PHYS 210 Exam 2, Spring 2008

1 @Assume that a diatomic gas of 3.0 moles has an intemal energy of 10 KJ. Determine the temperature of the gas after it has reached erquilibrium Marks: 5 Choose one answer. a. 1650K x ® b160KY c. 270K x d.400K x e. 800K * Correct Marks for this submission: 5/5. 10 Marks: 5 @A helium-filled balloon has a volume of 1.0 m 3. As it rises in Earth’s atmosphere, its volume expands . The initial temperature is 20 °C and the initial pressure is 1.0 atm. The final temperature is -40 °C and the final pressure is 0.1 atm. What is the new volume of the balloon (in m? y? Choose one answer. Correct Marks for this submission: 5/5. © a80V¥ b.10 x c.6.0 x d 4.0 x e. 16 x 11 Marks: 5 @In the cycle shown in the Figure, AB and CD are isotherms. The working substance is an ideal gas. For the part D toA determine the sign of the following thermodynamic quantities: Q, AE At and AS: (1) Q>0, AE, , >0,AS>0 (2) Q>0, AE, >0, A S<0 3) Q>0, AE it <0,AS>0 (4)Q<0, AE it <0, A S<0 (5) Q<0 , AE, >0, A S<0 P tsothermal processes Choose one answer. a. (5) x Incorrect Marks for this submission: 0/5. 12 Marks: 5 ® What is the change of entropy (in J/K) when 5.0 moles of an ideal gas at 0°C are compressed isothermally (at constant temperature) from an initial volume of 100 cm? to a final volume of 20 cm? ? (gas constant is R=8.314 J/ (K.mole) Choose one answer. a. -134 x b. 67 ¥ c.-71 x d.-191 x e. -52 x Correct Marks for this submission: 5/5. 13 Marks: 5 @A 5.0 g copper-coin is dropped from a height of 300 m above the ground. If the coin reaches the a terminal velocity (no change anymore) of 45 m/s, and the rest of the energ temperature (in °C) of the coin?. The specific heat of m/s?) Choose one answer. Correct Marks for this submission: 5/5, a. 21.0 x b.9.0 x c.10.0 x d25 x e 50 V¥ onverted to heating the coin, what is the change in 87 J/(Kg.°C), and the gravitational acceleration is 9.8 “ lf the rms-speed of helium is 1911 m/s, then the rms-speed of a water molecule is about (mass of the helium is 4g vas and mass of water is18 g) Choose one answer. a. 1911 m/s x b. 4000 m/s x c. 430 m/s x d. 900 m/s ¥ e. 8600 m/s x Correct Marks for this submission: 5/5. 15 Marks: 5 Ten kilograms of water at 0°C is mixed with 10 kg of water at 100 °C. The change in entropy (in J/K) of the system is Choose one answer. Correct Marks for this submission: 5/5, 168 JIK x -720 JIK x 480 JK x 1015 IK ¥ 242 JIK x 16 Marks: § One mole of an ideal gas is heated from a state (P; ; V; )=(0.5 atm,1.5 m? ) to a state (Pr Ve )=(1.5 atm, 4.5 m? )in sucha way that the pressure is directly proportional to the volume (p=kV, where k is a constant). If the initial temperature of the gas is LF =300 K, what is its final temperature (in K) ? Choose one answer. a. 450K x b. 3600K x c. 900K x d. 1800K x @ e.2700K ¥ Correct Marks for this submission: 5/5, ee 5 ? How much heat (in KJ) must be removed to make ice at —10°C from 2.01 kg of water at 20°C? (The specific heat of ice is 2090 J/(kg.°C)). L ,=3.33x10° J/Kg Choose one answer. a.210 x b. 190 c. 880 ¥ d. 200 e. 420 Incorrect Marks for this submission: 0/5, 18 Marks: 5 9.7 moles of an ideal gas expands isothermally at T=132°C to five times its initial volume. Find the heat flow into the system. Give your answer in kilo joules and no units with the answer and 2 figures after the decimal point (due chiffres apre le point) Answer: 17.13 Incorrect Correct answer: 52.56 Marks for this submission: 0/5