1) Pressure in a fluid decreases with depth. False 1) 2) To determine gauge pressure, add the atmospheric pressure to the absolute pressure.

Transcription

1 Exam 4 review Name TRUE/FALSE. Write 'T' if the statement is true and 'F' if the statement is false. 1) Pressure in a fluid decreases with depth. False 1) 2) To determine gauge pressure, add the atmospheric pressure to the absolute pressure. False 2) 3) In the first law of thermodynamics, Q is the heat gained by the system, that is, Q is positive if the system gains heat. True 3) 4) In the first law of thermodynamics, W is the work done on the system, that is, W is positive if work is done on the system. False 4) 5) The internal energy of an ideal gas does not depend on the pressure. 5) true 6) The buoyant force acting on an object is equal to the weight of the object. False 6) MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 7) A certain gas is compressed adiabatically. The amount of work done on the gas is 800 J. What is the change in the internal energy of the gas? A) 800 JXXX B) 0 J C) -800 J D) 400 J E) More information is needed to answer this question. 7) 8) Pressure is 8) A) proportional only to area. B) proportional to both force and area. C) proportional to force and inversely proportional to area.xxx D) inversely proportional to force and proportional to area. E) inversely proportional to both force and area. 9) You have two identical pure silver ingots. You place one of them in a glass of water and observe it to sink to the bottom. You place the other in a container full of mercury and observe that it floats. Comparing the buoyant forces in the two cases you conclude that A) the buoyant force in the water is zero and that in mercury is non-zero. B) the buoyant force in the water is equal to that in mercury. C) the buoyant force in the water is larger than that in mercury. D) the buoyant force in water is smaller than the that in mercury.xxx E) No conclusion can be made about the respective values of the buoyant forces. 9) 1

2 10) The pressure differential across a wing cross section due to the difference in air flow is explained by 10) A) Bernoulli's equation.xxx B) Torricelli's law. C) Archimedes Principle. D) Poiseuille's law. E) Pascal's Principle. 11) The Aswan High Dam is 111 m high. What is the water pressure at the foot of the dam? 11) A) Pa B) PaXXX C) Pa D) Pa E) Pa 12) Bernoulli's principle is a statement of the 12) A) conservation of linear momentum. B) conservation of angular momentum. C) conservation of kinetic energy. D) conservation of mass. E) conservation of energy.xxx 13) Salt water is more dense than fresh water. A ship floats in both fresh water and salt water. Compared to the fresh water, the volume of water displaced in the salt water is A) less.xxx B) more. C) the same. D) Cannot be determined from the information given. 14) A spar buoy consists of a circular cylinder, which floats with its axis oriented vertically. One such buoy has a radius of 1.00 m, a height of 2.00 m and weighs 40.0 kn. What portion of it is submerged when it is floating in fresh water? A) 1.30 mxxx B) 1.20 m C) 1.35 m D) 1.50 m E) 1.25 m 15) An incompressible fluid flows steadily through a pipe that has a change in diameter. The fluid speed at a location where the pipe diameter is 8.0 cm is 1.28 m/s. What is the fluid speed at a location where the diameter has narrowed to 4.0 cm? A) 0.64 m/s B) 1.28 m/s C) 2.56 m/s D) 0.32 m/s E) 5.12 m/sxxx 13) 14) 15) 2

3 FIGURE ) Water flows out of a large reservoir through an open pipe, as shown in Figure What is the speed of the water as it comes out of the pipe? A) 15.6 m/s B) 12.5 m/sxxx C) 9.90 m/s D) 14.0 m/s E) 8.86 m/s 17) A cylinder, semicircular in cross-section, 10.0 m long and 5.00 m in radius, is completely submerged in water. What is the buoyant force on the cylinder? A) N B) N C) N D) N E) NXXX 16) 17) TRUE/FALSE. Write 'T' if the statement is true and 'F' if the statement is false. 18) Heat is energy that is transferred between objects that are in thermal contact because of a temperature difference. 18) 19) Convective heat transfer can only occur if fluids mediate the energy transfer. 19) MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. FIGURE ) Refer to Figure A bimetallic strip, consisting of metal G on the top and metal H on the bottom, is rigidly attached to a wall at the left. The coefficient of linear thermal expansion for metal G is greater than that of metal H. If the strip is uniformly heated, it will A) curve downward.xxx B) curve upward. C) remain horizontal, but get longer. D) bend in the middle. E) remain horizontal, but get shorter. 20) 3

4 21) Object 1 has three times the specific heat capacity and four times the mass of Object 2. The two objects are given the same amount of heat. If the temperature of Object 1 changes by an amount T, the change in temperature of Object 2 will be 21) A) 6 T. B) 12 T.XXX C) T. D) 4 3 T. E) 3 4 T. 22) The process whereby heat flows by means of molecular collisions is referred to as 22) A) radiation. B) inversion. C) evaporation. D) convection. E) conduction.xxx FIGURE ) Consider a flat steel plate with a hole through its center as shown in Figure When the plate's temperature is increased, the hole will A) always contract. B) remain the same size. C) contract if it takes up less than half the plate's surface area. D) expand only if it takes up more than half the plate's surface area. E) always expand.xxx 23) 24) Convection can occur 24) A) only in solids. B) in solids, liquids, and gases. C) only in liquids and gases.xxx D) only in liquids. E) only in gases. 25) When you walk barefoot in a room, the floor feels cooler walking on a tile floor as compared to a wooden floor because A) tile has a smaller specific heat than wood. B) tile has a larger specific heat than wood. C) tile has a larger thermal conductivity than wood.xxx D) tile has a smaller thermal conductivity than wood. E) none of the above 26) If the absolute temperature of an object is tripled, the thermal power radiated per unit surface area of this object will (assuming that its emissivity is not affected by the temperature change) A) increase by a factor of 9. B) increase by a factor of 18. C) increase by a factor of 27. D) increase by a factor of 81.XXX E) increase by a factor of 3. 25) 26) 4

5 27) The internal energy of an ideal gas depends on 27) A) its pressure. B) its temperature, pressure, and volume. C) its temperature and pressure. D) its volume. E) its temperature.xxx 28) The point in the phase diagram where the fusion curve, the vapor pressure curve, and the sublimation curve join is called the A) double point. B) triple point.xxx C) boiling point. D) critical point. E) melting point. 28) 29) Phase changes occur 29) A) as the temperature remains the same.xxx B) as the temperature decreases. C) as the temperature increases. D) all of the above E) none of the above 30) When a vapor condenses 30) A) heat energy leaves the substance.xxx B) the temperature of the substance decreases. C) heat energy enters the substance. D) the temperature of the substance increases. 31) The heat required to change a substance from the solid to the liquid state is referred to as the 31) A) heat of condensation. B) heat of fusion.xxx C) heat of freezing. D) heat of vaporization. E) heat of melting. 32) What is the temperature of 3.0 moles of gas at a pressure of 250 kpa held in a volume of 15 L? 32) A) 200 K B) 150 KXXX C) 250 K D) 300 K E) 350 K 33) A copper sphere, 10 cm in diameter, is subjected to a pressure of N/m2. What is the change in the diameter of the sphere? The bulk modulus for copper is N/m2. A) mxxx B) m C) m D) m E) m 34) If you add 700 kj of heat to 700 g of water at 70.0 C, how much water is left in the container? The latent heat of vaporization of water is J/kg. A) 429 gxxx B) 340 g C) 258 g D) 600 g E) none 33) 34) 5

6 35) How much heat is required to change 456 g of ice at C into water at 25.0 C? The specific heat of ice is 2090 J/(kg K) and the latent heat of fusion of water is J/kg. A) 153 kj B) 224 kjxxx C) 72.5 kj D) 71.5 kj E) 112 kj 36) A 1200-kg car is being raised at a constant speed by a crane, using a 20-m long steel cable, 1.50 cm in diameter. Young's modulus for steel is N/m2. What is the change in length of the cable? A) 3.3 mm B) 3.3 m C) 6.7 cm D) 3.3 cm E) 6.7 mmxxx 37) A quantity of an ideal gas is kept in a rigid container of constant volume. If the gas is originally at a temperature of 19 C, at what temperature will the pressure of the gas double from its base value? A) 91 C B) 273 C C) 311 CXXX D) 38 C E) 122 C 38) A car starts out when the air temperature is 288 K. The air pressure in the tires is 500 kpa. After driving a while, the temperature of the air in the tires increases to 298 K. What is the pressure in the tires at that point, assuming the volume remains constant? A) 129 kpa B) 517 kpaxxx C) 483 kpa D) 507 kpa E) 532 kpa 35) 36) 37) 38) FIGURE ) An ideal monatomic gas undergoes the reversible expansion shown in Figure 18-1, where V2 = 5V1 and P2 = 3P1. What is the change in internal energy of the gas in this process, in terms of the initial pressure and volume? A) 21P1V1XXX B) 15P1V1 C) 29P1V1 D) 7P1V1 E) 14P1V1 39) 6

7 FIGURE ) An ideal gas undergoes the process a b c a shown in Figure Pa = Pc = kpa, Vb = Vc = L, Va = L, and Pb = kpa. How much work is done by the system in this process? A) 3300 JXXX B) 2300 J C) 2800 J D) 3800 J E) 3000 J 41) A reversible engine operating between 500 K and 300 K has the same efficiency as a reversible engine operating between 400 K and what lower temperature? A) 280 K B) 220 K C) 240 KXXX D) 260 K E) 200 K 42) An air conditioner with a coefficient of performance of 3.5 uses 30 kw of power. How much power is it discharging to the outdoors? A) 135 kwxxx B) 30 kw C) 75 kw D) 105 kw E) 210 kw 43) What is the change in entropy when 15.0 g of water at 100 C are turned into steam at 100 C? The latent heat of vaporization of water is J/kg. A) 0 J/K B) 90.8 J/KXXX C) -339 J/K D) J/K E) 339 J/K 44) The compressor in a certain Carnot refrigerator performs 480 J of work to remove 150 J of heat from the interior of the refrigerator. How much heat must the coils behind the refrigerator discharge into the kitchen? A) 480 J B) 150 J C) 110 J D) 330 J E) 630 JXXX 40) 41) 42) 43) 44) 45) A certain Carnot engine has Th = Tc + 35K, and an efficiency of 20.0%. What is Th? 45) A) 175 KXXX B) 140 K C) 70.0 K D) 245 K E) 210 K 46) What is the maximum efficiency of an engine operating between 500 K and 300 K? 46) A) 60% B) 20% C) 50% D) 40%XXX E) 30% 7

8 47) An athlete doing push-ups performs 650 kj of work and loses 425 kj of heat. What is the change in the internal energy of the athlete? A) 276 kj B) -225 kj C) 1075 kj D) 225 kj E) kjxxx 47) 8