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Suppose a power plant uses a Carnot engine to generate electricity, using the atmosphere at 300 K as the low-temperature reservoir. Suppose the power plant produces 1*10^6 J of electricity with the hot reservoir at 500 K during Day One and then produces 1*10^6 J of electricity with the hot reservoir at 600 K during Day Two. The thermal pollution was:  a. greatest on Day One. b. greatest on Day Two. c. the same on both days. d. zero on both days.

1.1 )

One kilogram of water at 1.00 atm at the boiling point of 100°C is heated until all the water vaporizes. What is its change in entropy? (For water, Lv = 2.26*10^6 J/kg)  a. 12 100 J/K b. 6 060 J/K c. 3 030 J/K d. 1 220 J/K
2 )
What is the change in entropy (delta S) when one mole of silver (108 g) is completely melted at 961°C? (The heat of fusion of silver is 8.82 *10^4 J/kg.)  a. 5.53 J/K b. 7.72 J/K c. 9.91 J/K d. 12.10 J/K.

3)

A cylinder containing an ideal gas has a volume of 2.0 m3 and a pressure of 1.0 *10^5 Pa at a temperature of 300 K. The cylinder is placed against a metal block that is maintained at 900 K and the gas expands as the pressure remains constant until the temperature of the gas reaches 900 K. The change in internal energy of the gas is 6.0 *10^5 J. Find the change in entropy of the block associated with the heat transfer to the gas.  a. 0 b. +670 J/K c. - 440 J/K d.-1 100 J/K  

The surface of the Sun is at approximately 5 700 K and the temperature of the Earth's surface is about 290 K. What total entropy change occurs when 1 000 J of heat energy is transferred from the Sun to the Earth?  a. 2.89 J/K b. 3.27 J/K c. 3.62 J/K d. 3.97 J/K
5)
1 On an average diet, the consumption of 10 liters of oxygen releases how much energy? (4.8 kcal are released per liter of oxygen consumed.)  a. 48 kJ b. 200 kJ c. 4.2 kJ d. 4 200 kJ
6)
A person consumes 2 500 kcal/day while expending 3 500 kcal/day. In a month’s time, about how much weight would this person lose if the loss were essentially all from body fat? (Body fat has an energy content of about 4 100 kcal per pound.)  a. 1 pound b. 2 pounds c. 7 pounds d. 15 pounds
7)
A pound of body fat has an energy content of about 4 100 kcal. If a 1 400-kg automobile had an equivalent amount of translational kinetic energy, how fast would it be moving? (0.447 m/s = 1 mph, 1 kcal = 4 186 J)  a. 3.1 mph b. 14 mph c. 75 mph d. 350 mph.

Suppose the ends of a 20-m-long steel beam are rigidly clamped at 0 C to prevent expansion. The rail has a cross-sectional area of 30 cm2. What force does the beam exert when it is heated to 40C? (alpha steel = 1.1 *10^5/C, Ysteel = 2.0 * 10^11 N/m2).
a. 2.6 * 105 N

Estimate the volume of a helium-filled balloon at STP if it is to lift a payload of 500 kg. The density of air is 1.29 kg/m3 and helium has a density of 0.178 kg/m3.
a. 4 410 m3 b. 932 m3 c. 450 m3 d. 225 m3

10)

Twenty grams of a solid at 70°C is place in 100 grams of a fluid at 20°C. Thermal equilibrium is reached at 30°C. The specific heat of the solid:  a. is equal to that of the fluid. b. is less than that of the fluid. c. is more than that of the fluid.

11) A puddle holds 150 g of water. If 0.50 g of water evaporates from the surface, what is the approximate temperature change of the remaining water? (Lv = 540 cal/g)  a. +1.8 C° b. –1.8 C° c. +0.18 C° d. - 0.18 C°
100 g of liquid nitrogen at its boiling point of 77 K is stirred into a beaker containing 500 g of 15°C water. If the nitrogen leaves the solution as soon as it turns to gas, how much water freezes? The heat of vaporization of nitrogen is 48 cal/g and that of water is 80 cal/g.
a. none b. 29 g c. 68 g d. 109 g
Ans: None How do you solve? How would you calculate how much water froze if this weren't the case?

asked Nov 7, 2014 in PHYSICS by mthskey12 Rookie
edited Nov 7, 2014 by bradely

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