PHYS Brooks. Select the response that best answers the given statement.

Transcription

1 Name: Section: PHYS Brooks The Final Exam is comprehensive and will cover chapters To review chapters 1-11, refer to the prior reviews for these chapters. This review only covers material from chapters The Final Exam will include 1 or 2 problems from each chapter (1-21). This practice test is similar to the actual test. The Final Exam will consist of about 30 questions designed to be completed in about 2 hours. This practice test does not cover every single concept that may be on the actual Final Exam. An answer key is included, but there are no solutions to the problems. Students need to work out all solutions on their own. Select the response that best answers the given statement. 1. An object in equilibrium always: a. is not moving b. is not accelerating c. has no forces acting upon it d. has all forces acting upon it of equal magnitude. 2. If the net force on an object is zero, then the object must be at rest. a. true b. false c. cannot say unless gravity is negligible 3. Materials which behave as described by Hooke's law have a constant elastic force. a. true b. false c. only until the proportionality limit is reached 4. What is the stress in a 1.33 meter long, 1.0 mm diameter, brass wire which has been stretched 1.5 mm? Young's modulus for brass is 1.00 x N/m 2 a. 89. N/m 2 b. 8.9 x 10 5 N/m 2 c. 1.1 x N/m 2 d. 1.1 x 10 8 N/m 2 5. For a horizontal beam spanning an opening, the shear stress is greatest at: a. the center b. one third the distance from each end c. the end d. one quarter the distance from each end

2 6. For a concrete column of constant cross sectional area, what is the maximum possible height if the compressible strength is 2.0 x 10 7 N/m 2? The density of concrete is 2.3 x 10 3 kg/m 3. a km b km c. 89 m d. 47 m 7. A 1.0 cm diameter cable is continuously lowered into the ocean supporting its own weight. At a depth of 1.5 km it breaks. A new replacement cable made of the same glass fiber only with twice the diameter (2.0 cm) would be expected to break at what depth? a. 1.5 km b. 3.0 km c. 4.5 km d. 6.0 km 8. What is the minimum cross sectional area required for an aluminum cable to support a 100 kg person hanging from the cable end? Assume a safety factor of 4. The tensile strength of aluminum is 2.00 x 10 8 N/m 2. a cm 2 b cm 2 c cm 2 d cm 2 9. Jason and Jane stand on opposite ends of a balanced seesaw. How far (x) is Jason from the fulcrum when Jane is 3.0 from the fulcrum? a. 2.1 m b. 1.8 m c. 4.2 m d. 3.9 m

3 10. What minimum mass counterweight (C) must be used in the tower crane to enable it to lift kg? a. 3.2 Mg b. 4.6 Mg c. 5.9 Mg d. 6.5 Mg 11. An aluminum rivet must withstand a shear force of N. Using a safety factor of 5, what area rivet must be used? a cm 2 b. 1.0 cm 2 c. 2.0 cm 2 d. 2.5 cm A 1.9 m long flagpole of uniform 0.75 kg mass is attached to the wall by a bracket making a 40 degree angle with the wall. The bracket must exert what torque to support the pole? a. 4.5 N-m b. 5.3 N-m c N-m d N-m 13. At a point in a fluid a. pressure downward is greater than pressure sideways because of gravity b. pressure downward is greater than pressure upward c. pressure is the same in all directions only if the fluid is at rest d. pressure downward equals pressure sideways 14. A dam is 32 m high and 1200 m wide. Calculate the total horizontal force exerted on the dam by the water on the dam. a. 6.0 x 10 9 N b. 9.9 x 10 9 N c. 1.4 x N d. 1.8 x N 15. One atmosphere is equal to: a. 1 bar b x 10 5 N/m 2 c x 10 5 N/m 2 d. 1 Pascal

4 16. A water barometer is about how high? a. 76 cm b inches c. 760 ft d. 10 m 17. Consider ice cubes floating in a full glass of water. When they melt: a. water overflows the edge b. the water level drops c. the water level remains the same 18. A 1.0 cm 3 sphere of copper (specific gravity 8.9) is lowered by string into a bucket of gasoline (0.68 specific gravity). It seems to weigh how much less? a. 6.7 x 10-3 N b. 8.9 x 10-3 N c. 6.8 x 10-4 N d. 2.2 x 10-3 N 19. A 2.5 cm diameter sphere just barely floats in water. What is its weight? a. 1.0 mn b. 4.1 mn c. 8.2 mn d. 24 mn 20. An incompressible fluid flows through a cylindrical pipe. When the radius doubles, the velocity of flow: a. doubles b. triples c. quadruples d. stays the same 21. Water is pumped throughout a neighborhood. It moves 1.3 m/s through a 5.5 cm diameter pipe under 4.0 atm pressure at the bottom of a hill. What is its speed when it reaches the top of the 9.0 m hill where the pipe narrows to 4.2 cm diameter? Viscosity can be neglected. a. 2.2 m/s b. 1.7 m/s c m/s d m/s

5 22. A 20. N force is applied to the input 1.7 cm diameter piston of a hydraulic lift. What lifting force is produced at the output? a. 1.4 KN b. 1.6 x 10 2 N c. 82. N d. 20. N 23. If A is the amplitude of a vibrating mass on a spring, then the mass in one period travels a distance: a. 0 b. A c. 2 A d. 4 A 24. In Simple Harmonic Motion, the velocity is greatest at: a. maximum acceleration b. minimum acceleration c. maximum displacement d. maximum stored energy 25. A simple harmonic oscillator has an amplitude of 5.0 cm, a spring constant 5.0 N/m, and a maximum speed of 10. m/s. What is the speed when it reaches half of the amplitude? a. 8.7 m/s b. 5.0 m/s c. 7.6 m/s d. 2.5 m/s 26. A 300 gram mass is oscillating on a spring (spring constant 30 N/m). The damping force is proportional to velocity (F d = -bv). This friction reduces the oscillation frequency to 1.4 Hz. What is the damping constant b? a. 2.9 N-s/m b. 4.3 N-s/m c. 6.7 N-s/m d. 8.1 N-s/m 27. What length simple pendulum produces a "seconds" clock (i.e. the half period is 1.00 second)? a cm b cm c cm d cm 28. Peter notices a lamp hung by a light chain to the ceiling. Peter counts 85.0 cycles in 592 seconds. How high is the ceiling above the lamp? a m b m c m d m 29. A wave traveling 12 m/s has a frequency of 3.0 Hz. How far is it from a crest to an adjacent trough? a. 1.0 m b. 2.0 m c. 3.0 m d. 4.0 m

6 30. The tension in a stretched rubber cord, of mass 12.0 grams and length 2.0 meters, is 54 mn. What is the speed of a transverse wave? a. 2.1 m/s b. 3.0 m/s c. 4.5 m/s d. 9.0 m/s 31. Given that iron rails have an elastic modulus of 100 x 10 9 N/m 2 and density 7.9 grams/cc, what is the speed of sound in the rails? a. 1.1 x 10 5 m/s b. 3.2 km/s c. 3.6 km/s d. 4.2 km/s 32. If the intensity of light reaching the earth from the sun is approximately 1 kw/m 2, what is the intensity leaving the solar surface? (sun diameter = 14 x 10 8 m, earth diameter = 12.7 x 10 6 m, earth-sun distance = 1.5 x m) a. 2.1 x 10 2 kw/m 2 b. 4.6 x 10 4 W/m 2 c. 2.1 x 10 5 W/m 2 d. 4.6 x 10 7 W/m Consider a transverse wave represented by the function y = 2.3 sin (1.9x t) where y, x, and t are in meters, meters, and seconds respectively. Determine the period in seconds. a. 3.3 b c. 2.3 d. 13. e Consider a transverse wave represented by the function y = 2.3 sin (1.9x t) where y, x, and t are in meters, meters, and seconds respectively. Determine the speed in m/s. a. 3.3 b c. 2.3 d. 13. e Consider a transverse wave represented by the function y = 2.3 sin (1.9x t) where y, x, and t are in meters, meters, and seconds respectively. What is the displacement in meters at x = 4.0 m at t = 200 ms? a b c d A string fixed at both ends vibrates in its 3rd overtone with a distance between nodes of 30 cm. How long is the string? a. 7.7 cm b. 10 cm c. 90 cm d. 1.2 m

7 37. The 1st overtone of a violin string is 576 Hz. Which of the following is not a possible harmonic? a KHz b KHz c Hz d Hz 38. The result of "interfering" waves is always smaller than the original waves. a. True b. False 39. What is the ratio of the speed of sound in air at freezing temperature (0 C) to the speed at room temperature (20 C)? a b c d The intensity of sound is often expressed in: a. watts b. decibels c. Pascals d. Newtons 41. Frequencies of sound higher than 20 Khz are called: a. supersonic b. infrasonic c. transonic d. ultrasonic 42. An 80 db sound has which of the following intensities? a W/cm 2 b W/cm 2 c W/cm 2 d W/cm How many db is an intensity of 10-5 W/m 2? a. 50 b. 70 c. 5 d Which of the following is not a vibration mode for a tube closed at one end? a. 1st overtone b. 1st harmonic c. 3rd harmonic d. 43rd harmonic 45. Consider a closed 30.0 cm long organ pipe. What is the frequency of the 2nd overtone when the sound speed is 336 m/s? a Khz b Khz c Khz d Khz

8 46. There is constructive interference of two coherent sound waves when the path difference is how many wavelengths? a. an integer b. any half integer c. half an odd integer d. an even integer plus one half 47. One has destructive interference of two coherent sound waves when the path difference is how many wavelengths? a. an odd integer b. an even integer c. half an even integer d. half an odd integer 48. Assume ultrasound waves travel through the body of an animal at 1540 m/s. If a 30,000 Hz signal were reflected off a portion of a heart which was moving toward the observer at 4 m/s, what frequency signal would return to the stationary observer? a Hz b Hz c Hz d Hz 49. Beats are produced when two sound waves have: a. the same frequency b. the same intensity c. slightly different frequencies d. slightly different intensities 50. Suppose a boat moving at 6.0 m/s creates a bow wave at an angle of 42 with the line of track. What is the speed of the surface water waves? (From section This concept will not be on the Final Exam.) a. 3.0 m/s b. 4.0 m/s c. 5.0 m/s d. 9.0 m/s 51. A certain material has 2.8 x atoms/m 3. Estimate the distance between neighboring atoms: a nm b nm c nm d nm 52. At 376 C and 1.00 atm pressure, a certain gas occupies 7.25 m 3. If the temperature decreases to 186 C with the pressure remaining constant, what is the final volume? a m 3 b m 3 c m 3 d m 3

9 53. How many molecules are contained in a gas at 3.5 atm, 194 F, and occupying 33 m 3? a. 2.3 x b. 1.2 x c. 4.4 x d x Which of the following is not an assumption of the basic kinetic theory? a. the number of molecules is large b. molecules obey Newton's laws c. molecules lose energy hitting the walls and thereby exert pressure d. molecules spend a high percentage of their time separated from neighbors 55. The pressure of the gas depends upon a. average speed squared b. average squared speed c. square of the average speed d. root-mean-square speed 56. What is the average translational kinetic energy of molecules at 5500 K (the approximate temperature of the sun's surface)? a. 1.1 x ev b ev c ev d ev 57. Estimate the rms speed of hydrogen atoms (1.67 x kg each) at 5500 K. a. 1.4 x 10 8 m/s b. 6.3 x 10 5 m/s c. 9.0 km/s d. 12 km/s 58. Which of the following is not a unit of heat? a. Joule b. calorie c. watt d. N-m 59. The mechanical equivalent of heat says a. 1 cal = J b. 1 cal = 1 J c. 1 J = cal d. 1 kcal = 1 J 60. Temperature is a measure of the average: a. total energy of individual molecules b. kinetic energy of individual molecules c. total energy of all molecules in a sample d. total kinetic energy of all the molecules

10 61. The specific heat of liquid water is unusual in that it is: a. much greater than most metals b. about equal to that of most metals c. much less than most metals d. much less than frozen water 62. Four moles of Helium at 15 C are isothermally expanded from 72 liters to 233 liters. How much work did the gas do? a KJ b KJ c J d J 63. When the absolute temperature of an object triples, its radiation emitted is how many times more? a. 3 b. 27 c. 81 d Estimate the power radiated from a human body approximating it to be a black body at 37 C with a surface area of 1.5 square meters surrounded by walls at 20 C a Kw b Kw c. 7.1 Kw d Kw 65. The emissivity of most stars is close to one so they can be treated as "black bodies". Consider two stars, the second having twice the surface temperature and five times the radius of the first. How does the power radiated from the second compare to the first? a. 10 times b. 16 times c. 25 times d. 400 times 66. A wall consists of a 10. cm thick layer of brick (0.84 J/s-m-C), then a 1.3 cm thickness of wood (0.1 J/s-m-C), 10 cm of fiberglass (0.048 J/s-m- C), and a final 1.3 cm layer of wood. How much heat conducts through 30 m 2 area of this wall if the temperature difference across the wall is 36 F? a KW b KW c KW d. none of these 67. Lead melts at 227 C. Its specific heat is 130 J/kg-C and heats of fusion and vaporization 0.25 x 10 5 J/kg and 8.7 x 10 5 J/kg respectively. How much heat is required to heat up and melt 4.0 kg of lead originally at 20 C? a. 3.5 MJ b. 2.7 MJ c MJ d MJ

11 68. A single food CALORIE is enough energy to raise 1.0 kg how high? a. 43 cm b. 72 cm c Km d Km 69. An ideal gas undergoing a "free expansion": a. does positive work b. increases its internal energy c. decreases its internal energy d. does not change its internal energy 70. The sun transfers heat to the planets primarily by: a. conduction b. forced convection c. radiation d. natural convection 71. One hundred grams of steam at 100 C is cooled to form ice at -10 C. How much energy was released? a x 10 4 cal b x 10 4 J c x 10 4 cal d x 10 4 J 72. Which graph represents an isothermal process? a. A b. B c. C d. D 73. Which of the following is not a heat engine: a. gasoline engine b. the Carnot cycle c. gas stove d. refrigerator operated in reverse 74. An engine takes in 4.7 calories of heat and discharges 3.5 calories of heat. What is its efficiency? a. 26% b. 33% c. 74% d. 134%

12 75. A Carnot engine takes in 4.7 heat calories at 1000 C and has an efficiency of 37%. It discharges heat at what lower temperature? a. 630 C b. 630 K c. 529 K d. 529 C 76. Bill drops a 50 gram (0 C) ice cube into a large pond which is at 20 C. What is the total entropy change of the total process? a. 3.7 J/K b. 4.7 J/K c. 5.4 J/K d. 76. J/K ANSWER KEY 1. b 2. b 3. b 4. d 5. c 6. c 7. a 8. b 9. a 10. d 11. a 12. a 13. d 14. b 15. c 16. d 17. c 18. a 19. c 20. c 21. a 22. a 23. d 24. b 25. a 26. a 27. d 28. a 29. b 30. b 31. c 32. d 33. b 34. d 35. d 36. d 37. b 38. False 39. b 40. b 41. d 42. c

13 43. b 44. a 45. b 46. a 47. d 48. d 49. c 50. b 51. d 52. a 53. a 54. c 55. b 56. d 57. d 58. c 59. c 60. b 61. a 62. a 63. c 64. b 65. d 66. a 67. d 68. d 69. d 70. c 71. a 72. b 73. c 74. a 75. d 76. b

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15 METRIC PREFIXES Prefix: Symbol: Magnitude: Yotta- Y Zetta- Z Exa- E Peta- P Tera- T Giga- G 10 9 Mega- M 10 6 myria- my 10 4 kilo- k 10 3 hecto- h 10 2 deka- da 10 Prefix: Symbol: Magnitude: deci- d 10-1 centi- c 10-2 milli- m 10-3 micro nano- n 10-9 pico- p femto- f atto- a zepto- z yocto- y 10-24