Multiple choice question for engineering
Set 1
1. Which of the following are true for copper alloys
a) Posses excellent thermal and electrical conductivity
b) Can be easily cast and machined
c) Has good corrosion resistance
d) All of the mentioned
Answer
Answer: d [Reason:] Properties of copper.
2. Which of the following contain copper
a) bronze
b) gunmetal
c) monel metal
d) each of the mentioned
Answer
Answer: d [Reason:] All the mentioned alloys contain copper to some extent.
3. Which of the following are true
a) Brass is costlier then copper
b) Brass has excellent corrosion resistance
c) Brass has good machinability
d) Brass has poor thermal conductivity
Answer
Answer: b [Reason:] Brass is a good thermal conductor,is cheaper and has poor machinability.
4. As the amount of zinc increases
a) strength of brass increases and ductility decrease
b) strength of brass increases and ductility increase
c) strength of brass decreases and ductility increases
d) strength of brass decreases and ductility decreases
Answer
Answer: a [Reason:] Brass contains zinc and copper. Zinc affects strength with direct increase in strength with increase of zinc content.
5. Which of the following are true for aluminium bronze
a) contain 5-10% aluminium
b) excellent corrosion and is also called imitation gold
c) difficult to cast
d) all of the mentioned
Answer
Answer: d [Reason:] Color of aluminium bronze is similar to gold. Other two are the properties of alloys.
6. Which of the following statements for phosphorus bronze is true?
a) contains 0.2% phosphorus
b) phosphorus increases tensile strength
c) use for worm wheels and bearings
d) all of the mentioned
Answer
Answer: d [Reason:] It has good tensile strength, corrosion resistance and is used for bearings.
7. Gunnmetal is an alloy of copper which __ % tin and __% zinc.
a) 10,2
b) 2,10
c) 4,5
d) 5,4
Answer
Answer: a [Reason:] Zinc is used to improve fluidity during casting and hence is kept lesser than tin.
8. Monel metal is a copper nickel alloy of __% nickel and __%copper.
a) 32,65
b) 65,32
c) 20,80
d) 80,20
Answer
Answer: b [Reason:] Composition.
9. Which of the following are true for die casting alloys?
a) this process consists of forcing the molten metal into a closed metal die
b) process used for a metal with low melting point
c) surface finish is excellent
d) all of the mentioned
Answer
Answer: d [Reason:] Characteristics of die casting alloys.
Set 2
1. 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
Answer: c [Reason:] Cotter joint is used when axial forces are applied.
2. The principle of wedge action is used in cotter joint.
a) True
b) False
Answer
Answer: a [Reason:] Wedge action imparts tightening to the cotter joint.
3. Can the cotter joint be used to connect slide spindle and fork of valve mechanism?
a) True
b) False
Answer
Answer: a [Reason:] As long as axial forces act, cotter joint can be employed.
4. Which of the following is not a part of cotter joint?
a) Socket
b) Spigot
c) Cotter
d) Collar
Answer
Answer: d [Reason:] There is no point of mentioning collar alone in a cotter joint. It has to be a spigot collar or socket collar.
5. Cold riveting holds the connected parts better than hot riveting.
a) True
b) False
Answer
Answer: b [Reason:] 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.
6 .In cold riveting like hot riveting shank is subjected to majorly tensile stress.
a) True
b) False
Answer
Answer: b [Reason:] In cold riveting there is no reduction in length and hence no tensile stress. Shear stress dominates.
7. Determine the width of the cotter used in cotter joint connecting two rods subjected to axial load of 50kN and permissible shear stress in cotter is 50N/(mm² ). Given thickness of cotter=10mm
a) 5omm
b) 100mm
c) 150mm
d) 25mm
Answer
Answer: a [Reason:] Cotter is subjected to double shear hence width=P/(2*τ*t).
8. If joint is to fail by crushing of socket collar then estimate the diameter of socket collar. Given Permissible compressive stress= 126.67 N/mm².; Spigot dia=65mm; thickness 0f collar=15mm
a) 131mm
b) 139mm
c) 141mm
d) 149mm
Answer
Answer: a [Reason:] Compressive stress= P/ [(socket dia-spigot dia)*thickness].
9. Cotter joint can be used to connect two rods for torque transmission purpose.
a) True
b) False
Answer
Answer: b [Reason:] Cotter Joint is never used to connect two rods for torque transmission purpose.
10. Thickness of plate is required more in welding than in riveting.
a) True
b) False
Answer
Answer: b [Reason:] In riveting, cross section is weakened due to the holes and to compensate this, thicker plates are required in riveting.
Set 3
1. A coupling is a mechanical device that temporarily joins two rotating shafts to each other.
a) True
b) False
Answer
Answer: b [Reason:] A coupling permanently joins two rotating shafts.
2. In distortion energy theorem, if a unit cube is subjected to biaxial stress, then S(yt) is given by which of the following?
a) √ (σ₁²- σ₁σ₂ +σ₂²)
b) σ₁²- σ₁σ₂ +σ₂²
c) √ (σ₁²+ σ₁σ₂ +σ₂²)
d) σ₁²+ σ₁σ₂ +σ₂²
Answer
Answer: a [Reason:] S(yt)=√[(σ₁ -σ₂)²+(σ₂ -σ₃)²+(σ₃ -σ₁)²]/2, for σ₃=0; expression a is obtained.
3. Oldham coupling i used to connect two shafts having intersecting axes.
a) True
b) False
Answer
Answer: b [Reason:] Oldham coupling is used to connect two parallel shafts separated by a small distance.
4. A machine started malfunctioning due to some issues with the coupling. The coupling emplaced in the machine was Oldham. The only coupling available in the workshop is Hooke’s coupling. So Oldham coupling can be replaced by Hooke’s coupling.
a) True
b) False
Answer
Answer: b [Reason:] It is not possible to replace Oldham by Hooke’s coupling as Hooke’s is used to connect intersecting axes and not parallel axes shafts.
5. A muff coupling is connecting two shafts. The torque involved is 650N-m. The shaft diameter is 45mm with length and breadth of the key being 14mm and 80mm respectively. Find the shear stress induced in the key.
a) 30.2N/mm²
b) 25.8N/mm²
c) 34.4N/mm²
d) None of the listed
Answer
Answer: b [Reason:] τ =2M/dbl.
6. The region of safety for biaxial stresses is of which shape in the case of maximum distortion energy theorem.
a) Ellipse
b) Circle
c) Rectangle
d) Square
Answer
Answer: a [Reason:] S(yt)= √ (σ₁²- σ₁σ₂ +σ₂²) or S²(yt)= (σ₁²- σ₁σ₂ +σ₂²). This is an equation of ellipse.
7. Distortion energy theorem is not recommended for ductile materials.
a) True
b) False
Answer
Answer: b [Reason:] Experimental investigations have shown that distortion energy theorem gives good results for failure of ductile component.
8. Among maximum shear stress theory and distortion energy theory, which gives the higher value shear yield strength?
a) Maximum shear stress theory
b) Distortion energy theory
c) Both give equal values
d) Vary from material to material
Answer
Answer: b [Reason:] Maximum shear stress theory gives S(sy)=0.5S(yt) while Distortion energy theorem gives S(sy)=0.577(Syt).
9. A muff coupling is connecting two shafts. The torque involved is 650N-m. The shaft diameter is 45mm with length and height of the key being 14mm and 80mm respectively. Find the compressive stress induced in the key.
a) 70.1 N/mm²
b) 51.6N/mm²
c) 45.5N/mm²
d) None of the listed
Answer
Answer: b [Reason:] σ=4M/dhl.
Set 4
1. Stressed parts are always kept in tension.
a) True
b) False
Answer
Answer: a [Reason:] Cast iron has more compressive strength.
2. Shot blasting process improves the endurance limit of the component.
a) True
b) False
Answer
Answer: a [Reason:] Shot blasting employs throwing wheel which imparts strength to the material.
3. Which process allows controlling grain structure of the product?
a) Casting
b) Forging
c) None of the mentioned
d) Die Casting
Answer
Answer: b [Reason:] In casting metal is in fluid state and hence impossible to control the grain structure.
4. While designing a forging, the profile is selected such that the fibrous lines are parallel to the tensile forces and perpendicular to shear forces.
a) True
b) False
Answer
Answer: a [Reason:] Tensile load is applied parallel to the grain structures.
5. Cast surfaces have good finishing.
a) True
b) False
Answer
Answer: b [Reason:] Cavity is surrounded by sand and hence not good finish is obtained.
6. In forging, metal is in which of the following stage?
a) Elastic
b) Plastic
c) Can be in any stage
d) Rigid
Answer
Answer: b [Reason:] Forging is the working of metal in plastic range.
7. Forged components can be held between close limits.
a) True
b) False
Answer
Answer: a [Reason:] There is no shrinkage problems and hence less tolerances.
8. 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
Answer: c [Reason:] Machining each part is very time consuming.
9. In manual assembly, cost of screw is higher than the cost of driving a screw.
a) True
b) False
Answer
Answer: b [Reason:] Generally manufacturing screw is cheaper than driving it.
10. Maximum carbon content in welding is usually limited to
a) 0.22%
b) 0.8%
c) 1.5%
d) 2%
Answer
Answer: a [Reason:] With increase of carbon, welding becomes difficult as weld becomes susceptible to cracks.
Set 5
1. If a spring has plain ends then number of inactive coils is?
a) 1
b) 2
c) 3
d) 0
Answer
Answer: d [Reason:] There are no inactive coils in plain ends.
2. Spring having square ends has 1 inactive coil.
a) True
b) False
Answer
Answer: b [Reason:] There are 2 inactive coils.
3. Martin’s factor compensates for curvature effect in springs.
a) True
b) False
Answer
Answer: b [Reason:] Wahl’s factor accommodates curvature effect while designing spring.
4. The angle of twist for the equivalent bar to a spring is given by? (Symbols have their usual meaning)
a) 8PD²N/Gd⁴
b) 16PD²N/Gd⁴
c) 16PDN/Gdᵌ
d) 8PDN/Gdᵌ
Answer
Answer: b [Reason:] θ=Ml/GJ where M=PD/2, l=πDN and J=πd⁴/32.
5. The axial deflection of spring for the small angle of θ is given by?
a) 328PDᵌN/Gd⁴
b) 8PDᵌN/Gd⁴
c) 16PDᵌN/Gd⁴
d) 8PD²N/Gdᵌ
Answer
Answer: b [Reason:] Deflection=θxD/2.
6. A spring of stiffness constant k is cut in two equal parts. The stiffness constant of new spring will be k/2.
a) True
b) False
Answer
Answer: b [Reason:] k=Gd⁴/8DᵌN, hence k is inversely proportional to number of coils. Thus result will be 2k.
7. For two spring connected in series, the force acting on each spring is same and equal to half of the external force.
a) True
b) False
Answer
Answer: b [Reason:] Te force on each spring is equal to the external force.
8. For two springs connected in series, the net deflection is equal to the sum of deflection in two springs.
a) True
b) False
Answer
Answer: a [Reason:] The net deflection is sum of the deflection of sprigs connected in series.
9. For two springs connected in parallel, net force is equal to the sum of force in each spring.
a) True
b) False
Answer
Answer: a [Reason:] Net force applied is distributed in the two springs.
10. Patenting is defined as the cooling below the freezing point of water.
a) True
b) False
Answer
Answer: b [Reason:] Patenting is heating steel above critical range followed by rapid cooling.
11. Find the Wahl’s factor if spring index is 6.
a) 1.2020
b) 1.2424
c) 1.2525
d) 1.5252
Answer
Answer: c [Reason:] K=[4C-1/4C-4]+0.615/C.
12. Find the shear stress in the spring wire used to design a helical compression sprig if a load of 1200N is applied on the spring. Spring index is 6, and wire diameter 7mm.
a) 452.2N/mm²
b) 468.6N/mm²
c) 512.2N/mm²
d) None of the listed
Answer
Answer: b [Reason:] τ=K x 8PC/πd² where K=[4C-1/4C-4]+0.615/C.
13. Find the mean coil diameter of a helical compression sprig if a load of 1200N is applied on the spring. Spring index is 6, and wire diameter 7mm.
a) 7/6mm
b) 42mm
c) 1200×6/7 mm
d) None of the listed
Answer
Answer: b [Reason:] D=Cd.
14. Find total number coils in a spring having square and ground ends. Deflection in the spring is 6mm when load of 1100N is applied. Modulus of rigidity is 81370N/mm². Wire diameter and pitch circle diameter are 10mm and 50mm respectively.
a) 7
b) 6
c) 5
d) 4
Answer
Answer: a [Reason:] Deflection=8PDᵌN/Gd⁴ or N=4.4 or 5. Total coils=5+2(square grounded ends).
15. A railway wagon moving with a speed of 1.5m/s is brought to rest by bumper consisting of two springs. Mass of wagon is 100kg. The springs are compressed by 125mm. Calculate the maximum force acting on each spring.
a) 1200N
b) 1500N
c) 1800N
d) 2000N
Answer
Answer: c [Reason:] mv²/2=Pxdeflection/2.