MECHANICAL ENGINEERING QUESTIONS

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 Newtons in compression
(c)981 Newtons in compression
(d) 981 Newtons 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. The figure shows the state of stress at a certain point in a stressed body. The magnitudes of normal stresses in the x and y direction are 100 MPa and 20 MPa respectively. The radius of Mohr’s stress circle representing this state of stress is

(a)120
(b)80
(c)60
(d)40
5.For a mechanism shown below, the mechanical advantage for the given configuration is?

(a)0
(b) 0.5
(c)1.0
(d)Infinity

6.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
7. A torque of 10 Nm is transmitted through a stepped shaft as shown in figure.

The torsional stiffnesses of individual sections of lengths MN, NO and OP are 20 Nm/rad 30 Nm/rad and 60 Nm respectively. The angular deflection between the ends M and P of the shaft is?
(a) 0.5 rad
(b) 1.0 rad
(c) 5.0 rad
(d) 10.0 rad

8.

9. 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
10. In the window air conditioner, the expansion device used is
(a)capillary tube
(b) thermostatic expansion valve
(c)automatic expansion valve
(d) float valve
11. 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
12.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 Pascals on the surface of top plate is ?
(a)0.651 x 10 ^-3
(b) 0.651
(c)6.51
(d) 0.651 x 10³

13.Environment friendly refrigerant R134_a is used in the new generation domestic refrigerators. Its chemical formula is ?
(a)CH Cl F₂
(b) C₂ Cl ₃F₃
(c)C₂ Cl ₂F₄
(d) C₂ H₂F₄
14.

(a)x—2y=0
(b) 2x+y=0
(c)2x—y=0
(d) x+2y=0

15. A gas contained in a cylinder is compressed, the work required for compression being 5000 kJ. During the process, heat interaction of 2000 kJ causes the surroundings to the heated. The change in internal energy of the gas during the process is
(a)—7000kJ
(b) —3000kJ
(c)+ 3000 kJ
(d) + 7000 kJ

16.The compression ratio of a gas power plant cycle corresponding to maximum work output for the given temperature limits of T_min and T_max will be

17.
(a)10 microns
(b) 20 microns
(c)30 microns
(d) 60 microns

18.

(a) circular Interpolation — clockwise
(b) circular Interpolation — counterclockwise
(c) linear Interpolation
(d) rapid feed
19. 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
20. 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
22. 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
23. 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
24. 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
25.In the figure shown,

the relative velocity of link1 with respect to link 2 is 12 m/sec. Link 2 rotates at a constant speed of 120 rpm. The magnitude of Coriolis component of aceelera tion of link 1 is
(a)302 m/s²
(b)604 m/s²
(c)906 m/s²
(d) 1208 m/s²
26. The figure below shows a planar mechanism with single degree of freedom.

The instant center 24 for the given configuration is located at a position ?
(a) L
(b) M
(c) N
(d)Infinity
27.A uniform stiff rod of length 200 mm and having a weight of 300 N is pivoted at one end and connected to a spring at the other end.

For keeping the rod vertical in a stable position the minimum value of spring constant K needed is ?
(a) 300 N/m
(b) 400 N/m
(c) 500 N/m
(d) 1000 N/m
28. In a bolted joint two members are connected with an axial tightening force of 2200 N.

If the bolt used has metric threads of 4 mm pitch, the torque required for achieving the tightening force is?
(a)0.7Nm
(b)1.0 Nm
(c)1.4 Nm
(d) 2.8 Nm
Answers:

1	a
2	a
3	d
4	c
5	a
6	c
7	b
8	a
9	c
10	a
11	b
12	b
13	d
14	c
15	c
16	a
17	d
18	a
19	a
20	d
21	b
22	c
23	b
24	c
25	a
26	c
27	c
28	c