Module 2 Page 4

Question Number. 51. What atmospheric conditions will cause the true landing speed of an aircraft to be highest?.
Option A. Low temp, high humidity.
Option B. Head wind, low humidity.
Option C. High temp, high humidity.
Correct Answer is. High temp, high humidity.
Explanation. Lift is least at low density. Density is lowest at high temperature and high humidity.

Question Number. 52. Structures designed to withstand compression are called a.
Option A. tie.
Option B. strut.
Option C. beam.
Correct Answer is. strut.
Explanation. Tension - Tie, Compression - Strut, Bending - Beam.

Question Number. 53. 1 Pascal equals.
Option A. 105 N/m2.
Option B. 1 N/m2.
Option C. 10 Nm.
Correct Answer is. 1 N/m2.
Explanation. 1 Pa = 1 N/m2.

Question Number. 54. The addition of 2 different vectors to produce another vector is called.
Option A. component.
Option B. resolution.
Option C. resultant.
Correct Answer is. resultant.
Explanation. The resultant of two vectors. The mathematical process is actually called 'composition'.

Question Number. 55. Two items weighing 11kg and 8kg are placed 2m and 1m respectively aft of the C of G of an aircraft. How far forward of the C of G must a weight of 30kg be placed so as not to change the C of G?.
Option A. 2m.
Option B. 1.5m.
Option C. 1m.
Correct Answer is. 1m.
Explanation. Total moment = (11*2) + (8*1) = 30kgm. The 30 kg mass must be placed such that 30kg * Xm = 30 kg m. Hence X = 1m.

Question Number. 56. A point at which the total force of a body acts is known as the.
Option A. centre of gravity.
Option B. point of equilibrium.
Option C. centre of mass.
Correct Answer is. centre of gravity.
Explanation. If by force they mean 'weight' then it is Centre of Gravity.

Question Number. 57. A load of 600N is suspended by a cable. If the stress in the cable is said to be limited to 15N/mm2 the minimum cross sectional area of the cable must be.
Option A. 0.025mm2.
Option B. 9000mm2.
Option C. 40mm2.
Correct Answer is. 40mm2.
Explanation. Stress = Force/Area. Area = Force/Stress = 600/15 = 40mm2.

Question Number. 58. A spring, operating within its elastic range, shortens by 60mm when a load of 480N is applied to it. Calculate the total shortening when the load is increased by 120N.
Option A. 82mm.
Option B. 45mm.
Option C. 75mm.
Correct Answer is. 75mm.
Explanation. 600/480 * 60 = 75mm.

Question Number. 59. The c.g. of a triangular plate is at the intersection of.
Option A. medians from a vertex to the opposite side.
Option B. angle bisectors.
Option C. perpendicular bisectors.
Correct Answer is. medians from a vertex to the opposite side.
Explanation. NIL.

Question Number. 60. When a square block of material is pushed into a parallelogram, the material is under what stress type?.
Option A. Compression.
Option B. Torsion.
Option C. Shear.
Correct Answer is. Shear.
Explanation. NIL.

Question Number. 61. A quantity which has size but no direction is called a.
Option A. Scalar.
Option B. Moment.
Option C. Vector.
Correct Answer is. Scalar.
Explanation. scalar has size only (mass, area etc.). A vector has size and direction (velocity, force etc.).

Question Number. 62. The advantage of using a machine is.
Option A. mechanical advantage of input.
Option B. mechanical advantage of output.
Option C. input work is less than the output work.
Correct Answer is. mechanical advantage of output.
Explanation. Mechanical advantage is usually on the outp.

Question Number. 63. Which of the following can transmit pressure?.
Option A. Liquids and gases.
Option B. Solids and gases.
Option C. Any matter can transmit pressure, depending on temperature.
Correct Answer is. Liquids and gases.
Explanation. NIL.

Question Number. 64. A moment is created by a force of 5N acting 4m from the pivot on a uniform bar. At what distance must a force of 10N be applied to balance the beam?.
Option A. 8 m.
Option B. 4 m.
Option C. 2 m.
Correct Answer is. 2 m.
Explanation. 5 * 4 = 20, 10 * X = 20 X = 2m.

Question Number. 65. A lever of length 105 cm is used with a fulcrum placed 15 cm from the end bearing the load. Its mechanical advantage is.
Option A. 1/6.
Option B. 7.
Option C. 6.
Correct Answer is. 6.
Explanation. The TOTAL length is 105 cm, so the input end is 90 cms. 90/15 = 6.

Question Number. 66. The stress created when a material is pulled apart is called.
Option A. tension.
Option B. torsion.
Option C. compression.
Correct Answer is. tension.
Explanation. NIL.

Question Number. 67. The yield point of a material is the point at which.
Option A. strain becomes proportional to stress.
Option B. the material ruptures or breaks.
Option C. permanent deformation takes place.
Correct Answer is. permanent deformation takes place.
Explanation. NIL.

Question Number. 68. Assuming constant temperature. If a steel bar of length 2 m deforms to a length of 2.2 m under applied load. The strain is.
Option A. 1.1.
Option B. 0.9.
Option C. 0.1.
Correct Answer is. 0.1.
Explanation. Strain = Extension/Original Length = 0.2/2 = 0.1.

Question Number. 69. A Scalar quantity has.
Option A. sense, magnitude and direction.
Option B. sense and direction.
Option C. magnitude only.
Correct Answer is. magnitude only.
Explanation. NIL.

Question Number. 70. A hydraulic piston of 2.5 square inches produces 7500lbf, What pressure is used?.
Option A. 5000 PSI.
Option B. 3000 PSI.
Option C. 7000 PSI.
Correct Answer is. 3000 PSI.
Explanation. Pressure = Force/Area.

Question Number. 71. Forces passing through a common point are said to be.
Option A. coherent.
Option B. coplanar.
Option C. concurrent.
Correct Answer is. concurrent.
Explanation. NIL.

Question Number. 72. A force of 5 Newtons acting perpendicularly at 300 centimetres from the pivot produces a moment of.
Option A. 1500 Newton metre.
Option B. 15 Newton metre.
Option C. 1.5 Kilonewton millimetre.
Correct Answer is. 15 Newton metre.
Explanation. 3m * 5N = 15 Nm.

Question Number. 73. Equilibrium of translation occurs when.
Option A. downward forces equal upward (reactive) forces.
Option B. clockwise moments equal counterclockwise moments.
Option C. clockwise forces and counterclockwise forces are equal.
Correct Answer is. downward forces equal upward (reactive) forces.
Explanation. Translation is linear movement.

Question Number. 74. The conversion factor to convert litres to pints is.
Option A. 0.57.
Option B. 1.76.
Option C. 2.2.
Correct Answer is. 1.76.
Explanation. NIL.

Question Number. 75. Hydraulic pressure can be restored by.
Option A. the use of pressure/heat exchange.
Option B. compressing the air charge in an accumulator.
Option C. compressing the fluid in a reservoir.
Correct Answer is. compressing the air charge in an accumulator.
Explanation. NIL.

Question Number. 76. When checking a hydraulic accumulator initial air pressure, the hydraulic system pressure.
Option A. should be at the normal working pressure.
Option B. is not important.
Option C. should be released.
Correct Answer is. should be released.
Explanation. NIL.

Question Number. 77. One kg is the mass of.
Option A. one litre of pure water.
Option B. one pint of pure water.
Option C. one gallon of pure water.
Correct Answer is. one litre of pure water.
Explanation. NIL.

Question Number. 78. The centre of gravity of a triangle is.
Option A. 1/3 the median from the base.
Option B. 1/3 the bisector from the base.
Option C. 1/3 the height from the base.
Correct Answer is. 1/3 the median from the base.

Question Number. 79. A lifting machine moves with an effort, a distance of 200 cm, in order to raise it 0.5 m. The Velocity Ratio is.
Option A. 0.25.
Option B. 4.
Option C. 40.
Correct Answer is. 4.
Explanation. Distance ratio input/ output = 2/0.5 = 4. Velocity ratio is same as Distance ration.

Question Number. 80. Two Vectors are at 90 degrees to each other having magnitudes of 3N and 4N. The resultant is.
Option A. 5N.
Option B. 1N.
Option C. 7N.
Correct Answer is. 5N.
Explanation. Vectors make a 3-4-5 triangle.

Question Number. 81. Which of the following has no units?.
Option A. Strain.
Option B. Stress.
Option C. Elasticity.
Correct Answer is. Strain.
Explanation. NIL.

2.2. Mechanics – Kinetics.

Question Number. 1. For a car weighing 1000 N, what force would be required to accelerate the car to 3 ms-2.
Option A. 3270 N.
Option B. 305.8 N.
Option C. 3000 N.
Correct Answer is. 305.8 N.
Explanation. F = ma F = 1000/9.81 * 3 F = 305.8 N (The 'divide by' 9.81 is necessary to convert the 1000 N into a mass (in kg)).

Question Number. 2. A time period of 10 microseconds is equal to a frequency of.
Option A. 100 kHz.
Option B. 10 kHz.
Option C. 1 Mhz.
Correct Answer is. 100 kHz.
Explanation. Frequency = 1/time period. 1/0.00001 = 100,000 = 100 kHz.

Question Number. 3. The SI unit of acceleration is the.
Option A. metre per second squared (m/s2).
Option B. metre per second (m/s).
Option C. square metre (m2).
Correct Answer is. metre per second squared (m/s2).
Explanation. NIL.

Question Number. 4. If a body starts at rest and reaches 84 m/s in 3 seconds, its acceleration is.
Option A. 28 m/s2.
Option B. 14 m/s2.
Option C. 252 m/s2.
Correct Answer is. 28 m/s2.
Explanation. Acceleration = change in speed / time.

Question Number. 5. The SI unit of velocity is the.
Option A. metre per second squared (m/s2).
Option B. metre per second (m/s).
Option C. metre (m).
Correct Answer is. metre per second (m/s).
Explanation. NIL.

Question Number. 6. An aircraft flies 1350 nmiles in 2h 15mins. What is the average speed?.
Option A. 600 nmiles/hour.
Option B. 600 miles/hour.
Option C. 150 nmiles/hour.
Correct Answer is. 600 nmiles/hour.
Explanation. Average speed = distance/time = 1350/2.25 = 600 nm/h.

Question Number. 7. A spring extends 7 cm to the ground and back again 20 times a minute. What is the period?.
Option A. 7 cm.
Option B. 3 seconds.
Option C. 1/3 cycle.
Correct Answer is. 3 seconds.
Explanation. Frequency = 20/60 = 1/3 Hz. Time period = 1/f = 3 seconds.

Question Number. 8. A cyclist goes from rest to 50 m/s in 5 seconds. What is the average acceleration?.
Option A. 10 m/s2.
Option B. 12 m/s2.
Option C. 8 m/s2.
Correct Answer is. 10 m/s2.
Explanation. Acceleration = change in speed / time.

Question Number. 9. What is the period of a frequency of 4 Hz?.
Option A. 8 seconds.
Option B. 0.25 seconds.
Option C. 4 seconds.
Correct Answer is. 0.25 seconds.
Explanation. Period = 1/f.

Question Number. 10. A dot rotates around the circumference of a circle. If the vertical position of this dot is plotted on a graph with respect to time the result will be.
Option A. a linear motion.
Option B. a transverse waveform.
Option C. a sinusoidal waveform.
Correct Answer is. a sinusoidal waveform.
Explanation. This is why an AC generator produces a sine wave frequency.

Question Number. 11. A freely falling body, falling from a height of 2km, and assuming g = 10m/s2, will strike the ground in a time of.
Option A. 400s.
Option B. 80s.
Option C. 20s.
Correct Answer is. 20s.
Explanation. From the equations of motion s = ut + 1/2at2. If it starts at rest u (and hence ut) is zero. Use s = 2000 m, plug in the numbers and transpose for t.

Question Number. 12. What is the angular velocity of a shaft rotating at 300rpm in radians/second?.
Option A. 10π radians/second.
Option B. 2π radians/second.
Option C. 5π radians/second.
Correct Answer is. 10π radians/second.
Explanation. velocity = 2π(RPM)/60 = 2π * 300/60 = 10π radians/second.

Question Number. 13. The force that acts on a body to cause it to rotate in a circular path is called the.
Option A. centripetal force.
Option B. centrifugal force.
Option C. inertia force.
Correct Answer is. centripetal force.
Explanation. Centripetal' force is the force pulling the rotating object towards the centre of rotation. 'Centrifugal' force is the equal and opposite reaction.

Question Number. 14. An aircraft of 2 metric tonnes uses 800 kilojoules kinetic energy to make an emergency stop. Its brakes apply a force of 10 kiloNewtons. What distance does it travel before it comes to a stop?.
Option A. 40m.
Option B. 800m.
Option C. 80m.
Correct Answer is. 80m.
Explanation. Energy = Force * Distance. 800,000J = 10,000N x Distance. Distance = ??.

Question Number. 15. A body rotating at an angular velocity of 5 radians/sec, with a radius of 5 metres has a speed of.
Option A. 5π metres per second.
Option B. 5 metres per second.
Option C. 25 metres per second.
Correct Answer is. 25 metres per second.
Explanation. velocity = Radius * Omega (Omega = radians/sec). V = 5 * 5 = 25 m/s.

Question Number. 16. A mass of 400 kg moves 27metres, with a force of 54N, what is the work produced?.
Option A. 1458 J.
Option B. 583.2 KJ.
Option C. 10.1 KJ.
Correct Answer is. 1458 J.
Explanation. Work = Force x Distance = 54 * 27 = 1458 J. It is not moving under gravity so the 400 kg is a red herring.

Question Number. 17. A mass on a spring nearly hits the ground 20 times a minute, its frequency is.
Option A. 3 cycles per second.
Option B. 1/3 cycle per second.
Option C. 20 cycles per second.
Correct Answer is. 1/3 cycle per second.
Explanation. cycles per minute = 20/60 cycles per second = 2/6 = 1/3 cycle per second.

Question Number. 18. A body travelling at 20 m/s accelerates to 36 m/s in 8 seconds, what is its acceleration?.
Option A. 8 m/s2.
Option B. 4 m/s2.
Option C. 2 m/s2.
Correct Answer is. 2 m/s2.
Explanation. V = u +at 36 = 20 + 8a 36-20 = 8a 16/8 = a.

Question Number. 19. A body dropped from 10 m will hit the ground in.
Option A. 2 seconds.
Option B. 0.2 seconds.
Option C. 1.41 second.
Correct Answer is. 1.41 second.
Explanation. s = ut + 1/2at2. Take s = 10, u = 0, a = g = 10. Calculate t. (Remember that 0 * t = 0).

Question Number. 20. What is the rate of gravity?.
Option A. 12.7 m/s2.
Option B. 0.981 m/s2.
Option C. 9.81 m/s2.
Correct Answer is. 9.81 m/s2.
Explanation. Gravity = 9.81 m/s2.

Question Number. 21. An object travels 18 km in 1 minute 30 seconds. What is its average speed?.
Option A. 200 m/s.
Option B. 270 m/s.
Option C. 100 ms.
Correct Answer is. 200 m/s.
Explanation. Average speed = distance/time = 18000 metres / 90 seconds = 200 m/s.

Question Number. 22. 100 m is approximately.
Option A. 220 yards.
Option B. 109 yards.
Option C. 66 yards.
Correct Answer is. 109 yards.
Explanation. m = 3.3 ft. 100 m = 330 ft. 3 ft = 1 yd so 330/3 = 110 yards.

Question Number. 23. A car moves over a distance of 5 miles at steady speed in 10 minutes. What is the speed?.
Option A. 30 mph.
Option B. 15 mph.
Option C. 60 mph.
Correct Answer is. 30 mph.
Explanation. in 10 mins, 10 miles in 20 mins, 15 miles in 30 mins, 30 miles in 1 hr.

Question Number. 24. A spaceship travels a distance of 480,000 miles in 2 days. What is its speed?.
Option A. 48,000 mph.
Option B. 36,000 mph.
Option C. 10,000 mph.
Correct Answer is. 10,000 mph.
Explanation. 480,000/48 = 10,000 MPH.

Question Number. 25. A cyclist covers a distance of 1,000 m at a constant speed in 90 seconds, What is his speed?.
Option A. 50 m/s.
Option B. 12.5 m/s.
Option C. 11.1 m/s.
Correct Answer is. 11.1 m/s.
Explanation. 1000m/90secs = 11.1 m/s

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