The air in an automobile engine at 20C is compressed from an initial pressure of 1.0 atm and a volume of 200 cm3 to a volume of 20 cm3 . Find the temperature if the air behaves like an ideal gas ( = 1.4) and the compression is adiabatic.
a. 730C
b. 460C
c. 25C
d. 50C
e. 20C
[Ques. 2] Find the specific heat (in cal/mole K) of a gas kept at constant volume when it takes 1.0 104 J of heat to raise the temperature of 5.0 moles of the gas 200 K above the initial temperature.
a. 7.5
b. 5.0
c. 2.4
d. 10
e. 20
[Ques. 3] Five gas molecules are found to have speeds of 100, 200, 300, 400, and 500 m/s. The rms speed (in m/s) is
a. 390.
b. 300.
c. 360.
d. 330.
e. 320.
[Ques. 4] Suppose a box contains about 5.0 1021 hydrogen atoms at room temperature (21C). Determine the thermal energy of these atoms.
a. 10 J
b. 20 J
c. 30 J
d. 5.0 J
e. 1.0 J
[Ques. 5] The average translational speed of a nitrogen molecule at room temperature (20C) is approximately (in m/s)
a. 100.
b. 500.
c. 300.
d. 700.
e. 200.
[Ques. 6] The average kinetic energy of a nitrogen molecule at room temperature (20C) is
a. 2 1021 J.
b. 4 1021 J.
c. 6 1021 J.
d. 8 1021 J.
e. 1 1020 J.
[Ques. 7] A container having a volume of 1.0 m3 holds 5.0 moles of helium gas at 50C. If the helium behaves like an ideal gas, the average kinetic energy per molecule is
a. 6.7 1020 J.
b. 1.0 1021 J.
c. 1.0 1020 J.
d. 6.7 1021 J.
e. 1.3 1020 J.
[Ques. 8] A container having a volume of 1.0 m3 holds 5.0 moles of helium gas at 50C. If the helium behaves like an ideal gas, the total energy of the system is
a. 2.0 104 J.
b. 2.5 104 J.
c. 1.7 103 J.
d. 1.5 103 J.
e. 4.0 104 J.
[Ques. 9] One end of a copper rod is in thermal contact with a hot reservoir at T = 500 K and the other end is in thermal contact with a cooler reservoir at T = 300 K. Find the entropy change of each reservoir, and the total entropy change, when 8 000 J of heat energy are conducted from one end of the rod to the other with no change in the temperature distribution in the rod.
[Ques. 10] Every second at Niagara Falls, some 5000 m3 of water falls a distance of 50 m. What is the increase in entropy per second due to the falling water? (Assume a 20C environment).
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