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Unformatted text preview: Quiz 3, Physics 2C, Fall 2011 MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 1) Which of the following is a WRONG statement? A) If you put a closed, sealed can of air on a hot stove burner, the air will undergo an increase in internal energy, temperature, and pressure. B) When a system does work and no heat is added to the system, its temperature decreases. C) If a system obtains 100 joules of net heat and performs 60 joules of net work, the internal energy of the system increases by 40 joules. D) During isothermal expansion, an ideal gas performs a positive work, W, which is equal by its absolute value to the change in the internal energy of the gas. E) The relation U = nC v T, where C v is molar specific heat at constant volume, is always true for ideal gas, because the internal energy of an ideal gas is completely defined by its temperature. 2) Which of the following statements is WRONG? A) If a process with an ideal gas is not quasi- static, it is not appropriate to represent it by a continuous curve on the P- V plane. B) In the first law of thermodynamics, W is positive when a net positive work is done by the system, and not on the system. C) If an ideal gas is taken from a certain initial state to a certain final state, the difference between the heat obtained by the gas and the work done by it does not depend on the process of transition between the two states. D) When a gas is changed to a liquid state, the gas absorbs energy. E) Heating water in a can may or may not be a quasi- static process depending on how uniformly the water is heated and how well it is mixed 3) Which of the following is a WRONG statement? A) In the van der Walls equation of state, (p + an 2 V 2 )(V - nb) = nRT, the term an 2 /V 2 with positive a accounts for attractive interaction between gas molecules. B) In the kinetic theory of the ideal gas, the change of momentum of a gas molecule as a result of its collision with a wall of the container is equal to mv x , where m is the mass of the molecule and v x is the component of its velocity along a direction perpendicular to the wall. C) According to the kinetic theory of the ideal gas, if all molecules of the gas double their speeds and the length of the box containing the gas doubles as well (while other dimensions of the box and the mass of the gas molecules remain the same), the pressure of the gas increases two- fold. D) A quasi- static process, which begins and ends at the same temperature, is not necessarily isothermal. E) In the van der Walls equation of state, (p + an 2 V 2 )(V - nb) = nRT, the parameter b is positive and is generally expected to be larger for a gas with a larger size of the molecules....
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