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Unformatted text preview: Department of Physics University of California, Berkeley Midterm Examination 1 Physics 7B, Section 3 6:00 pm  8:00 pm, 2 October 2008 Name: SID No: Discussion Section: Name of TA: Problem 1 Problem 2 Problem 3 Problem 4 Problem 5 Score: 1 Answer all five problems. Write clearly and explain your work. Partial credit will be given for incomplete solutions provided your logic is reasonable and clear. Cross out any parts that you don’t want to be graded. Enclose your answers with boxes. Express all numerical answers in SI units . Answers with no explanation or disconnected comments will not be credited. If you obtain an answer that is questionable, explain why you think it is wrong. Constants and Conversion factors Avogadro number, N A 6 . 022 × 10 23 Universal gas constant, R 8.315 J · mol 1 · K 1 = 1.99 cal · mol 1 · K 1 Boltzmann constant, k 1 . 381 × 10 23 J · K 1 StefanBoltzmann constant, σ 5 . 67 × 10 8 W · m 2 · K 4 Acceleration due to gravity, g 9.8 m · s 2 Specific heat of water 1 kcal · kg 1 · ◦ C 1 Heat of fusion of water 80 kcal · kg 1 333 kJ · kg 1 Heat of vaporization of water 539 kcal · kg 1 2260 kJ · kg 1 1 atm 1 . 013 × 10 5 N · m 2 1 kcal 4 . 18 × 10 3 J 1 hp 746 W 1 liter 10 3 cm 3 Some useful equations Δ L = αL Δ T Δ V = βV Δ T W = P dV Q = mc Δ T Q = nC Δ T, where C = C V or C P P V γ = constant T V γ 1 = constant γ = C P C V dN v dv = 4 πN m 2 πkT 3 2 v 2 e mv 2 2 kT ; v most probable = 2 kT m v = 8 kT πm v rms = 3 kT m = 3 ρ P dQ dt = σ AT 4 dQ dt = hA ( T s T a ) dQ dt = κA dT dx 2 1. [25 points] Short Questions (a) [5 points] Circle T or F for True or False T F (i) A carbon twelve, 12 C, atom has a mass of 12.0000 unified atomic mass units (u = 1 . 6605 × 10 27 kg). T F (ii) There are at least 6 . 02 × 10 23 molecules of nitrogen in a large breath ( ≤ 4 L) of air. T F (iii) If the absolute temperature of a body increases by 1%, the rate at which it radiates energy increases by a factor of 5%. T F (iv) When a system goes from equilibrium state 1 to state 2, the change in the internal energy is the same for all processes going between the two states. T F (v) For any material that expands when heated, C P is greater than C V . T F (vi) The specific heat of a monoatomic gas is greater than that of a polyatomic gas. T F (vii) Entropy is a state variable. T F (viii) The Carnot cycle drawn on an ST diagram, instead of PV diagram, is a rectangle. T F (ix) The heat of vaporization is understood in the kinetic theory of gases as a result of the random motion of molecules. T F (x) According to the principle of equipartition, energy is shared equally among the active degrees of freedom in an amount of 1 2 kT in each on average....
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This note was uploaded on 02/04/2010 for the course PHYSICS 7B taught by Professor Packard during the Spring '08 term at Berkeley.
 Spring '08
 Packard
 Physics

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