2.1.
Mechanics – Statics.
Question
Number. 1. An insulator has its electrons.
Option A.
tightly bound.
Option B.
loosely bound.
Option C.
otally free from the atoms.
Correct
Answer is. tightly bound.
Explanation.
Aircraft Electricity & Electronics 5th edition TK Eismin.
Question
Number. 2. The centre of gravity of an aircraft is adjusted by two
weights, 10 kg and 5 ckg plaed 4m and 2 m aft of the c of g. To what
position must a 20 kg weight be added to balance the c of g?.
Option A.
2.5m.
Option B.
4m.
Option C.
2m.
Correct
Answer is. 2.5m.
Explanation.
(10 * 4) + (5 * 2) = 20 x ? 40+10=20 x ? ? = 2.5m.
Question
Number. 3. For the CGS system, the force is.
Option
A. the 'N' which produces an acceration of 1 cm/s2 for
a mass of gram.
Option
B. the 'dyne' which produces an acceleration of 1cm/s2 for
a mass of gram.
Option
C. the 'pd1' which produces an acceleration of 1 cm/s2 for
a mass of gram.
Correct
Answer is. the 'dyne' which produces an acceleration of 1cm/ s2 for
a mass of gram.
Explanation.
NIL.
Question
Number. 4. The quadrature component of a vector is.
Option A.
45° to the original.
Option B.
90° to the original.
Option C.
180° to the original.
Correct
Answer is. 90° to the original.
Explanation.
NIL.
Question
Number. 5. 1 Newton is equal to.
Option A.
1 kilogram meter per second per second.
Option B.
1 kilogram of force.
Option C.
1 joule per second.
Correct
Answer is. 1 kilogram meter per second per second.
Explanation.
Remember Newtons 2nd law 'F=ma'. Well, 'm' is in kilograms, 'a' is in
metres per second squared (or meters per second per second) so put
the two together and 'F' is….
Question
Number. 6. The SI unit of mass is the.
Option A.
metre (m).
Option B.
pound (lb).
Option C.
kilogram (kg).
Correct
Answer is. kilogram (kg).
Explanation.
NIL.
Question
Number. 7. A slug is a unit of.
Option A.
speed.
Option B.
mass.
Option C.
weight.
Correct
Answer is. mass.
Explanation.
A very old unit of mass - equal to 14.6 kg.
Question
Number. 8. If an object in air is submerged in a liquid or a gas its
weight will.
Option A.
increase.
Option B.
decrease.
Option C.
remain the same.
Correct
Answer is. remain the same.
Explanation.
thing that can change the weight of an object is the gravitational
field it is in.
Question
Number. 9. If a material is loaded excessively and is permanently
deformed, it is said to be.
Option A.
stretched.
Option B.
stressed.
Option C.
strained.
Correct
Answer is. strained.
Explanation.
Strain = extension / original length (Stress = force / area).
Question
Number. 10. The SI unit of force is the.
Option A.
Newton (N).
Option B.
Metre (m).
Option C.
Pascal (Pa).
Correct
Answer is. Newton (N).
Explanation.
NIL.
Question
Number. 11. The formula for calculating stress is.
Option A.
load divided by cross sectional area.
Option B.
area divided by load.
Option C.
load multiplied by cross sectional area.
Correct
Answer is. load divided by cross sectional area.
Explanation.
NIL.
Question
Number. 12. Stress is given by.
Option A.
force per unit area.
Option B.
extension per original length.
Option C.
force per original length.
Correct
Answer is. force per unit area.
Explanation.
NIL.
Question
Number. 13. The force which opposes twisting deformation is.
Option A.
torsion.
Option B.
strain.
Option C.
shear.
Correct
Answer is. torsion.
Explanation.
A torsional force opposes twisting.
Question
Number. 14. A force perpendicular to a beam produces what type of
stress?.
Option A.
compressive.
Option B.
shear.
Option C.
tensile.
Correct
Answer is. shear.
Explanation.
perpendicular to a beam (such a s a man on a diving board) produces
bending and shear stress.
Question
Number. 15. The extension of a spring can be determined using.
Option A.
Charles' Law.
Option B.
Newton's 2nd Law.
Option C.
Hooke's Law.
Correct
Answer is. Hooke's Law.
Explanation.
Hooke's law is 'extension is proportional to force'.
Question
Number. 16. When a steel bar is overstressed, what is the name of the
point at which it does not return to its original form after the load
is released?.
Option A.
Ultimate point.
Option B.
Yield point.
Option C.
Young's modulus.
Correct
Answer is. Yield point.
Explanation.
NIL.
Question
Number. 17. Two couples with magnitude F act against each other. The
resultant will be.
Option A.
-2F.
Option B.
2F.
Option C.
0.
Correct
Answer is. 0.
Explanation.
A 'couple' is 2 forces acting in the same rotational direction an
equal distance from a pivot point (like turning a die holder). Two
couples in opposition will cancel each other.
Question
Number. 18. The height of mercury required to give 1 bar is.
Option A.
700 mm.
Option B.
1000 mm.
Option C.
760 mm.
Correct
Answer is. 760 mm.
Explanation.
1 bar is almost atmospheric pressure.
Question
Number. 19. A vessel has 25 ml of water which produces 10 kPa. If
another 125 ml of water is added, what will be the pressure in the
vessel?.
Option A.
40 kPa.
Option B.
50 kPa.
Option C.
60 kPa.
Correct
Answer is. 60 kPa.
Explanation.
pressure = density * gravity * height. 25ml + 125ml = 150ml or 6
times. So 6 * height = 6 * pressure.
Question
Number. 20. Two hydraulic jacks with different diameters have the
same fluid pressures entering at the same rate. They will extend at.
Option A.
the same rate until the smaller jack becomes full.
Option B.
the same rate.
Option C.
different rates.
Correct
Answer is. different rates.
Explanation.
diameter will have the greater force. The 'trade-off' for this is
that it will move slower.
Question
Number. 21. What load can be lifted on jack B?.
Option A.
300N.
Option B.
200N.
Option C.
100N.
Correct
Answer is. 100N.
Explanation.
10 times the area, then it can lift 10 times the load.
Question
Number. 22. The most common method of expressing pressure is in.
Option A.
inch pounds per square inch.
Option B.
grams per square inch.
Option C.
pounds per square inch.
Correct
Answer is. pounds per square inch.
Explanation.
Pressure is usually measured in Pounds per Square Inch (PSI).
Question
Number. 23. The difference between two pressures is.
Option A.
vacuum pressure.
Option B.
differential pressure.
Option C.
static pressure.
Correct
Answer is. differential pressure.
Explanation.
Differential pressure is the difference between two pressures (such
as inside and outside the aircraft cabin).
Question
Number. 24. What torque loading would you apply to a nut if the force
is 50 lbs, exerted 2 feet from its axis?.
Option A.
100 lbs.ft.
Option B.
600 lbs.ft.
Option C.
251 lbs.ft.
Correct
Answer is. 100 lbs.ft.
Explanation.
Torque loading = force * distance.
Question
Number. 25. In a jack with a ram only on one side and hydraulic fluid
applied from both sides.
Option A.
a condition of hydraulic lock exists and no movement will take place.
Option B.
the ram will move opposite to the side where the ram is due to
pressure acting on differential areas.
Option C.
the ram will move to the side where the ram is, due to pressure
acting on differential areas.
Correct
Answer is. the ram will move opposite to the side where the ram is
due to pressure acting on differential areas.
Explanation.
The non-ram side has a greater area, so the ram will be pushed from
that side to the ram side.
Question
Number. 26. Using the same hydraulic pressure, the force applied by a
hydraulic jack of 4 sq. inch piston area.
Option A.
will be half that applied by a similar jack of 2 sq. inch piston
area.
Option B.
will be equal to that applied by a similar jack of 2 sq. inch piston
area.
Option C.
will be twice that applied by a similar jack of 2 sq. inch piston
area.
Correct
Answer is. will be equal to that applied by a similar jack of 2 sq.
inch piston area.
Explanation.
Force = pressure * area.
Question
Number. 27. A pressure of 100 PSI acts on two jacks in a hydraulic
system, having piston areas 2 sq in and 4 sq in.
Option A.
the smaller jack will exert a force of 50 lb and the larger a force
of 25 lb.
Option B.
the smaller jack will exert a force of 200 lb and the larger a force
of 400 lb.
Option C.
the two jacks will exert the same force.
Correct
Answer is. the smaller jack will exert a force of 200 lb and the
larger a force of 400 lb.
Explanation.
Force = pressure * area. 100 * 2 = 200 lbs. 100 * 4 = 400 lbs.
Question
Number. 28. The purpose of an accumulator in a hydraulic system is
to.
Option A.
collect air from the hydraulic fluid, thus reducing the requirement
for frequent bleeding.
Option B.
relieve excess pressure.
Option C.
store hydraulic fluid under pressure.
Correct
Answer is. store hydraulic fluid under pressure.
Explanation.
An accumulator stores hydraulic pressure for use when the main
pressure pump fails.
Question
Number. 29. If the hydraulic system accumulator has a low air
pressure, it will cause.
Option A.
rapid pressure fluctuations during operation of services.
Option B.
rapid movement of the operating jacks.
Option C.
slow build up of pressure in the system.
Correct
Answer is. rapid pressure fluctuations during operation of services.
Explanation.
The secondary purpose of an accumulator is to damp out pressure
fluctuations.
Question
Number. 30. The specific torque loading for a bolt is 50 lbs.ins but
an extension of 2 inches is needed to reach the bolt in addition to
the 8 inches torque wrench. What will the actual reading?.
Option A.
54 lb.ins.
Option B.
40 lb.ins.
Option C.
60 lb.ins.
Correct
Answer is. 40 lb.ins.
Explanation.
New torque reading = desired torque x L/(x+L). 50 * 8/10 = 40 lb.ins.
Question
Number. 31. If 1500 psi hydraulic pressure is pumped into an
accumulator, with a pre-charge air pressure of 1000 psi the gauge
will read.
Option A.
2500 psi.
Option B.
1500 psi.
Option C.
1000 psi.
Correct
Answer is. 1500 psi.
Explanation.
The accumulator pressure gauge reads the hydraulic pressure only when
it is above the charge pressure.
Question
Number. 32. Young's modulus is.
Option A.
stress * strain.
Option B.
strain / stress.
Option C.
stress / strain.
Correct
Answer is. stress / strain.
Explanation.
Young's Modulus (E) is the ratio Stress / Strain.
Question
Number. 33. A cylinder filled with water to half a metre will exert a
pressure of.
Option A.
4.9 Pa.
Option B.
4900 Pa.
Option C.
49 Pa.
Correct
Answer is. 4900 Pa.
Explanation.
Pressure = density * gravity * height = 1000 (for water) * 10 * 0.5 =
5000 Pa. Answer is 4900 Pa because gravity is slightly less than 10
(9.81 to be exact).
Question
Number. 34. A mass of 10kg placed 2 metres away from a pivot will
have a moment of.
Option A.
196 NM.
Option B.
50 NM.
Option C.
20 NM.
Correct
Answer is. 196 NM.
Explanation.
10 kg = 10 * 9.8 = 98N. Moment = force * radius = 98 * 2 = 196 Nm.
Question
Number. 35. 25 litres of fuel exerts a pressure of 10KPa. If a
further 125 litres is added, the pressure will now be.
Option A.
50 kPa.
Option B.
60 kPa.
Option C.
40 kPa.
Correct
Answer is. 60 kPa.
Explanation.
Total Fuel = 150 litres = 6 * 25. 6 * original pressure = 60 kPa.
Question
Number. 36. 1000 lb/in2 is
in an accumulator. If 3000 lb/in2 of
hydraulic fluid is pumped in, what is the pressure on the air side?.
Option
A. 3000 lb/in2.
Option
B. 4000 lb/in2.
Option
C. 1000 lb/in2.
Correct
Answer is. 3000 lb/in2.
Explanation.
The piston does not move until the hydraulic pressure exceeds 1000
psi. From then on, the air and hydraulic pressures are equal (at all
times that the piston is off its stops).
Question
Number. 37. A fractional decrease in volume of a material when it is
compressed is a function of the.
Option A.
compressive strain.
Option B.
compressive strain.
Option C.
bulk modulus.
Correct
Answer is. bulk modulus.
Explanation.
Bulk modulus = ratio of change in pressure to the fractional volume
compression.
Question
Number. 38. A ram has a piston with 2 in2.
Another ram with a piston of 4 in2 will
provide.
Option A.
the same force.
Option B.
double the force.
Option C.
square the force.
Correct
Answer is. double the force.
Explanation.
Double the area = double the force. (However, if the question said
double the radius or diameter, the force is a square of that, i.e
4x).
Question
Number. 39. How much force is exerted by piston if it is subjected to
a pressure of 3000 Pa and has surface area of 2.5 m2?.
Option A.
7500 N.
Option B.
3000 N.
Option C.
1200 N.
Correct
Answer is. 7500 N.
Explanation.
Force = pressure * area = 3000 * 2.5 = 7.5 N.
Question
Number. 40. A force of 10 million Newton’s is expressed numerically
as.
Option A.
10 MN.
Option B.
10 MN.
Option C.
1 MN.
Correct
Answer is. 10 MN.
Explanation.
million Newtons = 10 MN (MegaNewtons).
Question
Number. 41. A millilitre is equal to.
Option A.
one million litres.
Option B.
one millionth of a litre.
Option C.
one thousandth of a litre.
Correct
Answer is. one thousandth of a litre.
Explanation.
A millilitre = 1/1000 litre.
Question
Number. 42. If a square has an area of 9m2,
one side is.
Option A.
3 m.
Option
B. 3 m2.
Option C.
3 sq. m.
Correct
Answer is. 3 m.
Explanation.
3 m * 3m = 9 m2.
Question
Number. 43. A vector quantity is a quantity which.
Option A.
possesses sense, magnitude and direction.
Option B.
possesses direction only.
Option C.
possesses sense only.
Correct
Answer is. possesses sense, magnitude and direction.
Explanation.
A vector quantity has magnitude AND direction. (sense and direction
are the same thing).
Question
Number. 44. One atmosphere is equal to.
Option
A. 1.22 kg/m2.
Option
B. 14.7 lbf/in2.
Option C.
28.9 inches of Hg.
Correct
Answer is. 14.7 lbf/in2.
Explanation.
atmosphere = 14.7 pounds-force (lbf) per square inch.
Question
Number. 45. Strain is calculated by.
Option A.
Original Length * Extension.
Option B.
Extension ÷ Original Length.
Option C.
Original Length ÷ Extension.
Correct
Answer is. Extension ÷ Original Length.
Explanation.
Strain = change in length divided by original length.
Question
Number. 46. When a twisting force is applied to a bolt, what stress
is exerted on to the head?.
Option A.
Shear.
Option B.
Compressive.
Option C.
Torsion.
Correct
Answer is. Torsion.
Explanation.
A twisting force applied to a bolt produces 'torsion stress' (which
technically is a form of shear).
Question
Number. 47. When you overstress a steel bar, what is the point called
where it does not return to its original form?.
Option A.
Plastic limit.
Option B.
Elasticity limit.
Option C.
Deformation limit.
Correct
Answer is. Elasticity limit.
Explanation.
The point at which the stressed bar does not return to its original
form is called the 'elastic limit'.
Question
Number. 48. The formula for calculating shear is.
Option A.
force ÷ cross-sectional area.
Option B.
force * area.
Option C.
force ÷ area parallel to the force.
Correct
Answer is. force ÷ area parallel to the force.
Explanation.
Formula for shear (stress) is Shear stress = force/area parallel to
force.
Question
Number. 49. A force 10 N is placed 2 Meters from a pivot point, what
is the moment?.
Option A.
20 Nm.
Option B.
20 Nm.
Option C.
80 Nm.
Correct
Answer is. 20 Nm.
Explanation.
N at 2 m distance produces 10 * 2 = 20 Nm.
Question
Number. 50. If a tensile load is placed on a bar, it will.
Option A.
bend.
Option B.
crush.
Option C.
stretch.
Correct
Answer is. stretch.
Explanation.
tensile load placed on a bar will stretch it.
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