Module 2 pAGE 5

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.

Question Number. 26. How long will it take a car moving at 60 km/hr to travel 90 km?.

Option A. 40 minutes.

Option B. 75 minutes.

Option C. 90 minutes.

Correct Answer is. 90 minutes.

Explanation. km = 1.5 * 60, therefore at 60 km/h it will take 1.5 hours = 90 mins.

Question Number. 27. An aircraft travels at 500 km/hr for 30 minutes at steady speed. How far does it move in that time?.

Option A. 500 km.

Option B. 1000 km.

Option C. 250 km.

Correct Answer is. 250 km.

Explanation. 500 km/h for 30 m/s = a distance of 250 km.

Question Number. 28. Which of the following affect the velocity of an object?.

Option A. Speed and direction.

Option B. Speed and distance.

Option C. Speed and mass.

Correct Answer is. Speed and direction.

Explanation. Velocity is a vector (it has magnitude - speed, and direction).

Question Number. 29. Acceleration involves.

Option A. change in speed or direction of movement.

Option B. change of position with time.

Option C. steady speed over a fixed period of time.

Correct Answer is. change in speed or direction of movement.

Explanation. Acceleration is a vector (it has magnitude as well as direction).

Question Number. 30. What acceleration is produced if a mass increases speed from rest to 10 ft/sec in 5 seconds?.

Option A. 2 ft/sec².

Option B. 50 ft/sec².

Option C. 0.5 ft/sec².

Correct Answer is. 2 ft/sec².

Explanation. v = u + at' where u = 0, v = 10, t = 5, so a = v/t = 10/5 = 2.

Question Number. 31. A car travelling at a speed of 5 m/s accelerates at the rate of 1 m/s2. How long will it take to reach a speed of 20 m/s?.

Option A. 15 secs.

Option B. 10 secs.

Option C. 20 secs.

Correct Answer is. 15 secs.

Explanation. The car gains 1 m/s every second, so to add 15 m/s it will take 15 seconds.

Question Number. 32. Newton’s laws of motion apply to.

Option A. solid substances only.

Option B. all substances irrespective of state.

Option C. gases and liquids only.

Correct Answer is. all substances irrespective of state.

Explanation. Newtons laws apply to solids, liquids and gases.

Question Number. 33. Which of Newton’s Laws apply most directly to an aircraft which is accelerating down a runway?.

Option A. The 3rd law.

Option B. The 2nd law.

Option C. The 1st law.

Correct Answer is. The 2nd law.

Explanation. Technically, all of Newton's laws apply but the word accelerating indicates they are looking for the second law - Force = mass x acceleration.

Question Number. 34. Which of Newton’s Laws apply most directly to a car which is slowing down due to the braking action?.

Option A. The 1st law.

Option B. The 3rd law.

Option C. The 2nd law.

Correct Answer is. The 2nd law.

Explanation. The car is decelerating therefore it is obeying the second law - Force = mass * acceleration (but technically all three laws apply).

Question Number. 35. F = ma is an equation which expresses.

Option A. Newton’s 1st law.

Option B. Newton’s 2nd law.

Option C. Newton’s 3rd law.

Correct Answer is. Newton’s 2nd law.

Explanation. Newton's second law is F = ma (Force = mass * acceleration).

Question Number. 36. What force is required to produce an acceleration of 5 m/s² on a mass of 2 kg?.

Option A. 2.5 N.

Option B. 10 N.

Option C. 50 N.

Correct Answer is. 10 N.

Explanation. F = ma = 2 * 5 = 10 Newtons (Force is measured in Newtons).

Question Number. 37. If a force of 10 lbf produces an acceleration of 2.5 ft/sec², on what mass is it acting?.

Option A. 4 slugs.

Option B. 4 lb.

Option C. 25 slugs.

Correct Answer is. 4 slugs.

Explanation. F = ma, 10 = m * 2.5, m = 10/2.5 = 4 slugs.

Question Number. 38. What is acceleration?.

Option A. Rate of change of velocity.

Option B. Rate of change of movement.

Option C. Rate of change of position.

Correct Answer is. Rate of change of velocity.

Explanation. Acceleration is rate of change of velocity.

Question Number. 39. In a gear train the driver has 100 TPI and the driven has 50 TPI.

Option A. The driven rotates twice as fast.

Option B. The driver and driven rotate at the same speed.

Option C. The driven rotates half as fast.

Correct Answer is. The driven rotates twice as fast.

Explanation. smaller wheel rotates at the faster speed (of a ratio equal to their diameters).

Question Number. 40. An aircraft of 2 metric tonnes lands with 400 kilojoules of energy, 10 kiloNewtons of force is applied at the brakes, how far does the aircraft take to stop?.

Option A. 40 M.

Option B. 400 M.

Option C. 800 M.

Correct Answer is. 40 M.

Explanation. Work done = Force * energy. Work required to convert all the kinetic energy = Force * distance. So Force * distance = 400,000 Joules. 10,000 N * distance = 400,000. Distance = 40 m.

Question Number. 41. A radar rotates 1 revolution each 30 seconds and uses 10J of energy each revolution. How many joules does it use in a day?.

Option A. 28.8 kJ.

Option B. 720 kJ.

Option C. 7200 kJ.

Correct Answer is. 28.8 kJ.

Explanation. =2 8 60 = 120 revs/hour = 120 8 24 = 2880 revs/day. 2880 8 10 = 28800 Joules = 28.8 kJ.

Question Number. 42. A light aircraft flies in a semi-circle from point A to point B. If the circle has a radius of 20km and the time taken is 30 minutes, the average speed is.

Option A. 125.7 km/h.

Option B. 110 km/h.

Option C. 80 km/h.

Correct Answer is. 125.7 km/h.

Explanation. arc distance = radius x angular distance (in rads) = 20π = 60 km (approx, taking πas 3). 60 km in 30 minutes is 120 km/h (answer is slightly more because π = 3.14, not 3.

Question Number. 43. The landing speed of an aircraft is 54 m/s². If the maximum deceleration is 3m/s² the minimum length of runway required is.

Option A. 162m.

Option B. 486m.

Option C. 360m.

Correct Answer is. 486m.

Explanation. NIL.

Question Number. 44. The number of radians in a semi circle are.

Option A. exactly 3.

Option B. π.

Option C. 2π.

Correct Answer is. π.

Explanation. full circle = 2π radians, so a semicircle = π radians = 3.142.

Question Number. 45. The angular velocity of 500 RPM is, in rads/seconds is equal to.

Option A. 1000π rads/s.

Option B. 8.33π rads/s.

Option C. 16.66π rads/s.

Correct Answer is. 16.66π rads/s.

Explanation. 500 * 2π/60 = 1000π/60 = 100π/6 = 16.66.

Question Number. 46. Which of Newton's laws relates to the formula: Force = mass * acceleration?.

Option A. 1st.

Option B. 2nd.

Option C. 3rd.

Correct Answer is. 2nd.

Explanation. Newton's Second Law F = ma.

Question Number. 47. The period of simple pendulum is.

Option A. independent of its mass.

Option B. longer for a heavy pendulum bob.

Option C. longer on the earth than on the moon.

Correct Answer is. independent of its mass.

Explanation. The only things that affect the period of a pendulum is the length (greater length = longer period) and gravity (greater gravity= shorter period).

Question Number. 48. A satellite requires 10 Joules to rotate half a revolution, which takes 30 seconds. What is the energy required for one day?.

Option A. 14,400 J.

Option B. 1,200 J.

Option C. 28,800 J.

Correct Answer is. 28,800 J.

Explanation. 10 Joules * 2revs/min * 60 mins * 24 hours.

Question Number. 49. The size of Centripetal Force on an object travelling in a circle.

Option A. increase with increasing mass of the object.

Option B. decreases with increasing speed of the object.

Option C. increases with an increasing radius of circle.

Correct Answer is. increase with increasing mass of the object.

Explanation. NIL.

Question Number. 50. For an object in circular motion at constant velocity, if the radius of its path is doubled the centripetal force will.

Option A. double.

Option B. remain the same.

Option C. half.

Correct Answer is. half.

Explanation. NIL.

Question Number. 51. An aircraft weighing 6400 pounds lands at a speed of 10 ft/Sec and stops in 10 Seconds. What force was generated by the brakes (assuming gravity as 32 ft/sec).

Option A. -2000 Lbs.

Option B. -200 Lbs.

Option C. -640 Lbs.

Correct Answer is. -200 Lbs.

Explanation. NIL.

Question Number. 52. For every action there is an equal and opposite reaction.' This is known as.

Option A. Newtons second law.

Option B. Newtons third law.

Option C. Newtons first law.

Correct Answer is. Newtons third law.

Explanation. NIL.

Question Number. 53. One radian is equal to.

Option A. the angle subtended at the centre of a circle when the arc-length formed between two radial lines is equal in length to the radius.

Option B. 66.67 degrees.

Option C. the angle subtended at the centre of a circle when the arc-length formed between two radial lines is equal to π.

Correct Answer is. the angle subtended at the centre of a circle when the arc-length formed between two radial lines is equal in length to the radius.

Explanation. NIL.

Question Number. 54. A weight on a spring almost touches the floor 7 times over 21 seconds. What is its frequency?.

Option A. 3 cycles/second.

Option B. 1/3 cycles/second.

Option C. 7 cycles/second.

Correct Answer is. 1/3 cycles/second.

Explanation. Frequency = number of oscillations divided by time = 7/21 = 1/3.

Question Number. 55. Which of the following statements describes centrifugal force?.

Option A. Equal to centripetal force and acts in the opposite direction.

Option B. Greater than centripetal force and acts in the opposite direction.

Option C. Smaller than centripetal force and acts in the opposite direction.

Correct Answer is. Greater than centripetal force and acts in the opposite direction.

Explanation. Centrifugal is away from centre and equal (but opposite) to centripetal force.

Question Number. 56. A body starting from rest accelerates at the rate of 20 metres per second squared. What is the distance covered until the body reaches a velocity of 50 metres per second?.

Option A. 0.625 kilometres.

Option B. 50 metres.

Option C. 62.5 metres.

Correct Answer is. 62.5 metres.

Explanation. NIL.

Question Number. 57. The oscillation produced by a pendulum 2500mm long has a periodic time of.

Option A. 300 milliseconds.

Option B. 3 seconds.

Option C. 1.25 seconds.

Correct Answer is. 3 seconds.

Explanation. T = 2xπ√L/g = √2.5/10 = 6 * √0.25 = 6 * 0.5 = 3.

Question Number. 58. A drive shaft has a speed 150π radians a second. What is the speed in RPM?.

Option A. 4500.

Option B. 9000.

Option C. 1500.

Correct Answer is. 4500.

Explanation. 150π * 60/2π = 4500

2.3a. Mechanics – Dynamics.

Question Number. 1. As an object slides down a slope, its.

Option A. kinetic energy increases and its potential energy increases.

Option B. kinetic energy increases and its potential energy decreases.

Option C. kinetic energy decreases and its potential energy increases.

Correct Answer is. kinetic energy increases and its potential energy decreases.

Explanation. Potential energy is converted into kinetic energy.

Question Number. 2. A single fixed pulley (discounting friction etc) has a mechanical advantage of.

Option A. 2.

Option B. 1/2.

Option C. 1.

Correct Answer is. 1.

Explanation. NIL.

Question Number. 3. What is the ratio of load to effort called?.

Option A. Mechanical advantage.

Option B. Velocity ratio.

Option C. Mechanical ratio.

Correct Answer is. Mechanical advantage.

Explanation. NIL.

Question Number. 4. 1 kW is.

Option A. 3413 BTU per hour.

Option B. 1.56 HP.

Option C. 360 Joules.

Correct Answer is. 3413 BTU per hour.

Explanation. 1 BTU = 0.293 W. 1 W = 1/0.293 BTU = 3.413 BTU. 1 kW = 3413 BTU.

Question Number. 5. The tension in the cable of a crane is 2500 N and it lifts a load through 50m, what is the work done on the load?.

Option A. 1.25 * 10 J5.

Option B. 500 J.

Option C. 12.5 kJ.

Correct Answer is. 1.25 * 10 J5.

Explanation. NIL.

Question Number. 6. What is the kinetic energy of an aircraft of mass of 2 metric tonnes and has a velocity of 2m/s?.

Option A. 8 kJ.

Option B. 4 kJ.

Option C. 2 kJ.

Correct Answer is. 4 kJ.

Explanation. Kinetic energy = 1/2mV. Only the V is squared. 2 metric tonnes = 2000 kg.

Question Number. 7. The work done in lifting a mass of 2000 kg vertically to a height of 40 metres is.

Option A. 80 kJ.

Option B. 784.8 kJ.

Option C. 500 kJ.

Correct Answer is. 784.8 kJ.

Explanation. Work done = Force * distance (force = mass * gravity). Wd = 2000 * 10 * 40 = 800,000 approx. (answer is slightly less because g = 9.81, not 10).

Question Number. 8. If a machine has a mechanical advantage of 10 and a velocity ratio of 20. The efficiency of the machine is.

Option A. 200%.

Option B. 0.5.

Option C. 2.

Correct Answer is. 0.5.

Explanation. 10 times the force out and only 1/20th speed, it must have an efficiency of a 1/2. (100% efficient it would have 10 times the force and 1/10th the speed - straight trade of force for speed).

Question Number. 9. 1 Watt =.

Option A. 1kg/h.

Option B. 1 Joule/s.

Option C. 1 HP.

Correct Answer is. 1 Joule/s.

Explanation. 1 Watt = 1 Joule/second.

Question Number. 10. How would you work out the work done by a machine assuming it is 100% efficient?.

Option A. Input and output.

Option B. Mechanical advantage and output.

Option C. Mechanical advantage and input.

Correct Answer is. Mechanical advantage and input.

Explanation. Assuming the 'input' means input force, to calculate the work done you will need the input force and the mechanical advantage of the machine to calculate the output force and distance (Work done = force * distance of output).

Question Number. 11. Ignoring friction, if you let an object slide down a slope, at the bottom.

Option A. the potential energy is equal to the kinetic energy.

Option B. the potential energy is more than the kinetic energy.

Option C. the kinetic energy is more than the potential energy.

Correct Answer is. the kinetic energy is more than the potential energy.

Explanation. All potential energy is converted to kinetic energy.

Question Number. 12. 1 HP = 33000 ft.lbs/min or 500 ft.lbs/s or.

Option A. 736 Watts.

Option B. 746 Watts.

Option C. 1360 Watts.

Correct Answer is. 746 Watts.

Explanation. 1 HP = 746 Watts.

Question Number. 13. A force of 15N is needed to move a body of mass 30kg along a footpath with uniform velocity. Find the coefficient of dynamic friction.(take g as 10m/s/s).

Option A. 1/20.

Option B. 1/2.

Option C. 20.

Correct Answer is. 1/20.

Explanation. NIL.

Question Number. 14. A mass of 400kg moves 27 metres with a force of 54N. What is the work produced?.

Option A. 10.1kJ.

Option B. 583.2kJ.

Option C. 1458J.

Correct Answer is. 1458J.

Explanation. NIL.

Question Number. 15. The SI unit of Power is the.

Option A. Volt.

Option B. Pascal.

Option C. Watt.

Correct Answer is. Watt.

Explanation. NIL.

Question Number. 16. What is 1 joule in calories?.

Option A. 4.186.

Option B. 252.

Option C. 0.239.

Correct Answer is. 0.239.

Explanation. NIL.

Question Number. 17. If you push an object with a force of 5 N for 10 m in 4 seconds, how much power is used?.

Option A. 12.5 watts.

Option B. 8 watts.

Option C. 200 Watts.

Correct Answer is. 12.5 watts.

Explanation. NIL.

Question Number. 18. What is the Kinetic Energy of a 2 kg object moving at a velocity of 12 m/s?.

Option A. 24 Joules.

Option B. 288 Joules.

Option C. 144 Joules.

Correct Answer is. 144 Joules.

Explanation. NIL.

Question Number. 19. A mass of 3kg weighs approximately.

Option A. 0.675 N.

Option B. 6.6 LB.

Option C. 1.3 LB.

Correct Answer is. 6.6 LB.

Explanation. 1 kg = 2.2 lb. So 3 kg = 3 * 2.2 = 6.6 lb.

Question Number. 20. Power is the rate of doing work. It is measured in.

Option A. Watts/Seconds.

Option B. Joules/Seconds.

Option C. Joules * Seconds.

Correct Answer is. Joules/Seconds.

Explanation. NIL.

Question Number. 21. A 6000 kg engine is lifted off a wing to a height 0.5 metres and then pushed across the hangar 24 meters. The force required to push the trolley is 12 kN. What is the work done to move the trolley?.

Option A. 298kJ.

Option B. 84MJ.

Option C. 288kJ.

Correct Answer is. 288kJ.

Explanation. NIL.

Question Number. 22. A ball is dropped from rest. What is its speed after 4 seconds? (Take g as 10m/s/s).

Option A. 80m/s.

Option B. 40m/s.

Option C. 20m/s.

Correct Answer is. 40m/s.

Explanation. NIL.

Question Number. 23. 1 KW is equal to.

Option A. 1.34 HP.

Option B. 1000 Joules.

Option C. 252 BTU.

Correct Answer is. 1.34 HP.

Explanation. NIL.

Question Number. 24. Ten kilograms is expressed numerically as.

Option A. 1 Mg.

Option B. 10 K.

Option C. 10 kg.

Correct Answer is. 10 kg.

Explanation. 10 kilograms = 10 kg.

Question Number. 25. An object accelerating down a slope would gain kinetic energy.

Option A. less than the potential energy lost.

Option B. greater than the potential energy lost.

Option C. equal to the potential energy lost.

Correct Answer is. equal to the potential energy lost.

Explanation. NIL.