1) Principle plane is a plane on which the shear stress is_______
a) Zero
b) Minimum
c) Maximum
d) None of above
Ans: a
b) Minimum
c) Maximum
d) None of above
Ans: a
2) A thin spherical shell of diameter (d) and thickness (t) is subjected to an internal pressure ( p). The stress in the shell material is
a) pd/t
b)pd/2t
c) pd/4t
d) pd/8t
Ans: c
a) pd/t
b)pd/2t
c) pd/4t
d) pd/8t
Ans: c
3) Compression members always tend to buckle in the direction of the _________
a) axis of load
b) perpendicular to the axis of load
c) minimum cross section
d) least radius of gyration
Ans: d
4) A screw is said to be over hauling screw, if its efficiency is ________
a) less than 50%
b) more than 50%
c) equal to 50%
d) none of these
Ans: b
5) In a flange coupling, the flanges are coupled together by means of _______
a) bolts and nuts
b) studs
c) headless taper bolts
d) none of these
Ans: a
6) Slenderness ratio is the ratio of __________
a) maximum size of column to minimum size of column
b) width of column to depth of column
c) effective length of column to least radius of gyration of the column
d) effective length of column to width of column
Ans: c
b) width of column to depth of column
c) effective length of column to least radius of gyration of the column
d) effective length of column to width of column
Ans: c
7) A column is known as a long column if the slenderness ratio is _________
a) 40
b) 50
c) 70
d) 100
Ans: d
8) When screw threads are to be used in a situation where power is being transmitted in one direction only, then the screw threads suitable for this will be __________
a) square threads
b) acme threads
c) knuckle threads
d) buttress threads
Ans: d
9) The value of stress concentration factor depends upon ________
a) material of the part
b) geometry of the part
c) material and geometry of the part
d) none of these
Ans: c
10) Which of the following material has the maximum ductility?
a) Mild steel
b) Copper
c) Zinc
d) Aluminium
Ans: a
11) According to Guest's theory, the failure occurs at a point in a member when the maximum
shear stress in a bi-axial stress system reaches the shear stress at elastic limit in simple tension
test.
a) True
b) False
Ans: a
12) Which of the following statement is correct for gears?
a) The addendum is less than dedendum
b) The pitch circle diameter is equal to the product of module and number of teeth
c) The pitch circle is always greater than the base circle
d) all of the above
Ans: d
13) Stress concentration is caused due to ________
a) variations in load acting on a member
b) variations in properties of materials in a member
c) abrupt change of cross-section
d) all of these
Ans: c
14) The resistance to fatigue of a material is measured by ______
a) elastic limit
b) Young's modulus
c) ultimate tensile strength
d) endurance limit
Ans: d
15) The load cup of a screw jack is made separate from the head of the spindle to ______
a) enhance the load carrying capacity of the jack
b) reduce the effort needed for lifting the working load
c) prevent the rotation of load being lifted
d) reduce the value of frictional torque
Ans: c
16) The rolling contact bearings are known as _________
a) thick lubricated bearings
b) plastic bearings
c) thin lubricated bearings
d) antifriction bearings
Ans: d
17) The backlash for spur gears depends upon ______
a) module
b) pitch line velocity
c) tooth profile
d) both (a) and (b)
Ans: d
18) The taper on cotter varies from ______
a) 1 in l5 to 1 in 10
b) 1 in 24 to 1 in 20
c) 1 in 32 to 1 in 24
d) 1 in 48 to 1 in 24
Ans: d
19) The rolling contact bearings as compared to sliding contact bearings have _________
a) small overall dimensions
b) accuracy of shaft alignment
c) low starting and low running friction except at very high speeds
d) all of the above
Ans: d
20) The maximum normal stress theory is used for ______
a) brittle materials
b) ductile materials
c) plastic materials
d) non-ferrous materials
Ans: a
21) When two non-intersecting and non-coplaner shafts are connected by gears, the arrangement
is known as ________
a) spur gearing
b) helical gearing
c) bevel gearing
d) spiral gearing
Ans:d
22) When a nut is tightened by placing a washer below it, the bolt will be subjected to ________
a) tensile stress
b) compressive stress
c) shear stress
d) none of these
Ans: a
23) The difference between the tooth space and the tooth thickness as measured on the pitch
circle, is called _______
a) working depth
b) clearance
c) face width
d) backlash
Ans: d
24) The endurance limit for a mirror polished material will be __________ as compared to
unpolished material.
a) Same
b) Less
c) More
d) None of above
Ans: c
25) Which of the following statement is correct ?
a) The toughness of a material increases when it is heated.
b) The shear stress in a beam varies from zero at the neutral surface and maximum at the outer
fibres.
c) The stress concentration in static loading is more serious in brittle materials and less serious in
ductile materials.
d) The stress concentration in static loading is more serious in ductile materials and less serious
in brittle materials.
Ans: c
26) Which of the following is an antifriction bearing?
a) journal bearing
b) pedestal bearing
c) collar bearing
d) needle bearing
Ans: d
27) In designing a sleeve coupling, length of the sleeve is taken as (where d = Diameter of the
shaft)
a) d + 17 mm
b) 2 d + 13 mm
c) 2 d + 20 mm
d) 3.5 d
Ans: d
28) The modulus of elasticity for mild steel is approximately equal to _____
a) 80 kN/mm2
b) 100 kN/mm2
c) 110 kN/mm2
d) 210 kN/mm2
Ans: d
29) The cross-section of the arm of a bell crank lever is __________
a) rectangular
b) elliptical
c) I-section
d) any one of these
Ans: d
30) When spring index increases, the value of Wahl's stress factor _____
a) increases linearly
b) decreases linearly
c) remains same
d) increases exponentially
Ans: d
31) A shaft is subjected to a maximum bending stress of 80 N/mm2
and maximum shearing stress
equal to 30 N/mm2
at a particular section. If the yield point in tension of the material is 280
N/mm2
and the maximum shear stress theory of failure is used, then the factor of safety obtained
will be ______
a) 2.5
b) 2.8
c) 3.0
d) 3.5
Ans: b
32) The longitudinal stress is __________ of the circumferential stress.
a) one-half
b) two-third
c) three-fourth
d) double
Ans: a
33) A screw will be self locking, if ________
a) friction angle is less than helix angle
b) friction angle is more than helix angle
c) friction angle is equal to helix angle
d) efficiency of screw is 100%
Ans: b
34) The maximum shear stress theory is used for _________
a) brittle materials
b) ductile materials
c) plastic materials
d) non-ferrous materials
Ans: b
35) Which of the following statement is correct ?
a) A parallel sunk key is a taperless key
b) A parallel sunk key may be rectangular or square in cross-section
c) A flat saddle key is a taper key which fits in a key way of the hub and is flat on the shaft
d) all of the above
Ans: d
36) A bolt of uniform strength can be developed by ______
a) keeping the core diameter of threads equal to the diameter of unthreaded portion of the bolt
b) keeping the core diameter smaller than the diameter of the unthreaded portion
c) keeping the nominal diameter of threads equal to the diameter of unthreaded portion of the
bolt
d) none of the above
Ans: a
37) A localised compressive stress at the area of contact between two members which have
relative motion between them is known as ___
a) tensile stress
b) bending stress
c) bearing stress
d) crushing stress
Ans: c
38) A taper key which fits half in the key way of the hub and half in the key way of shaft, is
known as
a) sunk key
b) flat saddle key
c) hollow saddle key
d) tangent key
Ans: a
39) A machine part subjected to __________ is called a strut.
a) an axial tensile force
b) an axial compressive force
c) a tangential force
d) any one of these
Ans: b
40) The yield point in static loading is __________ as compared to fatigue loading.
a) higher
b) lower
c) same
d) Can’t able to tell
Ans: a
41) Two closely coiled helical springs with stiffnesses K1 and K2 respectively are connected in
series. The stiffness of an equivalent spring is given by _________
a) (K1 K2) / (K1+K2)
b)(K1 – K2) / (K1 + K2)
c) (K1 + K2) / K1 K2
d) (K1 – K2) / K1 K2
Ans: a
42) A wood-ruff key is _______
a) a tapered key with head at one end
b) fitted in pairs at right angles
c) capable of tilting in a recess milled out in the shaft
d) all of the above
Ans: c
43) Which of the following spring is used in mechanical wrist watch? ______
a) Helical compression spring
b) Spiral spring
c) Torsion spring
d) Bellevile spring
Ans: c
44) The ratio of the ultimate stress to the design stress is known as ________
a) elastic limit
b) strain
c) factor of safety
d) bulk modulus
Ans:c
45) The transverse fillet welded joints are designed for _______
a) tensile strength
b) compressive strength
c) bending strength
d) shear strength
46) When a beam of rectangular cross-section of width b and depth d, is subjected to a shear
force F, the maximum shear stress induced will be ______
a) F/ (bh)
b) 3F/ (2 bh)
c) 2F / (bh)
d) 4F / (bh)
Ans: b
47) Which one of the following loading is considered for the design of axles?
a) Bending moment only
b) Twisting moment only
c) Combined bending moment and twisting moments
d) Combined action of bending moment, twisting moment and axial thrust
Ans: a
48) In levers, leverage is the ratio of ________
a) load lifted to the effort applied
b) mechanical advantage to the velocity ratio
c) load arm to the effort arm
d) effort arm to the load arm
Ans: d
49) A shaft is subjected to fluctuating loads for which the normal torque (T) and bending
moment (M) are 1000 N-m and 500 N-m respectively. If the combined shock and fatigue factor
for bending is 1.5 and combined shock and fatigue factor for torsion is 2, then the equivalent
twisting moment for the shaft is _____
a) 2000 N-m
b) 2050 N-m
c) 2100 N-m
d) 2136 N-m
Ans: d
50) A hollow saddle key is _________
a) a taper key which fits half in the key way of hub and half in the key way of shaft
b) a taper key which fits in a key way of the hub and is flat on the shaft
c) a taper key which fits in a key way of the hub and the bottom of the key is shaped to fit the
curved surface of the shaft
d) provided in pairs at right angles and each key is to withstand torsion in one direction only
Ans: c
51) Which of the following welded joint is designed for shear strength ?
a) Transverse fillet welded jointZ
b) Parallel fillet welded joint
c) Butt welded joint
d) all of these
Ans: b
52) The endurance or fatigue limit is defined as the maximum value of the stress which a
polished standard specimen can withstand without failure, for infinite number of cycles, when
subjected to __
a) static load
b) dynamic load
c) static as well as dynamic load
d) completely reversed load
Ans: d
53) Failure of a material is called fatigue when it fails _______
a) at the elastic limit
b) below the elastic limit
c) at the yield point
d) below the yield point
Ans:d
54) According to Rankine's theory, the failure occurs at a point in a member
a) when the maximum shear stress in a bi-axial stress system reaches the shear stress at elastic
limit in a simple tension test
b) when the maximum principal stress in a bi-axial stress system reaches the elastic limit of the
material in a simple tension test
c) when the strain energy per unit volume in a bi-axial stress system reaches the strain energy at
the elastic limit per unit volume as determined from a simple tension test
d) when the maximum principal strain in a bi-axial stress system reaches the strain at the elastic
limit as determined from a simple tension test
Ans: b
55) The dedendum is the radial distance from the _____
a) pitch circle to the top of a tooth
b) pitch circle to the bottom of a tooth
c) top of a tooth to the bottom of a tooth
d) addendum circle to the clearance circle
Ans:b
56) A shaft coupling should _____
a) be easy to connect or disconnect
b) transmit full power of the shaft
c) hold the shafts in perfect alignment
d) all of these
Ans: d
57) The usual proportion for the width of key is (where d = Diameter of shaft or diameter of hole
in the hub)
a) d/8
b) d/6
c) d/4
d) d/2
Ans:c
58) n a transverse fillet welded joint, the size of weld is __________ the throat of weld.
a) 0.5 times
b) equal to
c) √2 times
d) double
Ans: c
59) The included angle for the British standard whitworth thread is _____
a) 29°
b) 47.5°
c) 55°
d) 60°
Ans: c
60) Two shafts will have equal strength, if ________
a) diameter of both the shafts is same
b) angle of twist of both the shafts is same
c) material of both the shafts is same
d) twisting moment of both the shafts is same
Ans: d
61) Which of the following coupling is used to connect two shafts which have both lateral and
angular misalignment?
a) Bushed pin type coupling
b) Universal coupling
c) Oldham coupling
d) all of these
Ans: d
62) A screw is said to be over hauling screw, if the _________
a) friction angle is less than helix angle
b) friction angle is more than helix angle
c) friction angle is equal to helix angle
d) efficiency of screw is 100%
Ans: a
63) Shaft coupling is used in machinery to _______
a) introduce mechanical flexibility
b) introduce protection against over loads
c) reduce the transmission of shock loads
d) all of these
Ans: d
64) An open coiled helical compression spring 'A' of mean diameter 50 mm is subjected to an
axial load W. Another spring 'B' of mean diameter 25 mm is similar to spring 'A' in all respects.
The deflection of spring 'B' will be __________ as compared to spring 'A'.
a) one-eighth
b) one-fourth
c) one-half
d) double
Ans: a
65) Which of the following statement is wrong ?
a) The solid length of a spring is the product of total number of coils and the diameter of the wire
b) The spring index is the ratio of mean diameter of the coil to the diameter of the wire
c) The spring stiffness is the load required per unit deflection of the spring
d) The pitch of the coil is the axial distance between adjacent coils in the compressed state
Ans: d
66) Deep groove ball bearings are used for _________
a) heavy thrust load only
b) small angular displacement of shafts
c) radial load at high speed
d) combined thrust and radial loads at high speed
Ans: d
67) When a load W is applied suddenly on a bar of cross-sectional area A, the stress induced in
the bar will be ______
a) W / A
b) W / 2A
c) 2W / A
d) 3W / A
Ans: c
68) In a butt welded joint, the size of weld is __________ the throat of weld.
a) 0.5 times
b) equal to
c) √2 times
d) double
Ans: b
69) Which of the following key is preferred for the condition when a large amount of impact
type torque is to be transmitted in both direction of rotation?
a) Woodruff key
b) Feather key
c) Gib-head key
d) Tangent key
Ans: d
70) Factor of safety for fatigue loading is the ratio of ______
a) elastic limit to the working stress
b) elastic limit to the yield point
c) endurance limit to the working stress
d) Young's modulus to the ultimate tensile strength
Ans: c
71) In a flange coupling, the bolts are subjected to _______
a) tensile stress
b) compressive stress
c) shear stress
d) none of these
Ans: c
72) A key made from a cylindrical disc having segmental cross-section, is known as ________
a) feather key
b) gib-head key
c) wood ruff key
d) flat saddle key
Ans: c
73) Which of the following screw thread is adopted for power transmission in either direction?
a) Acme threads
b) Square threads
c) Buttress threads
d) Multiple threads
Ans: b
74) In the assembly of pulley, key and shaft _______
a) pulley is made the weakest
b) key is made the weakest
c) key is made the stongest
d) all the three are designed for equal strength
Ans: b
75) The fatigue stress concentration factor is defined as _________
a) the ratio of endurance limit with stress concentration to the endurance limit without stress
concentration
b) the ratio of endurance limit without stress concentration to the endurance limit with stress
concentration
c) the product of the endurance limits with and without stress concentration
d) all of the above
Ans: b
76) In a turnbuckle, if one of the rods has left hand threads, then the other rod will have
_________
a) right hand threads
b) left hand threads
c) multiple threads
d) pointed threads
Ans: a
77) A cotter joint is used to transmit ________
a) axial tensile load only
b) axial compressive load only
c) combined axial and twisting loads
d) axial tensile or compressive loads
Ans: d
78) The taper on a rectangular sunk key is ________
a) 1 in 16
b) 1 in 32
c) 1 in 48
d) 1 in 100
Ans: d
79) Which of the following statement is correct regarding power screws?
a) The efficiency of a self locking screw can not be more than 50%
b) The efficiency of Acme (trapezoidal) thread is less than that of a square thread
c) If the friction angle is less than the helix angle of the screw, then the efficiency will be more
than 50%
d) (A) and (B) Only
Ans: d
80) A flange coupling is used to connect two shafts ________
a) which are perfectly aligned
b) which are not in exact alignment
c) have lateral misalignment
d) whose axes intersect at a small angle
Ans: a
81) When an open coiled helical compression spring is subjected to an axial compressive load,
the stress induced in the wire is ________
a) tensile stress
b) compressive stress
c) shear stress
d) bending stress
Ans: c
82) The ratio of circumferential stress to longitudinal stress in a thin cylinder subjected to an
internal pressure is _______
a) 1/2
b) 1
c) 2
d) 4
Ans: c
83) When the material of key and shaft is same, and the width of key is one-fourth of the
diameter of shaft (d), then length of key will be ______
a) 0.8 d
b) 1.2 d
c) 1.57 d
d) 1.8 d
Ans: c
84) Which of the following statement is wrong ?
a) A key is used as a temporary fastening
b) A key is subjected to tensile stresses
c) A key is always inserted parallel to the axis of the shaft
d) A key prevents relative motion between the shaft and boss of the pulley
Ans: b
85) A screw is said to be a self locking screw, if its efficiency is _______
a) less than 50 %
b) more than 50%
c) equal to 50%
d) none of these
Ans: a
86) The ratio of pitch circle diameter in millimetres to the number of teeth, is called ______
a) circular pitch
b) diametral pitch
c) module
d) none of these
Ans: c
87) In designing a flange coupling, the pitch circle diameter of bolts is taken as (where d =
Diameter of the shaft)
a) 2 d
b) 3 d
c) 4 d
d) 5 d
Ans: b
88) The acme threads are usually found on ________
a) spindles of bench vices
b) railway carriage couplings
c) feed mechanism of machine tools
d) screw cutting lathes
Ans: d
89) The efficiency of a square threaded screw is maximum if the helix angle is equal to (where φ
= Angle of friction)
a) 90° - φ
b) 45° - φ
c) 45° - φ/2
d) 45° + φ/2
Ans: c
90) Which of the following property is essential for spring materials?
a) Stiffness
b) Ductility
c) Resilience
d) Plasticity
Ans: c
b) Ductility
c) Resilience
d) Plasticity
Ans: c
91) In static loading, stress concentration is more serious in _________
a) brittle materials
b) ductile materials
c) brittle as well as ductile materials
d) elastic materials
Ans: a
92) A column of length l is fixed at both ends. The equivalent length of the column is
a) l / 2
b) l / √2
c) l
d) 2 l
Ans: a
93) The stiffness of a closely coiled helical spring subjected to an axial load W is equal to
(where G = Modulus of rigidity, and n = Number of active coils)
a) G d⁴/(8 D³ n)
b) G d³/(8 D³ n)
c) G d⁴/(4 D³ n)
d) G d⁴/(8 D² n)
Ans: a
94) The diameter of knuckle pin in a knuckle joint is usually taken as (where d = Diameter of the
rod)
a) 0.5 d
b) 0.8 d
c) d
d) 1.2 d
Ans: c
rod)
a) 0.5 d
b) 0.8 d
c) d
d) 1.2 d
Ans: c
95) The design of shafts made of brittle materials is based on _______
a) Guest's theory
b) Rankine's theory
c) St Venant's theory
d) VonMises theory
Ans: b
97) The notch sensitivity q is expressed in terms of fatigue stress concentration factor Kf and
theoretical stress concentration factor Kt, as
a) (Kf + 1) / (Kt + 1)
b) (Kf - 1) / (Kt - 1)
c) (Kt + 1) / (Kf + 1)
d) (Kt + 1) / (Kf + 1)
theoretical stress concentration factor Kt, as
a) (Kf + 1) / (Kt + 1)
b) (Kf - 1) / (Kt - 1)
c) (Kt + 1) / (Kf + 1)
d) (Kt + 1) / (Kf + 1)
Ans: B
98) ______ is the diameter of an imaginary cylinder
on a cylindrical screw thread it is also known as
effective diameter .
a) Base circle
b) pitch circle
c) Over all
d) none of the above
Ans: b
99) The distance through which a screw advances
axially in one rotation of the nut is called as
a) Lead of the screw
b) pitch of the screw
c) pitch point
d) pitch line
Ans: a
100) Initial stresses in the screws are
a)Tensile stress
b)Torsional shear stress
c) Shear stress
d) All of above
Ans: d