Kerala PSC Mechanical Engineering Previous Question Paper – 078/2015

The Commission publishes this paper without an answer key, so no answers are shown.

1. Which one of the following cast irons consists of carbon in rosette form?

2. The specific speed of a centrifugal pump depends on the

4. Match the following metal forming processes with their associated stresses in the work piece.
Metal forming process Type of force

5. Measurement of very small displacements

6. Avrefrigerator and a heat pump operate between the same temperature limits. The coefficient
of performance of the pump is 4, Then COP of the refrigerator will be

7. An adiabatic process is the one in which

8. Asingle stage rocket is launched vertically from rest with its thrust programmed to give the
rocket.a constant upward acceleration of 5 m/s®. If the fuel is exhausted 10 seconds after the
launch, the maximum altitude reached by the rocket

9. The power transmitted by the belt is maximum when the relation between maximum tension (T) and centrifugal tension (T꜀) is:

10. Cold working is carried out at

11. Ina binary alloy system of A and B liquid phase of 40% A (60%

12. In machining a job on a shaper ram makes 40 strokes per minute and the length of the stroke
is 150 mm. Calculate the cutting speed.

13. Which one of the following is a stress relieving treatment?

14. A solid shaft resists a bending moment of 3 kN-m and a twisting moment of 4 kN-m together,
then maximum torque that can be applied is

15. The thermal gradient in a heat generating cylinder under steady conduction at half the
radius location will be

16. An Operating Characteristics (OC) is a plot between

17. An external gear with 120 teeth meshes with a pinion of 80 teeth module being 6 mm. What
is the center to center distance in mm?

18. A hydraulic turbine develops 1500 kW under a head of 50 m, If the head is reduced to 25 m
the power developed in kW is

19. The actual demand of the product is 65, the previous year’s forecast is 60 and the value of
smoothing 0.3, what would be the forecast for the current year using exponential smoothing
method of forecasting?

20. Shrinkage allowance is provided in the pattern to compensate for shrinkage when

21. Match the following –
Equipment Parameter measured
A. Diffraction grating 1, Small angular deviations on long flat surfaces
B. Optical flat 2. On-line measurement of moving part
C. Auto collimator 3. Measurement of gear pitch
D. Laser sean micrometer 4. Surface texture using interferometry

22. Reynolds's number is the ratio of inertia force to

23. The percentage change in cutting speed required to give 50% reduction in tool life when
n= 0.25 is

24. In arc welding process an increase in the arc length

25. A domestic refrigerator is loaded with food and the door closed. During a certain period the
machine consumes 1 kWhr of energy and the internal energy of the system drops by 5000 kJ.
Find the net heat transfer of the system

26. The operation of enlarging a hole is called
~

27. Ina fuel cell electricity is produced by

28. In transonic regime Mach number is between

29. Ifthe arrival takes place every 10 minutes with a service time of 4 minutes per unit, then the
mean arrival rate, mean service rate and the probability one would have to wait will be
respectively

30. Oil flows through a 200 mm diameter horizontal cast iron pipe, friction factor f =0.0225 at a
rate of flow 0.2 m/s. What is the length of the pipe if head loss due to friction is 118.16 m of
the oil? g=9.81m/s”?

31. A leather belt 9 mm x 250 mm is used to drive a cast iron pulley 900 mm in diameter at 336
rpm. If the active arc on the smaller pulley is 120° and the stress in tight side is 2 MPa, find
the power capacity of the belt. The density of leather may be taken as 980 kg/m$ and the
coefficient of friction of leather on cast iron is 0.35.

33. A Diesel engine has a compression ratio of 14 and cut-off takes place at 6% of the stroke. Find
the air standard efficiency.

34. A 400 kg diesel engine mounted on a chassis frame runs at 500 rpm. The static deflection of
the weigh is 2.4 mm. The reciprocating parts have a mass of 18 kg. The stroke of the engine
is 160 mm. The damping coefficient of the dash pot attached is 2 N/mm/s. Determine the
amplitude at steady state and the resonance speed

35. Acantilever of length ‘7, moment of inertia ‘f and Young’s modulus ‘Ff carries a concentrated
load W at the middle of its length. Calculate the slope of the cantilever at the free end.

37. A boiler produces 2000 kg of dry and saturated steam per hour at 10 bar and feed water is
heated by an economizer to a temperature of 110°C. 225 ke coal of a calorific value of
30100 kJ/kg are fired per hour. If 10% of coal remains unburnt find the thermal efficiency of
the boiler. Enthalpy of dry saturated steam at 10 bar is 2776.2 k J/kg.

38. A damped vibrating system consists of a mass of 8 kg which makes 30 oscillations in
18 seconds. After 5 oscillations, the amplitude reduced to 0.25 times the initial value.
Determine the spring stiffness, logarithmic decrement, damping coefficient and damping
factor. :

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82. A component is subjected to completely reversed stress cycle which varies over a 30 second
time period, as follows :

10 cycles at 500 MPa

5 cycles at 600 MPa

3 cycles at 700 MPa 7

The corresponding fatigue lives for the above stresses are 10°, 4×10* and 1.5 x 10* cycles
respectively. Determine the fatigue life of the component. :

86. A person of mass 80 kg and another person of 60 kg stand side by side at the same end of a
130 kg boat, ready to dive each with a velocity of 5 m/s relative to the boat. Determine the
velocity of the boat after they have both dived. Assume that the 80 kg person dives first.