**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/m**

^{2}.

**Option B. 1 N/m**

^{2}.

**Option C. 10 Nm.**

**Correct Answer is. 1 N/m**

^{2}.

**Explanation. 1 Pa = 1 N/m**

^{2}.

**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/mm**

^{2}the minimum cross sectional area of the cable must be.

**Option A. 0.025mm**

^{2}.

**Option B. 9000mm**

^{2}.

**Option C. 40mm**

^{2}.

**Correct Answer is. 40mm**

^{2}.

**Explanation. Stress = Force/Area. Area = Force/Stress = 600/15 = 40mm**

^{2}.

**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. http://groups.physics.umn.edu/demo/old_page/demo_gifs/1R30_20.GIF**

**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. http://www.thetipsbank.com/convert.htm**

**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. http://www.bartleby.com/68/85/3685.html**

**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.**

**Explanation. http://en.wikipedia.org/wiki/Triangle**

**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/s**

^{2}).

**Option B. metre per second (m/s).**

**Option C. square metre (m**

^{2}).

**Correct Answer is. metre per second squared (m/s**

^{2}).

**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/s**

^{2}.

**Option B. 14 m/s**

^{2}.

**Option C. 252 m/s**

^{2}.

**Correct Answer is. 28 m/s**

^{2}.

**Explanation. Acceleration = change in speed / time.**

**Question Number. 5. The SI unit of velocity is the.**

**Option A. metre per second squared (m/s**

^{2}).

**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/s**

^{2}.

**Option B. 12 m/s**

^{2}.

**Option C. 8 m/s**

^{2}.

**Correct Answer is. 10 m/s**

^{2}.

**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/s**

^{2}, 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 + 1/2at**

^{2}. 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/s**

^{2}.

**Option B. 4 m/s**

^{2}.

**Option C. 2 m/s**

^{2}.

**Correct Answer is. 2 m/s**

^{2}.

**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 + 1/2at**

^{2}. 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/s**

^{2}.

**Option B. 0.981 m/s**

^{2}.

**Option C. 9.81 m/s**

^{2}.

**Correct Answer is. 9.81 m/s**

^{2}.

**Explanation. Gravity = 9.81 m/s**

^{2}.

**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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