**Solved Paper Junior Engineer (JE) Mechanical 2018**

**Series: A**

**Post Code: 696**

**Note:** Answers are given according to the official provisional answer key. Give us feedback in the comment section, if any question is answered wrong.

1. The initial tension (in newton) in a bolt used for making a fluid tight joint like steam engine cover joints is calculated by which of the following relation in which ‘d’ is the nominal diameter of bolts in mm.

- 1420 d
- 1680 d
- 2080 d
**2840 d**

2. Welding takes place by

**Coalescence between the parts to be joined**- Surface joining the parts to be united by fusion of the filler rod.
- Surface tension between two parts
- None of these

3. The core diameter of the thread is equal to which of the following in which ‘d’ is the diameter of the bolt?

- 58 d
- 68 d
**84 d**- 94 d

4. Square thread is usually found on

- Spindle of bench vice
- Railway carriage couplings
**Feed mechanism of machine tools**- Screw outline lathes

5. The unit of modulus of elasticity is same as those of

- Stress, strain and pressure
- Stress, force and modulus of rigidity
- Strain, force and pressure
**Stress, pressure and modulus of rigidity**

6. The shear force of a cantilever beam of length ‘l’ carrying a uniformly distributed load of wper unit length is—————-at the free end

**Zero**- Wl/4
- Wl/2
- Wl

7. The hoop stress in a thin cylindrical shell is

- Longitudinal stress
- Compressive stress
- Radial stress
**Circumferential tensile stress**

8. According to Euler’s column theory, the crippling load for a column of length ‘l’ hinged at both end is

**Pie2El/l2**- Pie2El/4l2
- 4pieEl/l2
- 2pie2El/l2

9. The assumption made in Euler’s column theory is that

- The failure of the column occur due to buckling alone
- The length of the column is very large as compared to its cross-section dimensions
- the column material obeys Hook’s law
**All of these**

10. Euler’s column formula holds good for

- Short columns
**Long columns**- Both short and long columns
- Weak columns

11. A column is said to be short column, when

- Its length is very small.
- Its cross-sectional area is small
**The ratio of its length to the least radius of gyration is less than 80**- The ratio of its length to the least radius of gyration is more than 80.

12. The material in which the atoms are arranged chaotically is called

**Amorphous material**- Mesomorphous material
- Crystalline material
- None of these

13. The material in which the atoms are arranged regularly in some directions but not in orders is called

- Amorphous material
**Mesomorphous material**- Crystalline material
- None of these

14. The purpose of heat treatment is to

- Relieve the stresses set up in the material after hot or cold working
- Modify the structure of the material
- Change the grin size
**Any one of these**

15. A perfect black body is one which

- Is black in colour
**Absorbs heat radiations of all wavelengths falling on it**- Reflects all the heat radiations
- Transmits the heat radiations

16. The unit of Stefan-Boltzmann constant is

- Watt/mK
- Watt/m2K2
**Watt/m2K4**- Watt/mK2

17. Reynold number is the ratio of

- Energy transferred by convection to that by conduction
- Kinematic viscosity to the thermal conductivity
**Inertia force to viscous force**- None of these

18. The specific gravity of water is

- 0.001
- 0.01
- 0.1
**1**

19. The specific weight of water the S.I. units is taken as

- 81kN/m3
- 81 * 10^3N/m3
- 81 * 10^-6 N/mm3
**Any one of these**

20. The by-pass factor of a cooling coil decrease with:

**Decrease in fin spacing and increase in number of rows**- Increase in fin spacing and increase in number of rows
- Increase in fin spacing and decrease in number of rows
- Decrease in fin spacing and decrease in number of rows

21. During heating and dehumidification process dry bulb temperature

- Remain constant
**Increase**- Decrease
- None of these

22. The centrifugal compressors are generally used for refrigerants that require

- Smaller displacements and low condensing pressures
- Large displacements and high condensing pressures
- Small displacements and high condensing pressure
**Large displacements and low condensing pressures**

23. The mass per unit volume of a liquid at a standard temperature and pressure is called

- Specific volume
**Mass density**- Specific gravity
- None of these

24. The intensity of pressure at any point in a liquid is

- Directly proportional to the area of the vessel containing liquid
**Directly proportional to the depth of the liquid from the surface**- Directly proportional to the length of the vessel containing liquid
- Inversely proportional to the depth of the liquid from the surface

25. The Bernoulli’s equation based upon the assumption that

- There is no loss of energy of the liquid flowing
- The velocity of flow is uniform across any cross-section of the pipe
- No force except gravity acts on the fluid
**All of these**

26. Overall efficiency of a centrifugal pump is the ratio of

- Energy available at the impeller to the energy supplied to the pump by the prime mover
**Actual work done by the pump to the energy supplied to the pump by the prime mover**- Energy supplied to the pump to the energy available at the impeller
- Manometric head to the energy supplied by the impeller per kN of water

27. The centrifugal tension in the belts

- Increases power transmitted
- Decrease power transmitted
**Have no effect of power transmitted**- Increase power transmitted upto a certain speed and then decrease

28. The maximum fluctuation of energy is the

**Difference between the maximum and minimum energies**- Sum between the maximum and minimum energies
- Variations of energies above and below the mean resisting torque line
- Ratio of the mean resisting torque to the work done per cycle

29. Watts governor can work satisfactorily at speed from

**60 to 80 r.p.m.**- 80 to 100 r.p.m
- 100 to 200 r.p.m
- 200 to 300 rpm

30. In the law of machine p=mw +C

- C stand for velocity ratio
- M stands for friction
**C stands for friction**- M stands for velocity ratio

31. According to Lami’s theorem

- The three forces must be equal
- The three forces must be at 120 degree to each other
- The three forces must be in equilibrium
**If the three forces acting at a point are in equilibrium, then each force is proportional to the sine of the angle between the other between the other two.**

32. The centre of gravity of a quadrant of a circle lies along its central radius at a distance of

- 0.3 R
**0.424 R**- 0.5 R
- 0.6 R

33. The co-efficient of friction is the

- Angle between normal reaction and the resultant of normal reaction and the limiting force
**Ration of limiting friction and normal reaction**- The friction force acting when the body is just about to move
- The friction force acting when the body is in friction

34. If the arm of couple is doubled, then moment of that couple would

- Remains the same
**Be doubled**- Be halved
- None of these

35. Two equal force are acting at a point with an angle of 60 degree between them the resultant is 50under root3 N, the magnitude of each force will be

- 100 N
- 150 N
**50 N**- 50 Underroot 3 N

36. When trying to turn a key into the lock. Which of the following is applied?

- Coplanar forces
- Non-coplanar forces
- Moment
**Couple**

37. A body weighing 200 N is placed on a rough horizontal plane. If the value of co-efficient of friction is 0.6 then the normal reaction will be

- 120 N
**200 N**- 150 N
- 300 N

38. Gear lapping is an operation

- For gear reconditioning
**After heat treatment**- Prior to heat treatment
- None of these

39. Thermoplastic materials are those materials which

- Are formed into shape under heat and pressure and result in permanently hard product
**Do not become hard with the application of heat and pressure and no chemical change occurs**- Are flexible and can withstand wear under suitable conditions
- Are used as a friction lining for clutches and break

40. The stiffness of closed coil helical spring is given by S, such that S is equal to

**Cd4/64.R4.n**- Cd3/64.R4.n
- Cd4/64.R3.n
- Cd4/36.R4.n

41. A solid shaft 160 mm diameter is used to transmit the torque. The maximum shear stress induced is 50 N/mm2 , the maximum torque the shaft can transmit is

**128 * 10^5 pie N**- 128 * 10^3 pie N
- 128 * 10 ^7 pie N
- 28 * 10^5 pie N

42. The maximum stress induced due to suddenly applied is —————— the stress induced when the same load is applied gradually.

- Same
**Twice**- thrice
- None of these

43. Moment of inertia of a circular section is

**Πd^4/64**- Πd^4/16
- Πd^3/64
- None of these

44. The bending moment of a simply supported beam of length ‘l’ carrying point load ‘W’ at the mid is equal to

**Wl2/4**- Wl/4
- Wl/64
- Wl/16

45. The factor of safety depends upon

- Nature of loading
- Frequency of variation of load
- Degree of reliability required
**All of these**

46. The force is completely defined when we specify its

- Magnitude
- Direction
- Point of application
**All of these**

47. Dynamic friction as compared to static is

- Same
- More
**Less**- Has no correction

48. The setting of tools in advance at a far from the machine tool or off-line in special holders is known as

- Qualified tools
- Semi-qualified tools
**Pre-set tools**- All of these

49. CAPP in CNC Machines and Automation stand for

- Computer Aided Personnel Programming
- Computer Aided private Programming
**Computer Aided Part programming**- All of these

50. A Nozzle is said to divergent nozzle

**When the cross-section of the nozzle increases continuously from an entrance to exit**- When the cross-section of the nozzle decrease continuously from entrance to exit
- When the cross-section of the nozzle first decreases from entrance to throat and then increases its throat to exit
- None of these

51. The objective of caulking in a riveted joint is to make the joint

- Free from corrosion
- Stronger in tension
- Free from stresses
**Leak-proof**

52. The centre distance between two consecutive rivets in a row is called

- Back pitch
- Margin
**Pitch**- Diagonal pitch

53. The margin “m” in the rivet is given by

**m=m 1.5 d**- m=1.75 d
- m=1d
- m=2d

54. The transverse fillet weld is designed for:

**Tensile strength**- Compressive strength
- Bending strength
- Shear strength

55. A cotter is used to transmit

- Axial tensile load only
- Axial compressive load only
- Combined axial and twisting loads
**Axial tensile and compressive loads**

6-7 wrong answer in key