School Code : _______________________ Seat No.:______________________ Manuel S. Enverga University Foundation COLLEGE OF ENGINEERING Lucena City Saturday, March. 1, 2014 1:00 p.m. – 5:00 p.m. ELECTRONIC SYSTEM AND TECHNOLOGY SET A INSTRUCTION : Select the correct answer for each of the following questions. Mark only one answer for each item by shading the box corresponding to the letter of your choice on the answer sheet provided. STRICTLY NO ERASURES ALLOWED. NOTC means – None of the three choices. NOTE : 1 pt for correct answer on objective type of question ; 1 pt of correct computation ; 1 pt for correct choice of letter for problems that need computation. MULTIPLE CHOICE : 1. “Every object in the universe attracts every other object with a force directly proportional to the product of their masses and inversely proportional to the square of the distance separating them”. This statement is known as: a. Law of conservation of energy c. law of conservation of momentum b. Law of universal gravitation d. law of conservation of impulse 2. The gravitational force of the earth on an object varies of the _______ the distance of the object from the center of the earth. a. Inversely as b. inversely as the square of c. directly as d. directly as the square of 3. A rotating body has kinetic energy. This statement is _______. a. Sometimes true b. sometimes false c. always true d. always false 4. What type of energy is usually transmitted by rotary motion? a. Kinetic energy b. potential energy c. mechanical energy d. rest energy 5. Angular momentum is the product of ________. a. Moment of inertia and linear speed c. moment of inertia and angular speed b. Moment of area and angular speed d. moment of area and angular speed 6. “When the sum of the external torques acting on a system of particles is zero, the total angular momentum of the system remains constant”. This statement is known as: a. Conservation of energy c.conservation of linear momentum b. Conservation of impulse d. conservation of angular momentum 7. The maximum displacement of an object undergoing harmonic motion on either of its equilibrium position is called the _____ of the motion. a. Frequency b. oscillation c. period d. amplitude 8. What refers to an oscillatory motion that occurs whenever a restoring force acts on a body in the opposite direction to its displacement from its equilibrium position, with the magnitude of the restoring force proportional to the magnitude of the displacement? a. Damped harmonic motion c. simple harmonic motion b. Pendulum d. damped harmonic oscillation 9. Infrasound refers to sounds whose frequencies are below a. 20Hz b. 30Hz c. 40Hz d. 50Hz 10. What occur when the individual particles of a medium vibrate from side to side perpendicular to the direction in which the waves travel? a. Longitudinal waves b. transverse waves c. wave motions d. shock waves 11. What occurs when the resulting composite wave has an amplitude less than that of either of the original waves? a. Local interference c. constructive interference b. Ordinary interference d. destructive interference 12. What refers to a negligible body when compared to the distances involved regarding its motion? a. Particle b. atomic substance c. element d. quarks 13. The resulting force of a distributed load is always acting at: a. The center of the beam subjected to the distributed load b. The centroid of the area of the loading curve c. The 1/3 point from the higher intensity side of the loading curve
d. The 2/3 point from the higher intensity side of the loading curve 14. The sum of individual moment about a point caused by multiple concurrent forces is equal to the moment of the resultant force about the same point. This statement in known as ____. a. Pappus theorem b. D’Alembert theorem c. Varignon’s theorem d. Newton 15. Two forces acting on a particle may be replaced by a single force called resultant which can be obtained by drawing diagonal of parallelogram which has the sides equal to the given forces. This statement is known as ________. a. Pappus Theorem b. principle of transmissibility c. parallelogram law d. Varignon 16. In the analysis of friction, the angle between the normal force and the resultant force _____ the angle of friction. a. May be greater than or less b. is greater than c. is less than d. is equal to 17. What is the magnitude of the resultant force of the two forces which are perpendicular to each other? The two forces are 20 units and 30 units respectively. a. 36 b. 42 c. 25 d. 50 18. A rope is stretched between two rigid walls 40 feet apart. At the midpoint, a load of 100 lbs was placed that caused it to sag 5 feet. Compute the approximate tension in the rope. a. 206lbs b. 150 lbs c. 280 lbs d. 240 lbs 19. What is the effective component applied on the box that is being pulled a 30N force inclined at 30 ⁰ with the horizontal? a. 36.21N b. 25.98N c. 15.32N d. 20.62N 20. A post is supported by a guy wire which exerts a pull of 100N on the top of the post. If the angle between the wire and the ground is 60 ⁰, what is the horizontal component of the force supporting the pole? a. 86.6N b. 50.0N c. 76.6N d. 98.5N 21. The resultant of two forces in a plane is 400N at 120 ⁰. If one of the forces is 200lbs at 20 ⁰, what is the magnitude of the other force? a. 347.77N b. 435.77N c. 375.77N d. 453.77N 22. Referring to preceding problem, what is the angle of the other force makes with the positive xaxis? a. 114.85 ⁰ b. 104.37 ⁰ c. 124..34 ⁰ d. 144.38 ⁰ 23. Determine the resultant of the following forces: A = 600N at 40 ⁰, B = 800N at 160 ⁰ and C = 300 ⁰ a. 532.78N b. 435.94N c. 522.68N d. 627.89N 24. From the preceding problem, find the angle of the resultant that makes with the +x-axis. a. 55.32 ⁰ b. 235.12 ⁰ c. 111.57 ⁰ d. 225.81 ⁰ 25. A 300N block is at rest on an inclined plane having a slope of 1:3. If the coeffiecinet of friction between the block and the inclined plane is 0.18, solve the horizontal force neede that will cause the motion to impend up? a. 143.5N b. 231.4N c.163.8N d. 204.8N 26. A man climbs at the middle of a 150N ladder leaned against the wall. The top portion of the ladder is 4m from the ground and its bottom is 2m from the wall. Assuming smooth wall and a stopper at the bottom of the ladder to prevent slipping, find the reaction at the wall. a. 137.5N b. 145.7N c. 245.6N d. 143.5N 3 2 27. The motion of a particle is defined by the relation x = (1/3)t – 3t + 8t +2 whre x is the distance in meters and is the time in t seconds. What is the time when the velocity is zero? a. 2 sec b. 3 sec c. 5sec d. 7 sec 2 3 28. A particle moves along a straight line with the equation x = 16t + 4t – 3t where x is the distance if ft and t is the time in second. Compute the acceleration of the particle after 2 sec. a. -28ft/s2 b. -30ft/s2 c. -17ft/s2 d. -24ft/s2 29. Two cars A and B traveling in the same direction and stopped at a highway traffic sign. As the signal turns green car a accelerates at a constant rate of 1m/s 2. Two seconds later the second car B accelerates at constant rate of 1.3m/s2. When will the second car B overtakes the first car A? a. 16.27sec b. 30.45sec c. 20.32sec d. 10.45sec 30. What is the ratio of the transverse strain to the corresponding axial strain of a body subjected to uniaxial stress? a. Poisson’s ratio b. Euler’s ratio c. refractive index d. dielectric index 31. What is a structural member supported horizontally and carries transverse loading? a. Beam b. column c. arch d. shaft
32. What refers to a slender member which prevents parts of a structure moving towards each other under compressive force? a. Tie b. column c. arc d. shaft 33. Which of the following structural member is used in the transmission of torque and twist? a. Tube b. column c. panel d. shaft 34. What refers to the point in which the bending moment changes sign through a zero value? a. Critical point b. point of inflection c. point contraflexure d. point of zero stress 35. What physical property of a material refers to the highest potential difference (voltage) that an insulating material of given thickness can withstand for a specified time without occurrence of electrical breakdown through its bulk? a. Thermal expansion b. conductivity c. dielectric strength d. resistivity 36. What physical property of a material refers to the ratio of the amount of heat required to raise the temperature of a unit mass of a substance 1 degree to the heat required tl the same mass of water to 1 degree? a. Specific heat b. latent heat c. heat of fusion d. heat of fission 37. What physical property of a material refers to the temperature at which a polymer under a specified load shows a specified amount of deflection? a. Curie temperature b. specific heat c. heat distortion temperature d. thermal conductivity 38. What mechanical property of a material refers to the nominal stress at fracture in a tension test at constant load and constant temperature? a. Creep strength b. stress rupture strength c. compressive yield stressd. hardness 39. What mechanical property of a material refers to the resistance to plastic deformation? a. Rigidity b. plasticity c. ductility d. hardness 40. What parameter is definesd as the temperature at which the toughness of the material drops below some predetermined value, usually 15ft-ft? a. Nil ductility temperature c. thermal conductivity b. Curie temperature d. heat distortion temperature 41. What is obtained by repeatedly loading a specimen at given stress levels until it fails? a. Elastic limit b. endurance limit c. creep d. all of the choices 42. What dimensional property of a material refers to the deviation from edge straightness? a. Lay b. out of flat c. camber d. waviness 43. What is a polymer production process that involves forming a polymer chain containing two different monomer? a. Copolymerization b. blending c. alloying d. cross-linking 44. What is the generic name of a class of polYmer which is commercially known as “ nylon”? a. Polyacetals b. polyamide c. cellulose d. polyester 45. What refers to the tendency for polymers and molecular materials to form with an ordered, spatial, three-dimensional arrangement of monomer molecules? a. Stereospecificity b. conductivity c. retentivity d. spatial configuration 46. What is the amount of energy required to fracture a given volume of material? a. Impact strength b. endurance limit c. creep strength d. stress rupture 47. What refers to the need, want or desire for a product backed by the money to purchase it? a. Supply b. demand c. product d. good 48. Under conditions of perfect competition, the price at which any given product will be supplied and purchased is the price that will result in the supply and the demand being equal. This statement is known as the : a. Law of diminishing return b. law of supply c. law of demand d. law of supply and demand 49. What do you call any particular raw material or primary product such as cloth, wool, flour, coffee, etc.? a. Utility b. necessity c. commodity d. stock 50. What is defined as the interest on a load or principal that is based only on the original amount of the loan or principal? a. Effective rate of interest b. nominal rate of interest c. compound interest d. simple interest 51. A solid shaft 2.0m long is transmitting 27kN.m torque. If the shear modulus of the shaft material is 85 GPa and the allowable shearing stress is 70MPa, determine the angle of twist between the two ends of the shaft.
a. 1.52 ⁰ b. 1.02 ⁰ c. 1.44 ⁰ d. 1.32 ⁰ 52. Determine the maximum shearing stress in a helical steel spring composed of 20 turns of 20mm diameter wire on mean radius of 80mm when the spring is supporting a load of 20 kN. a. 529MPa b. 370MPa c. 25MPa d. 121MPa A racing car travels around the horizontal track that has a radius of 300m. the car increases its speed at a constant rate of 7m/s2 starting from rest. 53. Which of the give the time needed for it to reach an acceleration of 8m/s 2? a. 3.87sec b. 4.87sec c. 3.41sec d. 2.23sec 54. Which of the following gives the normal acceleration of the car at the time referring to previous problem? a. 3.78m/s2 b. 4.78m/s2 c. 3.41m/s2 d. 2.25m/s2 55. A man can exert a maximum pull of 1000N but wishes to lift a new stone door for his cave 20000N. if he uses a lever how much closer must the fulcrum be to the stone than to his hand? a. 10times nearer b. 20 times farther c. 10 times farther d. 20 times nearer 56. The three concurrent forces acting on the body as shown in figure 2 are in equilibrium. Which of the following gives the vertical component of the 77.8kN force? a. 76.8 b. 70.2 c. 73.2 d. 65.3 57. Two men are just able to lift a 300kg weight with a crowbar when fulcrum for the lever is 0.3m from the weight. The first man exerts his strength at 0.9m while the second is at 1.5m from the fulcrum respectively. If the men interchanged positions, they can raise a 340kg weight. What force does the first man exert? a. 40kg b. 50kg c. 60kg d. 55kg 58. Determine the reaction Rb on a simply supported beam shown in figure 3. a. 510lb b. 520lb c. 530lb d. 540lb 59. A tripod whose legs are each 4 meters long supports a load of 1000kg. The feet of the tripod are at the vertices of a horizontal equilateral triangle whose side is 3.5m. determine the load on each leg. a. 368.91kg b. 348.91kg c. 386.19kg d. 364.19kg 60. A certain cable is suspended between two supports at the same elevation and 500ft apart. The load is 500lbs per horizontal foot including the weight of the cable. The sag of the cable is 30ft. Calculate the total length of the cable. a. 503.21ft b. 504.76ft c. 505.12ft d. 506.03ft 61. The weight of a transmission cable is 1.5kg/m distributed horizontally. If the maximum safe tension of the cable is 6000kg and the allowable sag is 30m, determine the horizontal distance between the electric posts supporting the transmission cable. a. 897m b. 926m c. 967m d. 976m 62. A cable 45.4m long is carrying a uniformly distributed load along the span. If the cable is strung between two posts at the same level, 40m apart, determine the smallest value that the cable may sag. a. 7.14m b. 8.12m c. 9.71m d. 6.12m 63. A pipeline crossing a river is suspended from the steel cable stretched between two posts 120m apart. The weight of the pipe is 15kg/m while the cable weighs 1kg/m assumed to be uniformly distributed horizontally. If the allowed sag is 3m, determine the tension of the cable at the post. a. 9647.88kg b. 9476.88kg c. 9746.88kg d. 9886.47kg 64. A transmission cable is supported between two points 20m apart. The cable is loaded with a uniformly distributed load of 20kN/m throughout its span. The maximum dip of the cable is 4m. if one of the supports is 2m above the other, determine the maximum tension in the cable. a. 413.53N b. 415.53N c. 417.53N d. 419.53N 65. A transmission cable 600m long, weighing 1.5kg/m has a tension of 750 kg at each end. Find the distance between the supporting towers. a. 554.52m b. 556.89m c. 558.72m d. 559.12m 66. A man dropped a stone into a well. Four seconds later the sound of water splash is heard. Assuming sound travels at a speed of 330m/s determine how deep is the well? a. 67.12m b. 68.89m c. 69.32m d. 70.34m 67. What force is necessary to accelerate a 30,000 lb railway electric car at the rate of 1.25ft/s 2, if the force required to overcome the frictional resistance is 400lb? a. 1465.89lb b. 1564.59lb c. 1671.27lb d. 1790.02lb 68. A 3500kg car accelerates from rest. The constant forward tractive force of the car is 1000N and the constant drag force is 150N. what distance will the car travel in 3sec.? a. 0.19m b. 1.3m c. 1.1m d. 15m
69. A 50-lb crate starting from rest slides down a plane inclined at an angle of 30 o with the horizontal. If the coefficient of friction between the crate and the inclined plane is 0.3, how far will the crate move after 3 sec? a. 15.47ft b. 19.67ft c. 18.33ft d. 14.28ft 70. A skier starting from rest has just begun descending a 30 o slope. Assuming the coefficient of kinetic friction is 0.10, calculate the speed she will reach after 6 sec. a. 20m/s b. 22m/s c. 24m/s d. 18m/s 71. A projectile is fired at the top of a 30m building at an angle of 20 o with the horizontal. If the muzzle velocity of the projectile is 300m/s, how long will it take for the projectile to reach the ground? a. 20.6s b. 22.7s c. 21.2s d. 18.5s 72. A ball is thrown at an angle of 30o to the horizontal and lands on the top edge of a building 5m high. If the building is 20m away, determine the initial velocity of the ball? a. 19m/s b. 20m/s c. 21m/s d. 22m/s 73. A baseball batter hits his home run ball with a velocity of 110ft/s at an angle of 45 o above the horizontal. If the ball hits the top of a screen at the 300ft mark and bounces to the crowd, how high above the ground is the top of the screen? a. 58.5ft b. 59.1ft c. 60.5ft d. 61.8ft 74. From the top of a hill inclined at an angle of 30 o, a projectile is fired with a velocity of 50 ft/s. If the projectile is positioned perpendicular to the surface of the hill, determine its range down the hill. a. 103.52ft b. 104.65ft c. 105.89ft d. 106.7ft 75. A golf ball leaves the golf club at an angle of 60 o above the horizontal reference with a velocity of 25m/s . How high does it go? a. 23.89m b. 24.12m c. 25.90m d. 26.12m 76. A projectile with a muzzle velocity of 500m/s is fired from a gun on a top of a cliff 420 m above sea level. If the projectile hits the water surface 48 sec after being fired, determine the horizontal range of the projectile. a. 20.48km b. 21.38km c. 22.12km d. 22.58km 77. A 200 gram object attached to a 1.5m long string is whirled around a horizontal circle at a speed of 6m/s. determine the centripetal acceleration (m/s 2) of the object. a. 21 b. 22 c. 23 d. 24 78. A man keeps a 1kg toy airplane flying horizontally in a circle by holding onto a 1.5m long string attached to the wing tip. The string is always in the plane of the circular flight path. If the plane flies at 10m/s, find the tension in the string. a. 28N b. 67N c. 15N d. 18N 79. A car is moving at a speed of 25m/s around a level curve of radius 100m. What is the minimum value of the coefficient of static friction between the tires and the road required to prevent the car from skidding? a. 0.547 b. 0.346 c. 0.478 d. 0.637 80. At what angular velocity must the earth and a metal ball rotate so that the ball seems weightless? Assume radius of earth = 6370km. a. 0.0213rpm b. 0.0432rpm c. 0.0118rpm d. 0.0312rpm 81. A steel wire is 4.0m long and 2mm in diameter. How much is it elongated by a suspended body of mass 20kg? young’s modulus for steel is 196,000MPa. a. 1.123mm b. 1.385mm c. 1.374mm d. 1.274mm 82. From the figure 4 shown, determine the total elongation of the composite body carrying a tensile load of 5kN. Assume E1 = 10MPa, and E2= 15MPa. a. 118mm b. 120mm c. 112mm d. 108mm 83. A 30-m long aluminum bar is subjected to a tensile stress of 175MPa. Determine the elongation if E = 69116MPa. a. 78mm b. 76mm c. 74mm d. 72mm 84. A steel wire is 6.0m long hanging vertically, supports a load of 2000N. neglecting the weight of the wire, determine the required diameter if the stress is not to exceed 140MPa and total elongation is not to exceed 4.0mm. assumed modulus of elasticity E = 200,000MPa a. 4.37mm b. 4.26mm c. 4.45mm d. 4.16mm 85. Determine the load capacity in kN on a 25mm diameter x 1200mm long steel shaft if its maximum elongation shall not exceed 1mm. assume E = 200,000MPa a. 88.2kN b. 78.3kN c. 83.2kN d. 81.8kN o 86. An iron steam pipe is 200ft long at 0 C. What will be its increase in length when heated to 100oC? coefficient of linear expansion is 10 x 10 -6 per oC. a. 0.18ft b. 0.12ft c. 0.28ft d. 0.20ft
87. A steel railroad 10m long are laid with clearance of 3mm at a temperature of 15 oC. at what temperature will the rails just touch? If there were no initial clearance. Assume: alpha = 11.7 micro m/m deg.C and E = 200GPa a. 46.90deg.C b. 56.06deg.C c. 50.36deg.C d. 40.64deg.C 88. A cylinder of diameter 1.0cm at 30oC is to be slide into a hole on a steel plate. The hole has a diameter of 0.99970cm at 30oC. To what temperature the plate must be heated? Coefficient of linear expansion for steel is 1.2 x 10-5per oC. a. 62 b. 65 c. 48 d. 55 89. A certain steel tape is known to be 100.00ft long at a temperature of 70 oF. when the tape is at a temperature of 10oF, what tape reading corresponds to a distance of 90.00ft.? assume a coefficient of thermal expansion equal to 65 x 10 -7 per oF. a. 90.035ft b. 89.965ft c. 90.225ft d. 89.775ft 90. A 1.5cm solid shaft rotates at 1800rpm. If the allowable torsional shearing stress is 50MPa, what power in kW the said shaft can transmit? a. 5.55kW b. 6.24kW c. 6.82kW d. 8.33kW 91. How much is the maximum torque that can be applied to the end of a hollow circular shaft having an internal radius of 1.5cm and an outer radius of 2.5cm if the shear stress of the material is not to exceed 100MPa? a. 2136N.m b. 2076N.m c. 2543N.m d. 1853N.m 92. What power in kilowatts a 10mm diameter solid shaft at 30 rps can transmit if the allowable torsional shearing stress is 40MPa? a. 1.35 b. 2.20 c. 1.82 d. 1.48 93. Find the constant of an 81hp in a 3-inch cold rolled line shafting that is transmitting at 210rpm? a. 1000 b. 900 c. 950 d. 800 94. A solid shaft 2.0m long is transmitting 27N.m torque. If the shear modulus of the shaft material is 85GPa and the allowable shearing stress is 70MPa, determine the angle of twist between the two ends of the shaft. a. 1.52” b. 1.02” c. 1.44” d. 1.32” 95. Determine the maximum moment of the beam loaded as shown in figure 5. a. 1210kN.m b. 1420kN.m c. 1250kN.m d. 1120kN.m 96. A pair of force equal in magnitude, opposite in direction, and not is the same line is called _____. a. Moment b. torque c. couple d. all of the above 97. The _____ exerted by a force on a body is the measure of its effectiveness in turning the body about a certain pivot. a. Couple b. torque c. moment arm d. all of the above 98. A body is said to be in “rotational equilibrium” when: a. No net torque acts on it c. its vector sum of the forces is zero b. No net force acts on it d. the forces acting on the body are non-concurrent 99. A couple consists of two forces, ______ in magnitude, parallel and oppositely directed. a. Directly proportional c. inversely proportional b. Equal d. not equal 100. The ____ body or system is the point about with the product of the mass and moment arm sums up to zero. a. Center of gravity b. center of mass c. centerpoint d. center of gravity
