Top Mechanical Objective Questions

Top Mechanical Objective Questions

1. A hollow shaft of same cross-section area as solid shaft transmits

A. Same torque

B. Less torque

C. More torque

D. Unpredictable

Answer: B. Less torque

2. In a cantilever beam, maximum deflection occurs at where

A. Bending moment is zero

B. Bending moment is maximum

C. Shear force is zero

D. Slope is zero

Answer: A. Bending moment is zero

3. In a rectangular beam, when width, depth and length are doubled, the bending stress will be

A. Shall remain unchanged

B. Shall be doubled

C. Shall become ¼ th

D. Shall be halved

Answer: C. Shall become ¼ th

4. In an I –section beam, the bending moment is resisted mainly by

A. Flanges only

B. Web only

C. Both by flanges and web

D. None of the above

Answer: B. Web only

5. In internal combustion (I.C.) engines, combustion of fuel takes place in

A. Outside the cylinder

B. Inside the cylinder

C. Not in the cylinder

D. None of the above

Answer: B. Inside the cylinder

6. Power available at the shaft of an I.C engine is known is

A. Brake horse power

B. Indicated horse power

C. Net indicated horse power

D. Pumping power

Answer: A. Brake horse power

7. In internal combustion engine piston the maximum temperature occurs at

A. Ring section

B. Gungeon pin

C. Bottom centre

D. Top centre

Answer: A. Ring section

8. A two-stroke engine is generally preferred to a four-stroke engine because

A. It offers low fuel consumption

B. It gives lesser shocks and vibrations

C. It can be easily started

D. It has smaller size for the same output.

Answer: D. It has smaller size for the same output.

9. During idling process, a petrol engine requires

A. Lean mixture

B. Rich mixture

C. Variable mixture

D. None of above

Answer: A. Lean mixture

10. Cavitation in a pipe will begin when

A. Pressure at any location reaches pressure equal to the saturated vapour pressure of liquid

B. Pressure becomes more than critical pressure

C. Flow is increased

D. Pressure is increased

Answer: A. Pressure at any location reaches pressure equal to the saturated vapour pressure of liquid

11. Capillary action of liquid is due to the

A. Viscosity of liquid

B. Cohesion of liquid particles

C. Surface tension

D. Adhesion of liquid particles on the surface

Answer: B. Cohesion of liquid particles

12. In one ton refrigeration machine, the term “one ton” implies

A. One ton refrigerant is used

B. One ton water can be converted into ice

C. One ton ice when melts from and at 0oC in 24 hours, the refrigerating effects is equivalent to 3000 kcal/hour

D. None of the above

Answer: C. One ton ice when melts from and at 0oC in 24 hours, the refrigerating effects is equivalent to 3000 kcal/hour

13. In a refrigeration cycle, the moisture content is to be removed before it enters into which system

A. Cold side of system

B. Evaporator

C. compressor

D. condenser

Answer: B. Evaporator

(1) Pitot tube is used for measurement of

(a) Pressure

(b) Temperature

(d) Velocity

Ans.: (d) Velocity

(2) Slow plastic deformation of material under constant stress is

(a) Creep

(b) Fatigue

(d) Elastic deformation

Ans.: (a) Creep

(3) Mass balancing is done to

(a) Avoid flutter

(b) Increase bending stress

(d) Distributing mass on control surface

Ans.: (a) Avoid flutter

(4) Short columns are preferred over long columns from

(a) Strength consideration

(b) Buckling consideration

(d) None of the above

Ans.: (b) Buckling consideration

(5) Centre of pressure of an aerofoil with an increase of angle of attack will

(a) Move forward

(b) Move backward

(d) None of the above

Ans.: (a) Move forward

(6) Thermal efficiency of a gas turbine plant as compared to diesel engine plant

(a) Higher

(b) Lower

(d) May be higher or lower

Ans.: (a) Higher

(7) A closed cycle gas turbine works on

(a) Carnot cycle

(b) Rankine cycle

(d) Atkinson cycle

Ans.: (c) Joule cycle

(8) A bolt of uniform strength can be developed by

(a) Keeping the core dia of threads equal to the dia of unthreaded portion of bolt

(b) Keeping the core dia of threads smaller than the dia of unthreaded portion of bolt

(d) None of the above

Ans.: (a) Keeping the core dia of threads equal to the dia of unthreaded portion of bolt

(9) Stress concentration factor is defined as ratio of

(a) Max stress to endurance limit

(b) Nominal stress to endurance limit

(d) Nominal stress to max stress

Ans.: (c) Max stress to nominal stress

(10) Principle effect of humidity is

(a) Corrosion

(b) Leaking from sealed enclosures

(d) Differential contraction of metal parts

Ans.: (a) Corrosion

(11) Backlash is

(a) Sum of the clearance of two gears

(b) Mutual play between two gears

(d) Any of the above

Ans.: (c) Amount by which the width of a tooth space exceeds the thickness of the engaging tooth on pitch circle

(12) Teflon is used for bearings because of

(a) Low co-efficient of friction

(b) Better heat dissipation

(d) All of the above

Ans.: (a) Low co-efficient of friction

(13) When two elastic bodies collide with each other

(a) Two bodies will momentarily come to rest after collision

(b) The two bodies tend to compress & deform at the surface of contact

(d) All of the above

Ans.: (d) All of the above

(14) Antifriction bearings are

(a) Thick lubricated bearing

(b) Thin lubricated bearing

(d) Plastic bearing

Ans.: (c) Ball & roller bearing

(15) What is Hertzian stress?

(a) Tensile stress on inner surface of cylinder

(b) Bending stress on two contact surface

(d) Shear stress on two contact surfaces

Ans.: (c) Contact stress on two contact surfaces

(16) Mohr’s circle can be used to determine following stress on inclined surface

(a) Principal stresses

(b) Normal stresses

(d) All of the above

Ans.: (a) Principal stresses

(17) What size of material required for making rolled threads?

(a) Pitch diameter

(b) Root diameter

(d) None

Ans.: (a) Pitch diameter

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