← MES Jr. Grade
Past Questions
Rivets are generally specified by
A)
thickness of plates to be riveted
B)
length of rivet
C)
diameter of head
D)
nominal diameter
Rivets are generally specified by their nominal diameter (and sometimes length as well, depending on the context). In standard engineering practice, the primary size designation of a rivet is its nominal diameter, so option d is correct. The diameter of the head is not used for specification because head dimensions vary with rivet type and standard. The length of the rivet is not the general specification term; it is selected based on plate thickness and required shop allowance. Thickness of plates to be riveted is a design input, not the rivet specification itself.
If a shaft is rotating N revolutions per minute with an applied torque T kg-m, the horse power being transmitted by the shaft is,
A)
2pNT/550
B)
2pNT/750
C)
2pNT/4500
D)
2pNT/5500
For torque T in kg-m and speed N rpm, horsepower is 2πNT/4500, giving option C.
The shock absorbing capacity of a bolt can be increased by
A)
making shank diameter equal to core diameter thread
B)
tightening it properly
C)
grinding the shank
D)
using washer
The shock-absorbing capacity of a bolt increases when the shank is made more flexible, so it can elongate slightly and absorb impact energy. Grinding the shank reduces its diameter and therefore increases its elasticity and ability to absorb shock loads.
Why others are incorrect:
- (b) Tightening it properly mainly ensures clamping force; it does not increase shock absorption capacity.
- (d) Using a washer helps distribute load and protect the surface, but it does not significantly improve shock absorption.
- (a) Making shank diameter equal to core diameter of thread is not the usual method for increasing shock absorption; the shank should be more flexible than the threaded portion, not simply equal to the thread core diameter.
The property of a material by which it can be drawn to a smaller section, due to tension, is called
A)
plasticity
B)
ductility
C)
elasticity
D)
malleability
Ductility is the property of a material that allows it to be drawn out into a smaller cross-section under tensile stress, such as being drawn into wire. Hence, option b is correct. Plasticity is the ability to undergo permanent deformation without rupture, malleability is the ability to be hammered or rolled into thin sheets, and elasticity is the ability to regain original shape after removal of load; therefore, these are not the correct terms here.
In a solid arch, shear force acts
A)
Vertically upwards
B)
Along the axis of the arch
C)
Perpendicular to the axis of the arch
D)
tangentially to the arch
Option C: Perpendicular to the axis of the arch. This matches the standard definition or established fact for the concept asked.
Dynamic friction as compared to static friction is
A)
same
B)
more
C)
less
D)
may be less or more depending on nature of surfaces and velocity
Option C: less. This matches the standard definition or established fact for the concept asked.
For maximum torque condition, the crank angle is,
A)
0° from top dead centre for petrol and diesel engines
B)
33° before top dead centre for petrol engine and 1° after top dead centre position for diesel engine
C)
25° to 35° for petrol engine and 30° to 40° for diesel from top dead centre
D)
90° from top dead centre for petrol and diesel engines
Maximum torque in I.C. engines occurs when the pressure rise and crank effort are most effective after ignition/injection, which is typically a few degrees after top dead centre (TDC) for both petrol and diesel engines. In practice, the crank angle for maximum torque is about 25° to 35° from TDC for petrol engines and about 30° to 40° from TDC for diesel engines, so option (c) is correct.
Why the others are wrong:
- (a) 0° from TDC is not the maximum torque position; at TDC the crank has no effective leverage.
- (b) The stated angles are not the standard maximum-torque crank angles; petrol engines do not reach maximum torque at 33° before TDC, and diesel engines do not do so at 1° after TDC.
- (d) 90° from TDC is the position of maximum mechanical advantage of the crank, but not the actual maximum torque condition in engines because cylinder pressure is not maximum there.
In the lever of third order, load W, effort P and fulcrum F are oriented as follows
A)
W between P and F
B)
F between W and P
C)
P between W and F
D)
none of these
In a third-order lever, the effort lies between the fulcrum and the load. Therefore the arrangement is F — P — W (or W — P — F), which matches option (c): P between W and F. Option (a) is incorrect because if W is between P and F, the load is in the middle, which is not a third-order lever. Option (b) describes a first-order lever, where the fulcrum is between load and effort. Option (d) is incorrect because option (c) is the correct arrangement.
A beam is said to be of uniform strength, if
A)
Bending moment is same throughout the beam
B)
Deflection is same throughout the beam
C)
Bending stress is same throughout the beam
D)
shear stress is same throughout the beam
A beam has uniform strength when its bending stress is maintained at the same allowable value throughout.
The deflection of a cantilever beam under load W is 8. If its width is halved, then the deflection under load W will be
A)
28
B)
48
C)
58
D)
68
For a cantilever beam, deflection under a given load is inversely proportional to the second moment of area (I). For a rectangular section, I = bd^3/12 when bending is about the axis parallel to width b, so deflection is inversely proportional to b. If the width is halved, I becomes half, so deflection doubles. Hence the new deflection = 2 × 8 = 16, which corresponds to option d (68 as written in the options, intended to mean 16). The other options are incorrect because they do not reflect the inverse proportionality between deflection and width for a rectangular beam section.
A trolley wire weighs 1.2 kg per meter length. The ends of the wire are attached to two poles 20 meters apart. If the horizontal tension is 1500 kg, find the dip in the middle of the span
A)
2.5 cm
B)
3.0 cm
C)
4.0 cm
D)
5.0 cm
For a lightly sagging wire, the dip at midspan is given by the parabolic approximation:
h = (w L^2) / (8 T)
where w = weight per meter = 1.2 kg/m, L = span = 20 m, and T = horizontal tension = 1500 kg.
So,
h = (1.2 × 20^2) / (8 × 1500)
= (1.2 × 400) / 12000
= 480 / 12000
= 0.04 m
= 4.0 cm
Hence the correct option is c.
Why the others are incorrect:
- a (2.5 cm): too small; would correspond to a much larger tension or smaller weight/span.
- b (3.0 cm): close but not equal to the computed value.
- d (5.0 cm): too large; would require less tension or more weight/span.
Note: The computed dip is 4.0 cm, so the correct option is c.
Forces are called concurrent when their lines of action meet in
A)
one point
B)
two point
C)
plane
D)
perpendicular plain
Option A: one point. This matches the standard definition or established fact for the concept asked.
The ratio of endurance limit in shear to the endurance limit in flexure is
A)
0.33
B)
0.5
C)
0.55
D)
0.44
For ductile materials, the endurance limit in shear is commonly taken as about 0.5 times the endurance limit in flexure (bending). This comes from the usual fatigue strength relation between shear and normal stress amplitudes. Hence, the correct ratio is 0.5.
Why the others are incorrect:
- 0.33: too low; this is not the standard shear-to-flexure endurance limit ratio.
- 0.44: close to some static shear-to-tension approximations, but not the accepted fatigue ratio here.
- 0.55: slightly higher than the standard value; not the usual design/exam answer.
Therefore, the correct option is b.
Residual stress in materials
A)
is independent of external load
B)
is always harmful
C)
is always beneficial
D)
acts when external load is applied
Residual stress is the stress that remains locked inside a material even after the external load or cause has been removed. Therefore, it exists independently of the external load, which makes option (a) correct. Option (d) is incorrect because residual stress is not caused by the current applied load; it remains when the load is removed. Option (c) is incorrect because residual stress can be either beneficial or harmful depending on its nature and distribution. Option (b) is incorrect because residual stress is not always harmful; for example, compressive residual stresses can improve fatigue life.
Effect of force on a body depends upon
A)
magnitude
B)
direction
C)
line of action
D)
all of these
The effect of a force on a body depends on its magnitude, direction, and line of action. Magnitude determines how strong the force is, direction determines the sense in which it acts, and the line of action determines the turning effect or tendency to rotate. Therefore, all three factors together decide the effect of the force, so option d is correct. Options a, b, and c are incorrect individually because each mentions only one factor, whereas the effect of a force cannot be fully described by any single one of them alone.
If two moving elements have surface contact in motion, such pair is known as
A)
sliding pair
B)
rolling pair
C)
higher pair
The correct answer is **higher pair**. In kinematics, a **higher pair** is a pair of elements having **surface or point contact** while in relative motion. Since the question states that two moving elements have **surface contact in motion**, it matches the definition of a higher pair.
Why the others are incorrect:
- **Sliding pair**: has **surface contact**, but the motion is **pure sliding** between the surfaces; the standard classification here is based on the type of relative motion, not just surface contact.
- **Rolling pair**: has **rolling contact** between the elements, not general surface contact in motion.
Therefore, the correct option is **c**.
Push rod is designed on the basis of,
A)
tensile strength
B)
compressive strength
C)
bending strength
D)
buckling strength
A push rod in a mechanism is subjected mainly to axial compressive load, so it is designed on the basis of buckling strength rather than simple material strength. Since it is a slender member, failure is more likely by lateral buckling under compression than by crushing. Hence option (d) buckling strength is correct. Tensile strength is incorrect because the push rod does not primarily carry tension. Compressive strength is not the governing criterion for a slender rod because buckling occurs before the material reaches crushing stress. Bending strength is also incorrect because bending is not the primary mode of loading for a push rod.
The tensile force required to cause an elongation 0.045 mm in a steel rod of 1000 mm length and 12 mm diameter, is (where E= 2×106 kg/cm2)
A)
166 kg
B)
102 kg
C)
204 kg
D)
74 kg
Use the axial deformation relation: \(\delta = \frac{PL}{AE}\), so \(P = \frac{\delta AE}{L}\).
Given:
- \(\delta = 0.045\,\text{mm} = 0.0045\,\text{cm}\)
- \(L = 1000\,\text{mm} = 100\,\text{cm}\)
- \(d = 12\,\text{mm} = 1.2\,\text{cm}\)
- \(A = \frac{\pi d^2}{4} = \frac{\pi(1.2)^2}{4} \approx 1.131\,\text{cm}^2\)
- \(E = 2\times 10^6\,\text{kg/cm}^2\)
Now,
\[
P = \frac{0.0045 \times 1.131 \times 2\times 10^6}{100}
\approx 102\,\text{kg}
\]
So the correct option is **b) 102 kg**.
Why the others are incorrect:
- **a) 166 kg**: too high; would correspond to a larger elongation or smaller length.
- **c) 204 kg**: about double the correct value, likely from a calculation error in area or unit conversion.
- **d) 74 kg**: too low; would result from underestimating the area or modulus.
Hence, the required tensile force is **102 kg**.
If a circular beam of diameter d experiences a longitudinal strain P/E and a lateral strain 2P/mE, the volumetric strain is
A)
(P/E)+ (2P/mE)
B)
(P/E)- (2P/mE)
C)
(P/E)+ (mE/2P)
D)
(P/E)- (mE/2P)
For a beam under axial loading, volumetric strain is the sum of the normal strains in three mutually perpendicular directions:
Volumetric strain = longitudinal strain + lateral strain + lateral strain.
Here, longitudinal strain = P/E. The given lateral strain is 2P/mE, and since lateral strain under tension is opposite in sign to longitudinal strain, it is taken as negative. Thus,
Volumetric strain = (P/E) - 2(P/mE).
Among the options, this corresponds to option b.
Why others are wrong:
- a: adds the lateral strain instead of subtracting it, which ignores the opposite sign of lateral contraction.
- c and d: contain mE/2P, which is the reciprocal form and not a strain expression, so they are dimensionally incorrect.
The number of links in pantograph mechanism is equal to
A)
2
B)
3
C)
4
D)
5
A pantograph mechanism is a four-bar linkage arrangement used for copying or scaling motion, so it has 4 links. Therefore, option (c) is correct. Option (a) = 2 is too few for a mechanism, option (b) = 3 corresponds to a simple three-link mechanism, and option (d) = 5 is more than the standard pantograph linkage.
If a rigid body is in equilibrium under the action of three forces, then
A)
these forces are equal
B)
these forces are not equal
C)
the lines of action of these forces are parallel
D)
none of these
For a rigid body to be in equilibrium under three forces, the forces must satisfy both force and moment equilibrium. In general, three forces in equilibrium must be either concurrent or all parallel, and their vector sum must be zero. However, the statement given in the options is incomplete: the forces need not be equal, and their lines of action need not always be parallel. Therefore, none of the listed statements is universally true.
Why the other options are incorrect:
- a) "these forces are equal" — Not necessarily. Three forces can be in equilibrium with different magnitudes, provided they balance vectorially.
- b) "these forces are not equal" — Also not necessarily true, because they may be equal in special cases (e.g., three equal forces at 120° to each other).
- c) "the lines of action of these forces are parallel" — This is only one possible case, not a general requirement. Three forces in equilibrium may be concurrent instead.
Hence, the correct answer is d) none of these.
The spring index for valve spring is usually
A)
6
B)
8
C)
10
D)
12
The spring index is the ratio of mean coil diameter to wire diameter (C = D/d). For valve springs, a moderate spring index is usually preferred to balance manufacturability, stress concentration, and fatigue life. The commonly used value is about 8, so option (b) is correct. Option (a) 6 is too low and makes the spring too tight with higher stress concentration; options (c) 10 and (d) 12 are higher than usual and can make the spring more flexible but less compact and may increase buckling/space issues in valve applications.
Coaxing is the procedure of increasing
A)
metal strength by cycling
B)
fatigue limit by overstressing the metal by successively increasing loadings
C)
metal resistance to corrosion by coating
D)
metal hardness by surface treatment
Coaxing is the process of increasing the fatigue limit of a metal by subjecting it to repeated loading with successively increasing stress levels, so the material becomes less sensitive to fatigue failure. Hence option (b) is correct.
Option (a) is incorrect because cycling alone refers to repeated loading, but coaxing specifically means increasing the fatigue limit by progressively higher loads. Option (c) is incorrect because coating improves corrosion resistance, not coaxing. Option (d) is incorrect because surface treatment may increase hardness, but that is unrelated to coaxing.
Pick up the incorrect statement from the following:
A)
The C.G. of a circle is at its center
B)
The C.G. of a triangle is at the intersection of its medians
C)
The C.G. of a rectangle is at the intersection of its diagonals
D)
The C.G. of a semicircle is at a distance of r/2 from the center
Option (d) is incorrect. The centroid (C.G.) of a semicircular area lies on its axis of symmetry at a distance of 4r/(3\pi) from the center, not r/2. The value r/2 is wrong.
The other statements are correct: (a) the centroid of a circle (uniform lamina) is at its center; (b) the centroid of a triangle is at the intersection of its medians; and (c) the centroid of a rectangle is at the intersection of its diagonals.
Which of the following is a vector quantity
A)
energy
B)
mass
C)
momentum
D)
speed
Momentum is a vector quantity because it has both magnitude and direction, and its direction is the same as the velocity of the body. Energy, mass, and speed are scalar quantities: they have magnitude only and no direction.