Mechanical Model paper

1. The figure shows a pin-jointed plane truss loaded at the point M by hanging a mass of 100 kg. The member LN of the truss is subjected to a load of?
(a) 0 Newton
(b)490 Newton in compression
(c)981 Newton in compression
(d) 981 Newton in tension

2. In terms of. Poisson’s ratio (v) the ratio of Young’s Modulus (E) to Shear Modulus (G) of elastic materials is?
(a) 2(1 + v) (b) 2(1 — v) (c) (1 + v)/2 (d) (1 — v)/2

3. Two mating spur gears have 40 and 120 teeth respectively. The pinion rotates at 1200 rpm and transmits a torque of 2O N. m. The torque transmitted by the gear is
(a) 6.6 Nm (b) 20 Nm (c) 40 Nm (d) 60 Nm

4. A vibrating machine is isolated from the floor using springs. If the ratio of excitation frequency of vibration of machine to the natural frequency of the isolation system is equal to 0.5, the transmissibility of ratio of isolation is?
(a)1/2 (b)3/4 (c)4/3 (d)2

5. The S-N curve for steel becomes asymptotic nearly at
(a)10 3 cycles (b) 10 4 cycles (c)10 6 cycles (d) 10 9 cycles
6. In the window air conditioner, the expansion device used is
(a)capillary tube (b) thermostatic expansion valve
(c)automatic expansion valve (d) float valve

6. During chemical de-humidification process of air
(a) dry bulb temperature and specific humidity decrease
(b) dry bulb temperature increases and specific humidity decreases
(c) dry bulb temperature decreases and specific humidity increases
(d) dry bulb temperature and specific humidity increase

7.An incompressible fluid (kinematic viscosity, 7.4 x 10-7 m2 /s, specific gravity, 0.88) is held between two parallel plates. If the top plate is moved with a velocity of 0.5 rn/s while the bottom one is held stationary, the fluid attains a linear velocity profile in the gap of 0.5 mm between these plates; the shear stress in Pascal on the surface of top plate is ?
(a)0.651 x 10 -3    (b) 0.651 (c)6.51 (d) 0.651 x 103

8. Environment friendly refrigerant R134a is used in the new generation domestic refrigerators. Its chemical formula is ?
(a)CH Cl F2 (b) C2 Cl 3F3  (c)C2 Cl2F4 (d) C2 H2F4

9. The mechanism of material removal in EDM process is
(a) Melting and Evaporation
(b) Melting and Corrosion
(c) Erosion and Cavitation
(d) Cavitation and Evaporation

10. Two 1 mm thick steel sheets are to be spot welded at a current of 5000 A. Assuming, effective resistance to be 200 micro-ohms and current flow time of 0.2 second, heat generated during the process will be
(a)0.2 Joule (b) 1 Joule (c)5 Joule (d) 1000 Joules
21. In PERT analysis a critical activity has
(a)maximum Float (b) zero Float (c)maximum Cost (d) minimum Cost

11. For a product, the forecast and the actual sales for December 2002 were 25 and 20 respectively. If the exponential smoothing constant (a) is taken as 0.2, the forecast sales for January 2003 would be ?
(a)21 (b)23 (c)24 (d) 27

12. Misrun is a casting defect which occurs due to
(a) very high pouring temperature of the metal
(b) insufficient fluidity of the molten metal
(c) absorption of gases by the liquid metal
(d) improper alignment of the mould flasks

13. The percentage of carbon in gray cast iron is in the range of
(a)0.25 to 0.75 percent (b) 1.25 to 1.75 percent
(c)3 to 4 percent (d) 8 to 10 percent

Source: Nandi Group