190+ Design of Machine Elements Solved MCQs

1.

Stressed parts are always kept in tension.

A. true
B. false
Answer» A. true
Explanation: cast iron has more compressive strength.
2.

Which process allows controlling grain structure of the product?

A. casting
B. forging
C. none of the mentioned
D. die casting
Answer» B. forging
Explanation: in casting metal is in fluid state and hence impossible to control the grain structure.
3.

Cast surfaces have good finishing.

A. true
B. false
Answer» B. false
Explanation: cavity is surrounded by sand and hence not good finish is obtained.
4.

In forging, metal is in which of the following stage?

A. elastic
B. plastic
C. can be in any stage
D. rigid
Answer» B. plastic
Explanation: forging is the working of metal in plastic range.
5.

Among casting, forging and forging which has the slowest rate of production?

A. casting
B. forging
C. machining
D. all have equal rate of production
Answer» C. machining
Explanation: machining each part is very time consuming.
6.

In manual assembly, cost of screw is higher than the cost of driving a screw.

A. true
B. false
Answer» B. false
Explanation: generally manufacturing screw is cheaper than driving it.
7.

Maximum carbon content in welding is usually limited to

A. 0.22%
B. 0.8%
C. 1.5%
D. 2%
Answer» A. 0.22%
Explanation: with increase of carbon, welding becomes difficult as weld becomes susceptible to cracks.
8.

Why tolerances are given to the parts?

A. because it’s impossible to make perfect settings
B. to reduce weight of the component
C. to reduce cost of the assembly
D. to reduce amount of material used
Answer» A. because it’s impossible to make perfect settings
Explanation: tolerances are provided to the parts because variations in the material properties introduce errors and production machines themselves have inherent inaccuracies. another reason to introduce tolerance is that it is not possible to make perfect settings by operator so some tolerances are provided.
9.

What is bilateral tolerance?

A. total tolerance is in 1 direction only
B. total tolerance is in both the directions
C. may or may not be in one direction
D. tolerance provided all over the component body
Answer» B. total tolerance is in both the directions
Explanation: total tolerance is specified on both the sides of the basic dimension. this usually have + and – tolerance of equal amount.
10.

What is mean clearance?

A. maximum size of hole minus maximum size of shaft
B. minimum size of hole minus minimum size of shaft
C. mean size of hole minus mean size of shaft
D. average of both size of shaft and hole
Answer» C. mean size of hole minus mean size of shaft
Explanation: statistical approach allows wider tolerances compared to complete interchangeability approach. methods used by statistical approach are usually permits cheaper production. mean clearance is equal to (mean size of hole – mean size of shaft).
11.

Which of the following is incorrect about tolerances?

A. too loose tolerance results in less cost
B. tolerance is a compromise between accuracy and ability
C. too tight tolerance may result in excessive cost
D. fit between mating components is decided by functional requirements
Answer» A. too loose tolerance results in less cost
Explanation: loose tolerance results in increase in cost, assembly problems and poor performance of the product. tight tolerance results in unnecessary machining and inspection time.
12.

Quality control charts doesn’t depend on which factor?

A. normal distribution
B. random sampling
C. independence between samples
D. binomial distribution
Answer» D. binomial distribution
Explanation: in establishing of realistic specifications, control charts are considered as a good guide for the design office. quality
13.

If a clearance fit is present between shaft and hole, what is the tolerance on shaft or hole for a complete interchangeable approach?

A. ½ of maximum clearance – ½ of minimum clearance
B. ¼ of maximum clearance – ¼ of minimum clearance
C. maximum clearance – minimum clearance
D. ¾ of maximum clearance – ¾ of minimum clearance
Answer» A. ½ of maximum clearance – ½ of minimum clearance
Explanation: there are two approaches for deciding of tolerances and shafts i.e. statistical and complete interchangeable approach. there is no risk is taken about a single non-conforming assembly in complete interchangeable approach.
14.

A beam is said to be of uniform strength, if

A. b.m. is same throughout the beam
B. shear stress is the same through the beam
C. deflection is the same throughout the beam
D. bending stress is the same at every section along its longitudinal axis
Answer» D. bending stress is the same at every section along its longitudinal axis
Explanation: beam is said to be uniform strength if at every section along its longitudinal axis, the bending stress is same.
15.

Stress in a beam due to simple bending is

A. directly proportional
B. inversely proportional
C. curvilinearly related
D. none of the mentioned
Answer» A. directly proportional
Explanation: the stress is directly proportional to the load and here the load is in terms of bending. so the stress is directly proportional to bending.
16.

Which stress comes when there is an eccentric load applied?

A. shear stress
B. bending stress
C. tensile stress
D. thermal stress
Answer» B. bending stress
Explanation: when there is an eccentric load it means that the load is at some distance
17.

On bending of a beam, which is the layer which is neither elongated nor shortened?

A. axis of load
B. neutral axis
C. center of gravity
D. none of the mentioned
Answer» B. neutral axis
Explanation: when a beam is in bending the layer in the direction of bending will be in compression and the other will be in tension. one side of the neutral axis will be shortened and the other will be elongated.
18.

The bending stress is  

A. directly proportional to the distance of layer from the neutral layer
B. inversely proportional to the distance of layer from the neutral layer
C. directly proportional to the neutral layer
D. does not depend on the distance of layer from the neutral layer
Answer» A. directly proportional to the distance of layer from the neutral layer
Explanation: from the bending equation m/i
19.

Consider a 250mmx15mmx10mm steel bar which is free to expand is heated from 15C to 40C. what will be developed?

A. compressive stress
B. tensile stress
C. shear stress
D. no stress
Answer» D. no stress
Explanation: if we resist to expand then only stress will develop. here the bar is free to expand so there will be no stress.
20.

The safe stress for a hollow steel column which carries an axial load of 2100 kN is 125 MN/m2. if the external diameter of the column is 30cm, what will be the internal diameter?

A. 25 cm
B. 26.19cm
C. 30.14 cm
D. 27.9 cm
Answer» B. 26.19cm
Explanation: area of the cross section of column = π/4 (0.302 – d2) m2
21.

Stress intensity factor is the critical value of stress at which crack extension occurs.

A. true
B. false
Answer» B. false
Explanation: stress intensity specifies the stress intensity at the tip of the crack.
22.

Fracture toughness does not depend upon geometry of the part containing crack

A. true
B. false
Answer» B. false
Explanation: fracture toughness is directly proportional to a factor y that depends upon geometry of the part having crack.
23.

How many modes are there for crack propagation?

A. 2
B. 3
C. 4
D. 5
Answer» B. 3
Explanation: opening, sliding and tearing are the 3 modes.
24.

A curved beam has neutral axis is curved while loaded and straight when unloaded.

A. true
B. false
Answer» B. false
Explanation: curved beam’s neutral axis is always curved irrespective of the loading.
25.

The bending stress in a straight beam varies linearly with the distance from neural axis like that in a curved beam.

A. true
B. false
Answer» B. false
Explanation: bending stress in a curved beam varies hyperbolically with the distance from neutral axis.
26.

1816mm and radius of centroidal axis is 100mm, then find the bending stress at inner fibre whose radius is 50mm. Area of cross section of beam is 7200mm² and the beam is loaded with 100kN of load.

A. 97.3
B. 95.8
C. 100.6
D. none of the mentioned
Answer» C. 100.6
Explanation: e=100-89.816=10.8184mm, h=89.1816-50=39.1816mm, m=100 x 100 n-
27.

1816/ [7200 x 10.8184 x 50] or σ=100.6N/mm².

A. 14.80mm
B. 13.95mm
C. 16.5mm
D. 17.2mm
Answer» B. 13.95mm
Explanation: σ(b)=mh/ aer or σ(b)=1000x4dx(4d-0.2d-3.5d)/ 0.8d²x0.02dx3.5d , σ(b)=21428.6/d²
28.

A curved beam with eccentricity 0.02D is loaded with 1kN.Centroidal radius=4D and inner and outer radii are 3.5D and 4.5D respectively. Area of cross section is 0.8D². Find the dimension D if allowable stress is 110N/mm² and considering only direct tensile stress.

A. 4.7mm
B. 6.8mm
C. 13.95mm
D. 3.4mm
Answer» D. 3.4mm
Explanation: direct tensile stress=1000/0.8d² or σ (t) =1250/d² 1250/d²=110 or d=3.4mm.
29.

All type of stresses vanishes after as soon as the applied load is removed.

A. true
B. false
Answer» B. false
Explanation: residual stresses are independent of the load.
30.

Residual stresses are always added in the load stresses and hence are always harmful.

A. true
B. false
Answer» B. false
Explanation: residual stresses may be beneficial when they are opposite to load stresses and hence are subtracted from load stresses.
31.

Which of the following is the numerator of factor safety formula?

A. working stress
B. shear stress
C. tensile stress
D. ultimate stress
Answer» D. ultimate stress
Explanation: factor of safety is defined as ratio of ultimate stress and working stress. it is also called as factor of ignorance. the factor of safety is dependent on the type of load.
32.

Which of the following can be the factor of safety for shock loading?

A. 11
B. 13
C. 4
D. 7
Answer» B. 13
Explanation: for shock loading, the range in which the factor of safety can lie is 12 to 15. therefore only 13 lies in that range and 11, 4, 7 are all values which are beyond that range.
33.

Factor of safety is used to find out the reliability of the design.

A. true
B. false
Answer» A. true
Explanation: factor of safety tells us about how much load the material can take before it fails. basically, it states the load carrying capacity of a material beyond the actual load.
34.

What can understand by the factor of safety equal to one?

A. it means that the structure will fail under load
B. it means that the structure will only support the actual load
C. it means that the structure will support more than the actual load
D. there is no relation between factor safety and load application
Answer» B. it means that the structure will only support the actual load
Explanation: when the factor of safety is one it means that the ultimate stress is equal to the working stress and therefore the body can only support load up to actual load and no more before failing.
35.

For which of the following design factor of

A. 0.1
B. 1
C. 2
D. 0.9
Answer» C. 2
Explanation: if the design factor of safety is not more than 1 then the design may not work and will fail under certain conditions.
36.

What is a safe factor of failure for a component which on failure can result in financial loss or serious injury?

A. 1
B. 2
C. 3
D. 4
Answer» D. 4
Explanation: for components which on failing can be hazardous and can lead to serious injuries, death and financial loss, the factor of safety should be taken equal to or more than 4.
37.

Design factor for most aircraft structures is 2.

A. true
B. false
Answer» B. false
Explanation: the design factor of safety for most aircraft structures or components is taken to be 1.5 and not 2. more factors affect this value, but it is most of the time taken as 1.5.
38.

Does ASME Standard take into consideration shock and fatigue factors?

A. yes
B. no
Answer» A. yes
Explanation: moment is multiplied by a number to consider these factors while designing the shaft.
39.

Calculate the tension in the rope of pulley C.

"The layout of a shaft supported on bearings at A & B is shown. Power is supplied by means of a vertical belt on pulley B which is then transmitted to pulley C carrying a horizontal belt. The angle of wrap is 180’ and coefficient of friction is 0.3. Maximum permissible tension in the rope is 3kN. The radius of pulley at B & C is 300mm and 150mm"

Calculate the tension in the rope of pulley C.

"The layout of a shaft supported on bearings at A & B is shown. Power is supplied by means of a vertical belt on pulley B which is then transmitted to pulley C carrying a horizontal belt. The angle of wrap is 180’ and coefficient of friction is 0.3. Maximum permissible tension in the rope is 3kN. The radius of pulley at B & C is 300mm and 150mm"
A. 6778.3n and 7765.3n
B. 5948.15n and 2288.75n
C. 5468.4n ad 8678.3n
D. none of the listed
Answer» B. 5948.15n and 2288.75n
Explanation: (p₃-p₄)x150=549.3×1000 and p₃/p₄=2.6. hence p₃=5948.15n and p₄=2288.75n.
40.

If bending moment on point B in horizontal plate is M and in vertical plane is m, then the net bending moment at point B is?

"The layout of a shaft supported on bearings at A & B is shown. Power is supplied by means of a vertical belt on pulley B which is then transmitted to pulley C carrying a horizontal belt. The angle of wrap is 180’ and coefficient of friction is 0.3. Maximum permissible tension in the rope is 3kN. The radius of pulley at B & C is 300mm and 150mm"

If bending moment on point B in horizontal plate is M and in vertical plane is m, then the net bending moment at point B is?

"The layout of a shaft supported on bearings at A & B is shown. Power is supplied by means of a vertical belt on pulley B which is then transmitted to pulley C carrying a horizontal belt. The angle of wrap is 180’ and coefficient of friction is 0.3. Maximum permissible tension in the rope is 3kN. The radius of pulley at B & C is 300mm and 150mm"
A. m
B. m
C. m+m
D. √m²+m²
Answer» D. √m²+m²
Explanation: the two moments act perpendicularly to each other.
41.

If yielding strength=400N/mm², the find the permissible shear stress according to ASME standards.

A. 72 n/mm²
B. 76 n/mm²
C. 268 n/mm²
D. 422 n/mm²
Answer» A. 72 n/mm²
Explanation: 0.18×400.
42.

The strength of hollow shaft is more than the strength of solid shaft of same weight.

A. true
B. false
Answer» A. true
Explanation: outer fibers are more effective in resisting the applied moments. in hollow shafts material is removed and spread on a larger radius.
43.

Solid shafts are used in epicyclic gearboxes.

A. true
B. false
Answer» B. false
Explanation: in epicyclic gears, one shaft rotates inside other and hence hollow shafts are used.
44.

Refer to fig
Two plates are fastened by means of two bolts.
The yield strength of bolt is 400N/mm² and factor of safety is 4.
Determine the size of the bolts.

Refer to fig 
Two plates are fastened by means of two bolts. 
The yield strength of bolt is 400N/mm² and factor of safety is 4. 
Determine the size of the bolts.
A. 8mm
B. 9mm
C. 10mm
D. 11mm
Answer» A. 8mm
Explanation: permissible hear stress=0.5 x 400 /4 =50n/mm². p=2 (π xd²/4) x τ or 5000=2 x π x d² x 50/4 or d=7.97mm.
45.

8’CW from the vertical. Hence net shear force = √ [5000cos36.8+1250]²+ [5000sin36.8]².

A. 10.74mm
B. 9.23mm
C. 11.54mm
D. 8.68mm
Answer» A. 10.74mm
Explanation: the maximum shear force to which any bolt is subjected is 6047.44n. hence 0.5 x 400/3= 4 x 6047.44/πd² or d=10.74mm.
46.

Which bolt is under maximum shear stress?

A. 1
B. 2
C. 3
D. all are under equivalent shear stress
Answer» C. 3
Explanation: primary shear force acts equally on the three bolts in the vertically upward direction while the moment is cw along cg so its effect on bolts will be acw. hence secondary shear force acts vertically upward on bolt 3 and vertically downward on bolt 1.
47.

Arrange the bolts in order of decreasing shear stresses.

A. 1>2>3
B. 2>1>3
C. 3>1>2
D. 3>2>1
Answer» D. 3>2>1
Explanation: on bolt 3,primary and secondary shear stress act in same direction, on bolt 2 there is no secondary shear stress and on bolt 1 the two act in opposite direction.
48.

Determine the size of the bolts if yield strength of bolt is 400N/mm² and factor of safety is 4. The bolts are equidistant having separated by 60mm and the margin to the left and right is 25mm. Also P=5kN acts at a distance of 200mm from the channel.

A. 14.34mm
B. 13.44mm
C. 15.44mm
D. 12.66mm
Answer» B. 13.44mm
Explanation: clearly bolt 3 is under maximum shear stress. net shear stress= primary shear stress + secondary shear stress or τ= (1000+6100) n or 0.5 x 400//4=7100 x
49.

A knuckle joint is unsuitable for two rotating shafts, which transmit torque

A. true
B. false
Answer» A. true
Explanation: knuckle joint can’t be used for torque transmission.
50.

A maximum of how many roads may be connected using a knuckle joint?

A. 2
B. 3
C. 4
D. 5
Answer» B. 3
Explanation: in rare explanation, two rods with forks and one rod with eye is connected.
51.

Which of the following are important parts of knuckle joint?

A. eye
B. pin
C. fork
D. each of the mentioned
Answer» D. each of the mentioned
Explanation: all the mentioned parts are important components of knuckle joint.
52.

Calculate the diameter of pin from shear consideration with maximum shear stress allowed is 40NN/mm² and an axial tensile force of 50kN is acting on the rod.

A. 39mm
B. 44mm
C. 49mm
D. 52mm
Answer» A. 39mm
Explanation: as the pin is subjected to double shear diameter (d) = √(2p/π x τ) = 38.80mm.
53.

A knuckle joint can be used in valve mechanism of a reciprocating engine.

A. yes
B. no
C. yes but there are stress probles
D. no as it is very dangerous to use
Answer» A. yes
Explanation: knuckle joint can be used till the rods coincide or intersect in a plane.
54.

Cotter joint is used when the members are subjected to which type of stresses?

A. axial tensile
B. axial compressive
C. axial tensile or compressive
D. none of the mentioned
Answer» C. axial tensile or compressive
Explanation: cotter joint is used when axial forces are applied.
55.

The principle of wedge action is used in cotter joint.

A. true
B. false
Answer» A. true
Explanation: wedge action imparts tightening to the cotter joint.
56.

Which of the following is not a part of cotter joint?

A. socket
B. spigot
C. cotter
D. collar
Answer» D. collar
Explanation: there is no point of mentioning collar alone in a cotter joint. it has to be a spigot collar or socket collar.
57.

Cold riveting holds the connected parts better than hot riveting.

A. true
B. false
Answer» B. false
Explanation: the compression of connected parts in hot riveting causes friction, which resist sliding of one part with respect to other. this force is greater in hot riveting.
58.

67 N/mm².; Spigot dia=65mm; thickness 0f collar=15mm

A. 131mm
B. 139mm
C. 141mm
D. 149mm
Answer» A. 131mm
Explanation: compressive stress= p/ [(socket dia-spigot dia)*thickness].
59.

Cotter joint can be used to connect two rods for torque transmission purpose.

A. true
B. false
Answer» B. false
Explanation: cotter joint is never used to connect two rods for torque transmission purpose.
60.

Thickness of plate is required more in welding than in riveting.

A. true
B. false
Answer» B. false
Explanation: in riveting, cross section is weakened due to the holes and to compensate this, thicker plates are required in riveting.
61.

The capacity of welded structures to damp vibrations is quite good.

A. true
B. false
Answer» B. false
Explanation: capacity of welded joints to damp vibrations is poor.
62.

Themit consists of a finely divided mixture of iron oxide and copper.

A. true
B. false
Answer» B. false
Explanation: thermite is a mixture of iron oxide and copper.
63.

Rails in the field are generally welded by using

A. thermit welding
B. gas welding
C. electric arc welding
D. forge welding
Answer» A. thermit welding
Explanation: wherever it is uneconomical to carry welding equipments, thermit welding is used.
64.

In gas welding which of the following is generally used?

A. oxygen-hydrogen
B. oxygen-acetylene
C. oxygen-hydrogen or oxygen-acetylene
D. none of the mentioned
Answer» C. oxygen-hydrogen or oxygen-acetylene
Explanation: intense heat is released i a controlled way and at a moderate temperature.
65.

Filler material is used in electric resistance welding.

A. yes
B. no filler material used
C. depends on the type of welding
D. none of the listed
Answer» B. no filler material used
Explanation: no filler material is used. only the heat released from resistance of metallic parts to current is used for melting the adjoining parts.
66.

Which type of welding is generally used in automobile sector?

A. electric arc welding
B. electric resistance welding
C. gas welding
D. forge welding
Answer» B. electric resistance welding
Explanation: electric resistance welding can
67.

Hard peening is

A. hammering the weld across the length while the joint is hot
B. hammering the weld along the length while the joint is hot
C. hammering the weld along the length while the joint is cold
D. hammering the weld across the length while the joint is cold
Answer» B. hammering the weld along the length while the joint is hot
Explanation: hammering is doe to relieve stresses and inducing compressive stresses to improve the fatigue strength of the joint.
68.

A rivet is specified as a 20mm rivet. What does it mean?

A. none of the mentioned
B. shank dia 20mm
C. head dia 20mm
D. both head and shank dia 20mm
Answer» B. shank dia 20mm
Explanation: terminology is this way.
69.

In hand riveting die is a part of hammer.

A. true
B. false
Answer» B. false
Explanation: die is a part of hammer in machine riveting.
70.

The amount by which the two rods to be joined are drawn together is called as?

A. draw
B. portray
C. lead
D. pitch
Answer» A. draw
Explanation: draw measures the amount of distance advancing after which spigot rests on socket.
71.

Two steel rods connected by cotter joint are subjected to 50 kN load each. What is the minimum diameter required of the rods? (Given: Yielding Stress= 400N/mm² ; Factor of Safety=6)

A. 31mm
B. 35mm
C. 36mm
D. 40mm
Answer» A. 31mm
Explanation: d=√(4p/πσ) where σ= yielding stress/f.s ; d=30.90mm or 31 mm.
72.

Among punching and drilling, which is cheaper?

A. punching
B. drilling
C. equally expensive
D. cannot be determined
Answer» A. punching
Explanation: drilling has more accuracy and is more expensive.
73.

Riveting is not recommended for aluminium alloys.

A. true
B. false
Answer» B. false
Explanation: aluminium alloys have poor weldability and hence riveting is preferred.
74.

In joining steel plate and asbestos, welding is preferred over riveting.

A. true
B. false
Answer» B. false
Explanation: riveting is preferred in joining heterogeneous materials.
75.

Quality checking of riveted joint is much expensive than that of welded joint.

A. true
B. false
Answer» B. false
Explanation: in welding, inspections like radiographic inspections are quite costly.
76.

In which of the following bonding theory, water molecules break down to form H+ and OH- ions?

A. electrostatic bonding theory
B. hot strength theory
C. surface tension theory
D. block and wedge theory
Answer» A. electrostatic bonding theory
Explanation: in electrostatic bonding theory, water is mixed in clay and sand grains, these water molecules then break into h+ ions and oh– ions.
77.

What does the clay particle absorb in electrostatic bonding theory?

A. complete water
B. h+ ions
C. oh–ions
D. sand grains
Answer» C. oh–ions
Explanation: the oh– ions are basically the base ions. the clay particles in electrostatic bonding theory, absorb the oh– ions because of the not satisfied valence bond.
78.

For bonding action of clays, what is the amount of water needed?

A. 1.5%-8%
B. 3.5%-11%
C. 4.5%-12%
D. 5.5%-13%
Answer» A. 1.5%-8%
Explanation: for the bonding action of the clays, water is needed, which activates the
79.

What is the amount of sea coal needed in cast irons for large green casting moulding sands?

A. 10%
B. 15%
C. 20%
D. 25%
Answer» A. 10%
Explanation: sea coal otherwise is used in small numbers for binding. sea coal is used for surface appearance improvement. it is used about 10% in cast iron moulding sands for large green casting sands.
80.

Pitch maybe used up to what percent?

A. 1%
B. 2%
C. 3%
D. 4%
Answer» B. 2%
Explanation: pitch distillation of soft coals plays a vital role in bonding theory. pitch is used for getting a good surface finish on iron casts. these pitches generally are used up to be to 2%.
81.

Which of the following increases the dry strength of the sand?

A. iron oxides
B. fuel oils
C. cereals
D. dextrin and molasses
Answer» D. dextrin and molasses
Explanation: dextrin and molasses are used for increasing the dry strength of the sand, which add hardness to the mould.
82.

Cereals improve flowability and lower collapsibility.

A. true
B. false
Answer» B. false
Explanation: cereals do not improve flowability, as a matter of fact, it reduces it, and, cereals are not known to reduce or not the collapsibility, in fact it is known to improve it.
83.

How much should fuel oil be added to increase the moulding ability of sand?

A. 0.01% – 0.1%
B. 0.02% – 0.2%
C. 0.03% – 0.3%
D. 0.04% – 0.4%
Answer» A. 0.01% – 0.1%
Explanation: fuel oils are known to have great properties in them. fuel oils are helpful in adding to the increase of the moulding
84.

Which of the following function can the spring perform?

A. store energy
B. absorb shock
C. measure force
D. all of the mentioned
Answer» D. all of the mentioned
Explanation: spring can easily perform all the listed functions.
85.

The helix angle is very small about 2⁰. The spring is open coiled spring.

A. yes
B. it is closed coiled spring
C. that small angle isn’t possible
D. none of the listed
Answer» B. it is closed coiled spring
Explanation: when the helix angle is small, the plane containing each coil is almost at right angles and hence it is called closed coiled spring.
86.

The helical spring ad wire of helical torsion spring, both are subjected to torsional shear stresses.

A. true
B. false
Answer» B. false
Explanation: the wire of helical torsion sprig is subjected to bending stresses.
87.

Multi leaf springs are not recommended for automobile and rail road suspensions.

A. true
B. false
Answer» B. false
Explanation: they are highly used in automobile and rail road suspensions.
88.

The spring index is the ratio of wire diameter to mean coil diameter.

A. true
B. false
Answer» A. true
Explanation: it is the ratio of mean coil diameter to wire diameter.
89.

If spring index=2.5, what can be concluded about stresses in the wire?

A. they are high
B. they are negligible
C. they are moderate
D. cannot be determined
Answer» A. they are high
Explanation: if indexis <3 then stresses are high due to curvature effect.
90.

A spring with index=15 is prone to buckling.

A. true
B. false
Answer» A. true
Explanation: due to large variation, such a spring is prone to buckling.
91.

If number of coils are 8 and wire diameter of spring 3mm, then solid length is given by?

A. none of the listed
B. 27mm
C. 24mm
D. 21mm
Answer» C. 24mm
Explanation: solid length=8×3.
92.

Compressed length is smaller than the solid length.

A. true
B. false
Answer» B. false
Explanation: compressed is length of spring under maximum compressive force. there is some gap between the coils under maximum load.
93.

Pitch of coil is defined as axial distance in compressed state of the coil.

A. yes
B. it is measured in uncompressed state
C. it is same in uncompressed or compressed state
D. none of the listed
Answer» B. it is measured in uncompressed state
Explanation: pitch is measured in uncompressed state.
94.

The maximum fluctuation of speed is the

A. difference of minimum fluctuation of speed and the mean speed
B. difference of the maximum and minimum speeds
C. sum of the maximum and minimum speeds
D. variations of speed above and below the mean resisting torque line
Answer» B. difference of the maximum and minimum speeds
Explanation: the difference between the maximum and minimum speeds during a cycle is called the maximum fluctuation of speed.
95.

In a turning moment diagram, the variations of energy above and below the mean resisting torque line is called

A. fluctuation of energy
B. maximum fluctuation of energy
C. coefficient of fluctuation of energy
D. none of the mentioned
Answer» A. fluctuation of energy
Explanation: the fluctuation of energy may be determined by the turning moment diagram for one complete cycle of operation.the variations of energy above and below the mean resisting torque line are called fluctuation of energy.
96.

The ratio of the maximum fluctuation of energy to the ……. is called coefficient of fluctuation of energy.

A. minimum fluctuation of energy
B. workdone per cycle
C. maximum fluctuation of energy
D. none of the mentioned
Answer» B. workdone per cycle
Explanation: the difference between the maximum and the minimum energies is known as maximum fluctuation of energy.
97.

Due to the centrifugal force acting on the rim, the flywheel arms will be subjected to

A. tensile stress
B. compressive stress
C. shear stress
D. none of the mentioned
Answer» A. tensile stress
Explanation: the tensile stress in the rim due to the centrifugal force, assuming that the rim is unstrained by the arms, is determined in a similar way as a thin cylinder subjected to internal pressure.
98.

The cross-section of the flywheel arms is usually

A. elliptical
B. rectangular
C. i-section
D. l-section
Answer» A. elliptical
Explanation: the cross-section of the arms is usually elliptical with major axis as twice the minor axis.
99.

In order to find the maximum bending moment on the arms, it is assumed as a

A. simply supported beam carrying a uniformly distributed load over the arm
B. fixed at both ends
C. cantilever beam fixed at the hub and carrying a concentrated load at the free end of the rim
D. none of the mentioned
Answer» C. cantilever beam fixed at the hub and carrying a concentrated load at the free end of the rim
Explanation: due to the torque transmitted from the rim to the shaft or from the shaft to the rim, the arms will be subjected to bending, because they are required to carry the full torque load. in order to find out the maximum bending moment on the arms, it may be assumed as a cantilever beam fixed at the hub and carrying a concentrated load at the free end of the rim.
100.

The diameter of the hub of the flywheel is usually taken

A. equal to the diameter of the shaft
B. twice the diameter of the shaft
C. three times the diameter of the shaft
D. four times the diameter of the shaft
Answer» B. twice the diameter of the shaft
Explanation: the diameter of hub is usually taken as twice the diameter of shaft and length from 2 to 2.5 times the shaft diameter. it is generally taken equal to width of the rim.
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