Mechanical Engineering- Solved

1. The resultant force acting on a body will be zero if the body

(a) Rotate with uniform deceleration

(b) Rotate with uniform acceleration

(c) Does not rotate

(d) Rotates

Ans: (c)

2. The movement of a force

(a) Occurs about a point

(b) Measures the capacity to do useful work

(c) Occurs only when bodies are in motion

(d) Measures the ability to produce turning or twisting about an axis

Ans: (d)

3. After reaching the yielding stage while testing a mild steel specimen strain

(a) Becomes constant

(b) Strain start decreasing

(c) Increasing without any increase in load

(d) Non of the above

Ans: (c)

4. Volumetric strain for a rectangular of length L, breadth B, and thickness T subjected to a pull of P is given by

(a) e (1-2m)

(b) e (1-2/m)

(c) e (m-2)

(d) e (2/M-1)

Ans: (b)

5. The mechanism used in petrol engine is

(a) Crank mechanism

(b) Slider mechanism

(c) Slider crank mechanism

(d) Natural lines and circular

Ans: (c)

6. M 10 screws have a pitch of

(a) 0.5 mm

(b) 1.25 mm

(c) 2.50 mm

(d) 5.00 mm

Ans: (b)

7. A coarse screw of major diameter 6.00 mm and pitch is designated as

(a) 1x6M

(b) Coarse M 6

(c) M 6

(d) 6Mx6x1

Ans: (c)

8. Longitudinal vibration are set to occur when the particles of a body moves.

(a) Perpendicular to its axis

(b) Parallel to its axis

(c) In a circle about its axil

(d) None of these

Ans: (b)

9. A mass of 1 Kg is attached to the end of a sprig with stiffness 0.7 N/mm.. The critical damping coefficient of the system is

(a) 1.40 Ns/m

(b) 18.522 Ns/m

(c) 52.92 Ns/m

(d) 529.20 Ns/m

Ans: (c)

10. An ideal fluid is

(a) Similar to a perfect gas

(b) Friction less and incompressible

(c) One which obeys Newtons laws of viscosity

(d) One which satisfies continuity equation

(e) One which flows through pipes with least friction

Ans: (b)

11. The stress Strain relation of the Newtonian fluids is

(a) Linear

(b) Parabolic

(c) Hyperbolic

(d) Involutic

Ans: (a)

12. The Reynolds No. may be defined as the ration of

(a) Viscous forces to inertial forces

(b) Elastic forces to pressure forces

(c) Viscous forces to gravity forces

(d) None of the above

Ans: (d)

13. All heat transfer processes

(a) Involve transfer of energy

(b) Involve temperature difference between the bodies

(c) Obeys the first law of the thermodynamics

(d) Obeys second law of thermodynamics

Ans: (b)

14. Which insulating material is a suitable low temperature application?

(a) Cork

(b) Asbestos paper

(c) Diatomaceous earth

(d) 85 % magnesia

Ans: (c)

15. A heat exchanger that can remove fix quantity of heat form a system is available where should it be installed for best economy

(a) Prior to first stage compression

(b) As intercooler

(c) After final stage compression

(d) Depends upon size of installation

Ans: (a)

16. The performance of air compressor at high altitudes as compared to that at sea level will be

(a) Better

(b) Same

(c) Inferior

(d) Will depend upon temperature of air

Ans: (c)

17. Which is incorrect?

(a) Compression ration= Initial volume +final Volume

(b) Final pressure= Initial Pressure x Compression ration

(c) Initial pressure= Final pressure+Compression ration

(d) None of the above

Ans: (d)

18. During adiabatic compression

(a) No heat leaves or enters the system

(b) Maximum work is done

(c) Specific heat remains constant

(d) Temperature remains constant

Ans: (a)

19. In multistage turbines by introducing reheating

(a) Thermal efficiency improves

(b) The output of turbine increases

(c) Work done by compressor reduces

(d) The ratio compressor work/turbine decreases

Ans: (a)

20. In Jet engine the compression ration

(a) Varies with altitude

(b) Varies with square of speed

(c) Varies as cube of speed

(d) remains constant

Ans: (b)

21. An axial flow compressor has

(a) Larger blade at gas entry and smaller blades at exit

(b) Smaller blade at gas entry and larger blades at exit

(c) Identical blades at exit as well as entry

(d) Size of blades remains same only angles changes

Ans: (a)

22. An axial flow compressor is suitable for

(a) High volume flow rates with a small pressure rise

(b) High volume flow rate with high pressure rise

(c) Low volume flow rates with low pressure rise

(d) Low volume flow rates with high pressure rise

Ans: (c)

23. Thermal efficiency of a gas turbine cycle can be improved by

(a) Reheating between the expansion stage

(b) Intercooling between compression stages

(c) Regeneration

(d) Any of the above

Ans: (d)

24. Gas turbine used in aircraft is of

(a) Open cycle type

(b) Closed cycle type with reheating

(c) Closed cycle type with reheating and regeneration

(d) Open cycle type with reheating, regeneration and intercooling

Ans: (a)

25. In a nozzle under choked flow conditions pressures waves travel, in the divergent portion, at

(a) Subsonic speed

(b) Sonic speed

(c) Super sonic

(d) Subsonic to supersonic speed

Ans: (b)

26. In a nozzle if back pressure is equal to inlet pressure

(a) No flow occurs

(b) Maximum flow occurs

(c) Flow is subsonic in diverging section

(d) Flow is supersonic in convergent section as well as supersonic section

Ans: (b)

27. The flow on two sides of a normal shock wave is

(a) Subsonic

(b) Sonic

(c) Supersonic

(d) Supersonic on one side and subsonic on the other side

Ans: (d)

28. The diverging portion of the nozzle acts as a diffuser for

(a) Subsonic flow

(b) Supersonic flow

(c) Both the subsonic as well as supersonic flow

(d) None of the above

Ans: (a)

29. Identify the correct statement

(a) All materials undergo plastic deformation

(b) A completely brittle material would not fracture at elastic limit

(c) Brittleness is an important engineering consideration, because it allows the material to be redistribute localize stresses.

(d) A metal which is brittle in tension may be ductile under hydro static compression

Ans: (d)

30. The defect responsible for the phenomenon of slip by which most metals deform plastically, is known as

(a) Fracture

(b) Twining

(c) Dislocation

(d) Strain hardening

Ans: (c)

31. Fatigue failure occurs when a part is subjected to

(a) Tensile stress

(b) Compressive stress

(c) Torsion

(d) Fluctuating stress

Ans:(d)

32. Stress concentration occurs when

(a) A body is subjected to excessive stress

(b) A body is subjected to unidirectional stress

(c) A body is subjected to fluctuating stress

(d) A body is subjected to non uniform stress distribution

Ans: (d)

33. Stress concentration may be caused by

(a) Change in cross sectional area

(b) Change in shape

(c) Change in dimension

(d) A hole or a notch in the body

Ans:(d)

34. The inability of a body to change its state of rest or uniform motion along a straight line is called its

(a) Momentum

(b) Velocity

(c) Acceleration

(d) Inertia

Ans: (d)

35. A material subjected to reversal of stresses does not fail at a stress known as

(a) fatigue stress

(b) Proof stress

(c) Safe stress

(d) Endurance stress

Ans: (d)