A baseball outfielder throws a baseball of mass 0.15 kg at a speed of 30 m/s and initial angle of 30. What is the kinetic energy of the baseball at the highest point of the trajectory? Ignore air friction.
a. zero
c. 92 J
b. 51 J
d. 120 J
[Ques. 2] The maximum theoretical thermodynamic efficiency of a heat engine operating between hot and cold reservoirs is a function of which of the following?
a. hot reservoir temperature only
c. both hot and cold reservoir temperatures
b. cold reservoir temperature only
d. None of the above choices are valid.
[Ques. 3] A pole-vaulter clears 5.00 m. With what speed does he strike the mat in the landing area?
a. 2.70 m/s
c. 10.8 m/s
b. 9.90 m/s
d. 21.6 m/s
[Ques. 4] According to the second law of thermodynamics, which of the following applies to the heat received from a high temperature reservoir by a heat engine operating in a complete cycle?
a. must be completely converted to work
b. equals the entropy increase
c. converted completely into internal energy
d. cannot be completely converted to work
[Ques. 5] An 80,000-kg airliner is flying at 900 km/h at a height of 8.00 km. What is its total energy (kinetic + potential) if the total was 0 when the airliner was at rest on the ground?
a. 250 MJ
c. 8770 MJ
b. 478 MJ
d. 10,300 MJ
[Ques. 6] An electrical power plant manages to send 88 of the heat produced in the burning of fossil fuel into the water-to-steam conversion. Of the heat carried by the steam, 30 is converted to the mechanical energy of the spinning turbine. Which of the following choices best describes the overall efficiency of the heat-to-work conversion in the plant (as a percentage)?
a. greater than 88
c. 30
b. 64
d. less than 30
[Ques. 7] Old Faithful geyser in Yellowstone Park shoots water hourly to a height of 30 m. With what velocity does the water leave the ground?
a. 7.0 m/s
c. 24 m/s
b. 14 m/s
d. 28 m/s
[Ques. 8] A heat engine operating between a pair of hot and cold reservoirs with respective temperatures of 500 K and 300 K will have what maximum efficiency?
a. 60
c. 40
b. 50
d. 30
[Ques. 9] Two blocks are released from the top of a building. One falls straight down while the other slides down a smooth ramp. If all friction is ignored, which one is moving faster when it reaches the bottom?
a. The block that went straight down.
b. The block that went down the ramp.
c. They both will have the same speed. d. Insufficient information to work the problem.
[Ques. 10] A heat engine exhausts 4000 J of heat while performing 2000 J of useful work. What is the efficiency of the engine?
a. 15
c. 40
b. 33
d. 60
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