Solved Question Paper for Foreman (Mechanical) in Ministry of Defence, Junior Scientific Officer (Mechanical) in Ministry of Defence, Assistant Executive Engineer (Mechanical), Additional Assistant Director (Safety) (Mechanical), Senior Scientific Assistant (Mechanical), Ministry of Defence & Junior Works Manager (Mechanical), Ministry of Defence conducted by UPSC

41. Consider the following statements with regard to reheat Rankine cycle:

1. All the steam is taken out of the turbine after partial expansion for reheating at constant volume

2. The cycle permits the use of very high pressure without excessive moisture at condenser inlet

3. The efficiency of the reheat cycle may or may not exceed that of a simple cycle operating between the same maximum temperature and pressure

4. If the reheat pressure is more than 80% of the maximum system pressure, the thermal efficiency will be more than that for a simple cycle

Which of the above statements are correct?

(a) 2, 3 and 4 only

(b) 1 and 2 only

(c) 1, 3 and 4 only

(d) 1, 2, 3 and 4

Answer: (a)

42. A cam-and-follower system with the follower having a constant velocity is not suitable in practice because

1. The cam rotates with a uniform angular velocity

2. The follower moves with constant velocity

3. Inertial forces are large at the beginning as well as at the end of follower motion

Which of the above statements is/are correct?

(a) 1 only

(b) 2 only

(c) 3 only

(d) 1, 2 and 3

Answer: (c)

43. 

(a) 500 𝑁.𝑚

(b) 1000 𝑁.𝑚

(c) 3000 𝑁.𝑚

(d) 5000 𝑁.𝑚

Answer: (b)

44. For a Hartnell governor, the loads on the spring at the lowest and highest equilibrium speeds are 1150 𝑁 and 85 𝑁, respectively. If the lift of the governor is 1.5 c.m , then spring stiffness would be

(a) 700 N/cm

(b) 710 N/cm

(c) 725 N/cm

(d) 690 N/cm

Answer: (b)

45. The direction of motion of the driven gear of a simple gear train having an odd number of idler gears will be

(a) Same as that of the driving gear

(b) Opposite to that of the driving gear

(c) Dependent upon the number of teeth on the driving gear

(d) Dependent upon the number of teeth on the driven gear

Answer: (a)

46. A fixed gear having 200 teeth meshes with another gear having 50 teeth. The two gears are connected by an arm. The number of turns made by the smaller gear for one revolution of the arm about the centre of the bigger gear is

(a) 8

(b) 7

(c) 6

(d) 5

Answer: (d)

47. Gears with involute profile have become popular in comparison to those with cycloidal profiles because:

1. They are interchangeable

2. They are insensitive to centre-distance variation

3. Involute rack cutter is straight-sided

4. They occupy lesser space

Which of the above statements are correct?

(a) 1 and 2 only

(b) 2 and 3 only

(c) 3 and 4 only

(d) 1 and 4 only

Answer: (b)

48. In case of two meshing gears both with involute tooth profiles, contact is made when the tip of the:

(a) Driven wheel touches the flank of a tooth of the driving wheel

(b) Driven wheel touches the face of a tooth of the driving wheel

(c) Driving wheel touches the face of a tooth of the driven wheel

(d) Driving wheel touches the flank of a tooth of the driven wheel

Answer: (a)

49. A spur gear with 32 teeth and module 4 mm is rotating at 400 rpm . The circular pitch is:

(a) 7 𝜋 𝑚𝑚

(b) 6 𝜋 𝑚𝑚

(c) 5 𝜋 𝑚𝑚

(d) 4 𝜋 𝑚𝑚

Answer: (d)

50. The coefficient of fluctuation of speed for a flywheel is defined as

(a) The ratio of the maximum fluctuation of speed to the mean speed

(b) The ratio of the mean speed to the maximum fluctuation with speed

(c) Difference between the maximum and minimum speeds during a complete cycle

(d) The square root of product of the maximum and minimum speeds during a complete cycle

Answer: (a)

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