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# (Download) AFCAT Question Papers - 02/2015, Engineering Knowledge Test (EKT) (Booklet Series-E) (Mechanical Stream)

## (Download) AFCAT Question Papers - 02/2015, Engineering Knowledge Test (EKT)

## Booklet Series-E (Mechanical Stream)

**INSTRUCTIONS FOR CANDIDATES**

1. Total number of Questions 50. Each Question carries three marks.

2. One mark will be deducted for every wrong answer.

3. No mark will be deducted for un-attempted questions.

**Q1. Three houses are available in a locality. Three persons apply for the houses. Each applies for one house without consulting others. The probability that all the three apply for the same house is**

(a) 2/9 (b) 1/9 (c) 8/9 (d) 7/9

**Q2. If the area of the square is increased by 69% the side of the square increases by**

(a) 13% (b) 30% (c) 39% (d) 130%

**Q3. A can solve 90% of the problems given in a book and B can solve 70%. What is the probability that at least one of them will solve a problem, selected at random from the book?**

(a) 0.16 (b) 0.63 (c) 0.97 (d) 0.20

**Q4. An unbiased die with faces marked 1, 2, 3, 4, 5 and 6 is rolled four times. Out of four face values obtained, the probability that the minimum face value is not less than 2 and the maximum face value is not greater than 5 is**

(a) 16/81 (b) 1/81 (c) 80/81 (d) 65/81

**Q5. The projection of a vector on another vector is**

(a) scalar (b) vector

(c) neither vector not scalar (d) either scalar or vector

**Q6. During the execution of a CNC part program block NO20 GO2 X45.0 Y25.0 R5.0 the type of tool motion will be**

(a) circular Interpolation — clockwise (b) circular Interpolation — counter-clockwise

(c) linear Interpolation (d) rapid feed

**Q7. A component can be produced by any of the four processes I, II, III and IV. Process I has a fixed cost of Rs 20 and variable cost of Rs 3 per piece. Process II has a fixed cost of Rs 50 and variable cost of Re 1 per piece. Process III has a fixed cost of Rs 40 and variable cost of Rs 2 per piece. Process IV has a fixed cost of Rs 10 and variable cost of Rs 4 per piece. If the company wishes to produce 100 pieces of the component, from economic point of view it should choose **

(a) Process I (b) Process II (c) Process III (d) Process IV

**Q8. When a conductor cuts magnetic flux, an emf is induced in the conductor. This is known as**

(a) Joule's law (b) Faraday's law (c) Coulomb's law (d) Ampere's law

**Q9. X-rays are used for the study of crystal structure because**

(a) X-rays are completely absorbed by the crystal

(b) the wavelength of X-ray is of the same order of magnitude in the inter-atomic spacing in crystals

(c) the wavelength of X-rays is very small in comparison with the inter-atomic spacing in crystals

(d) the crystals are completely transparent to X-rays

**Q10. A radioactive isotope has a half-life of 10 days. If today there are 125 g of it left, what was its original weight 40 days earlier?**

(a) 600 g (b) 1000 g (c) 1250 g (d) 2000 g

**Q11. A tensile test is performed on a mild steel round bar. Its diameter after fracture will**

(a) remain same (b) increase

(c) decrease (d) depend upon rate of loading

**Q12. In an interchangeable assembly, shafts of size 25.000±0.040mm mate with holes of size 25.000±0.020 mm. The maximum possible clearance in the assembly will be**

(a) 10 microns (b) 20 microns

(c) 30 microns (d) 60 microns

**Q13. The neutral axis of a beam is subjected to __________ stress.**

(a) zero (b) maximum tensile

(c) minimum tensile (d) maximum compressive

**Q14. When a load on the free end of a cantilever beam is increased, failure will occur**

(a) at the free end (b) at the fixed end

(c) in the middle of the beam (d) at a distance 2/3 from free end

**Q15. In PERT analysis a critical activity has**

(a) maximum float (b) zero float

(c) maximum cost (d) minimum cost

**Q16. The capacity of a strained body for doing work on the removal of the straining force, is called**

(a) strain energy (b) resilience

(c) proof resilience (d) impact energy

**Q17. The hoop stress in a thin cylindrical shell is**

(a) longitudinal stress (b) compressive stress

(c) radial stress (d) circumferential tensile stress

**Q18. The ratio of specific weight of a liquid to the specific weight of pure water at a standard temperature is called**

(a) density of liquid (b) specific gravity of liquid

(c) compressibility of liquid (d) surface tension of liquid

Q19. The purpose of a surge tank is

(a) to control the pressure variations due to rapid changes in the pipe line flow

(b) to eliminate water hammer possibilities

(c) to regulate flow of water to turbines by providing necessary retarding head of water

(d) all of the above

**Q20. The S-N curve for steel becomes asymptotic nearly at**

(a) 103 cycles (b) 104 cycles

(c) 106 cycles (d) 109 cycles

**Q21. The divergent portion of a venturimeter is made longer than convergent portion in order to**

(a) avoid the tendency of breaking away the stream of liquid

(b) to minimise frictional losses

(c) both (a) and (b)

(d) none of these

**Q22. Silicon in cast iron**

(a) makes the iron soft and easily machinable

(b) increases hardness and brittleness

(c) makes the iron white and hard

(d) aids fusibility and fluidity

**Q23. The process which improves the machinability of steels, but lowers the hardness and tensile strength, is**

(a) normalising (b) full annealing

(c) process annealing (d) spheroidising

**Q24. The malleability is the property of a material by virtue of which a material**

(a) regains its shape and size after the removal of external forces

(b) retains the deformation produced under load permanently

(c) can be drawn into wires with the application of a tensile force

(d) can be rolled or hammered into thin sheets

**Q25. A ladder is resting on a rough ground and leaning against a smooth vertical wall. The force of friction will act**

(a) downward at its upper end (b) upward at its upper end

(c) zero at its upper end (d) perpendicular to the wall at its upper end

**Q26. Water at 42°C is sprayed into a stream of air at atmospheric pressure, dry bulb temperature of 40°C and a wet bulb temperature of 20°C. The air leaving the spray humidifier is not saturated. Which of the following statements is true?**

(a) Air gets cooled and humidified (b) Air gets heated and humidified

(c) Air gets heated and dehumidified (d) Air gets cooled and dehumidified

**Q27. The efficiency of a lifting machine is the ratio of**

(a) output to the input

(b) work done by the machine to the work done on the machine

(c) mechanical advantage to the velocity ratio

(d) all of the above

**Q28. A lot has 10% defective items. Ten items are chosen randomly from this lot. The probability that exactly 2 of the chosen items are defective is**

(a) 0.0036 (b) 0.1937 (c) 0.2234 (d) 0.3874

**Q29. The gas in cooling chamber of a closed cycle gas turbine is cooled at**

(a) constant volume (b) constant temperature

(c) constant pressure (d) none of these

**Q30. Which of the following is the correct statement?**

(a) For a given compression ratio, both Otto and Diesel cycles have the same efficiency.

(b) For a given compression ratio, Otto cycle is more efficient than Diesel cycle.

(c) For a given compression ratio, Diesel cycle is more efficient than Otto cycle.

(d) The efficiency of Otto or Diesel cycle has nothing to do with compression ratio.