiency, how much heat per second must be delivered to the boiler? (0C = 273 K)
a. 8 470 MW
b. 4 230 MW
c. 2 120 MW
d. 2 820 MW
e. 1 690 MW
[Ques. 8] Three resistors connected in parallel have the individual voltages labeled V1, V2 and V3, respectively. Which of the following expresses the total voltage VT across the three resistors when connected in this manner?
a. VT = V1 + V2 + V3
b. VT = (1/V1 + 1/V2 + 1/V3)
c. VT = V1 = V2 = V3
d. VT = (1/V1 + 1/V2 + 1/V3)1
[Ques. 9] An electrical generating plant operates at a boiler temperature of 218C and exhausts the unused heat into a nearby river at 24C. What is the maximum theoretical efficiency of the plant? (0C = 273 K)
a. 16
b. 62
c. 63
d. 40
e. 73
[Ques. 10] Three 4.00- resistors are connected in parallel to a 10.4-V battery. What is the current in any one of the resistors?
a. 14.4 A
b. 6.76 A
c. 2.60 A
d. 41.6 A
e. 6.40 A
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