LPSC Technical Assistant Mechanical Previous Year Paper 2020
| Sr.No. | Questions |
| 1 | An elastic rod, 30 cm long, of negligible weight hangs downwards from a support. In one case load is applied on rod 20 cm below the support and in the other case the same load is applied at bottom of rod. The reactions as supports will be
(a) More in first case (b) Same in both the cases (c) More in second case (d) None of the above |
| 2 | A solid shaft can resist a bending moment of 6kN-m and a torque of 8kN-m applied together. The maximum torque that the shaft can resist when applied alone is
(a) 10kN-m (b) 14kN-m (c) 7kN-m (d) 5kN-m |
| 3 | When a weight of 500 N falls on a spring of stiffness 0.5kN/m from a height of 2 mtr. What is the maximum deflection caused in first fall?
(a) 2 mtr (b) 4 mtr (c) 1 mtr (d) 0.63 mtr |
| 4 | If A is mxn matrix such that AB and BA both are defined, then B is a matrix of order
(a) n x n (b) m x m (c) m x n (d) n x m |
| 5 | Open cycle gas turbine works on
(a) Ericsson cycle (b) Rankine cycle (c) Carnot cycle (d) Brayton cycle |
| 6 | In steam nozzle, the inlet pressure of superheated steam is 10 bar. The exit pressure is decreased from 3 bar to 1 bar. The discharge rate will
(a) Remain constant (b) Decrease (c) Increase slightly (d) Increase or decrease depending on whether nozzle is convergent or divergent |
| 7 | For a closed system, the difference between the heat added to the system and the work done by the system is equal to
(a) Enthalpy (b) Entropy (c) Temperature (d) Internal Energy |
| 8 | Considering the variation of static pressure and absolute velocity in an impulse steam turbine, across one row of moving blades
(a) Both pressure and velocity decreases (b) Pressure remains constant, while velocity decreases (c) Pressure decreases while velocity increases (d) Pressure remains constant while velocity increases |
| 9 | If a ladder of 10 m long reaches a window 8 m above the ground, then the distance of the foot of the ladder from the base of the wall is
(a) 18 m (b) 8 m (c) 4 m (d) 6 m |
| 10 | The length, Young’s modulus and coefficient of thermal expansion of bar ‘A’ are twice that of bar ‘B’. What will be the ratio of stress developed in bar ’A’ to that in ‘B’ if the temperature of both bar is increased by same amount (both ends are constrained).
(a) 2 (b) 8 (c) 4 (d) 16 |
| 11 | Maximum shear stress developed on the surface of solid circular shaft under pure torsion is 400 MPa. If shaft diameter is doubled, then the maximum shear stress developed corresponding to the same torque will be
(a) 200 Mpa (b) 1600 Mpa (c) 100 Mpa (d) 50 Mpa |
| 12 | A steel bar of 20 mm x 20mm square cross-section is subjected to an axial compressive load of 200 kN. If the length of the bar is 1 m and E=100 GPa, the elongation of the bar will be
(a) 0.2 mm (b) 5 mm (c) 2.5 mm (d) 0.5 mm |
| 13 | A solid circular shaft of 20 mm diameter transmit a torque of 1570 Nm. The value of maximum shear stress developed is nearly
(a) 1000 Mpa (b) 20 MPa (c) 50 GPa (d) 20 GPa |
| 14 | Shock resisting steels should have
(a) Low wear resistance (b) Low hardness (c) Low tensile strength (d) Toughness |
| 15 | Dye penetrant method is generally used to locate
(a) Core defects (b) Surface defects (c) Superficial defects (d) Temporary defects |
| 16 | The ductility of a material with work hardening
(a) Increases (b) Remains unaffected (c) Decreases (d) Unpredictable |
| 17 | Eutectic reaction of Iron-Carbon occurs at
(a) 527 degree Celsius (b) 723 degree Celsius (c) 1493 degree Celsius (d) 1147 degree Celsius |
| 18 | For a fully developed laminar flow of water (dynamic viscosity 0.001 Pa-s) through a pipe of radius 10 cm, the axial pressure gradient is -10 Pa/m. The magnitude of maximum velocity (in m/s) is
(a) 25 (b) 50 (c) 75 (d) 100 |
| 19 | The viscosity in a fluid is caused mainly by
(a) Intermolecular force of cohesion (b) Molecular momentum exchange (c) Both (a) & (b) (d) None of the above |
| 20 | Falling drops of water becomes sphere due to the property of
(a) Surface tension (b) Adhesion (c) Cohesion (d) Viscosity |
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