Mock paper for campus placement 4

Mock campus paper for mechanical 4

1) in impulse reaction turbines, the pressure drops,
a) in fixed nozzles
b) in moving nozzles
c) in fixed blades
d) in both fixed & moving blades
e) none of the above

2) why a single stage turbine is not used in practice?
a) It can’t generate much power
b) The control is not possible
c) Heat energy is not utilized fully
d) The rotational speed becomes very high requiring
large reduction gearing
e) Its efficiency is very low

3) The back pressure of condensing steam turbines can be
improved by
a) decreasing steam flow
b) decreasing steam temperature
c) injecting water in last stages
d) using debris filter to clean circulating water &
cleaning condenser tubes by rubber ball cleaning
equipment
e) reducing bled steam

4) the maximum blade efficiency of a single stage
impulse turbine having nozzle angle a , under ideal
conditions is
a) cos(a)/2
b) ((cos a)^2)/2
c) cos(2a)/2
d) cos 2a
e) (cos a)^2

5) The time constant of a thermocouple is
a) the time taken to attain the final temperature to be measured
b) the time taken to attain 50% of the value of initial temperature difference
c) the time taken to attain 63.2 of the value of initial temperature difference
d) determined by the time taken to reach 100oC from 0oC
e) none of the above

6) in the heat flow equation
Q=(ka(t1-t2))/x is known as
a) thermal resistance
b) thermal coefficient
c) temperature gradient
d) thermal conductivity
e) heat transfer

7) A non-dimensional number generally associated with natural convection heat transfer is
a) Grashoff number
b) Nusselt number
c) Weber number
d) Prandtl number
e) Reynold number

8) In counter flow heat exchangers
a) both the fluids at inlet (of heat exchanger where hot fluid enters) are in their coldest state
b) both the fluids at inlet are in their hottest state
c) both the fluids at exit in their coldest state
d) one fluid is in hottest state & other in coldest state at inlet
e) any combination is possible depending on design of heat exchanger.

9) A steam pipe is to be insulated by two insulating materials put over each other. For best results
a) better insulation should be put over pipe & better one over it
b) inferior insulation should be put over pipe & better one over it
c) both may be put in any order
d) whether to put inferior one over pipe or the better one would depend on steam temperature
e) unpredictable

10) the concept of overall coefficient of heat transfer is used in case of heat transfer by
a) conduction
b) convection
c) radiation
d) conduction & convection
e) convection & radiation

11) a bucket of water is hanging from a spring balance. An iron piece is suspended into water without touching sides of bucket from another support. The spring balance reading will
a) increase
b) decrease
c) remain same
d) increase/decrease depending on depth of immersion
e) unpredictable

12) the vapour pressure over the concave surface is
a) less than the vapour pressure over the planesurface
b) equal to tha vapour pressure over the plane surface
c) greater than the vapour pressure over the plane surface
d) zero
e) none of the above

13) which of the following instrument can be used for measuring speed of an aeroplane
a) Venturimeter
b) Orifice plate
c) Hot water anemometer
d) Rotameter
e) Pitot tube

14) Euller’s dimensionless number relates the following
a) inertial force & gravity
b) viscous force & inertial force
c) viscous force & buoyancy force
d) pressure force & inertial force
e) pressure force & viscous force

15) which of the manometer has highest sensitivity
a) U-tube with water
b) Inclined U-tube
c) U-tube with mercury
d) Micro-manometer with water
e) Displacement type

16) Centre of buoyancy is the
a) centroid of the volume of fluid vertically above the body
b) centre of the volume of floating body
c) centre of gravity of any submerged body
d) centroid of the displaced volume of fluid
e) none of the above

17) pitot tube is used for measurement of
a) pressure
b) flow
c) velocity
d) discharge
e) viscosity

18) principle of similitude forms the basis of
a) comparing two identical equipments
b) designing models so that the result can be converted to prototypes
c) comparing similarity between design & actual equipment
d) hydraulic designs
e) performing acceptance tests

19) separation of flow occurs when pressure gradient
a) tends to approach zero
b) becomes negative
c) changes abruptly
d) reduces to a value when vapour formation starts
e) does not follow continuity equation

20) weir in an opening
a) with closed perimeter & of regular form through which water flows
b) with prolonged sides having length of 2 to 3 diameters of opening in thick wall
c) with partially full flow
d) in hydraulic structure with regulation provision
e) none of the above

21) which is the false statement about true stress method
a) it does not exist
b) it is more sensitive to changes in both metallurgical & mechanical conditions
c) it gives a more accurate picture of the ductility
d) it can be correlated with stress-strain values in other tests like torsion, impact, combined stress tests etc.
e) it can be used for compression tests as well.

22) The buckling load for a given material depends on
a) slenderness ratio & area of cross-section
b) poisson’s ratio & modulus of elasticity
c) slenderness ratio & modulus of elasticity
d) senderness ratio, area of cross-section & modulus of elasticity
e) poisson’s ratio & slenderness ratio.

23) The materials which exhibit the same elastic properties in all directions are called
a) Homogeneous
b) Inelastic
c) Isotropic
d) Isentropic
e) Visco-elastic

24) The property of a material by virtue of which it can be beaten or rolled into plates is called
a) Malleability
b) Ductility
c) Plasticity
d) Elasticity
e) Rollability

25) In a tensile test, near the elastic limit zone, the
a) Tensile strain increases more quickly
b) Tensile strain decreases more quickly
c) Tensile strain increases in proportion to the stress
d) Tensile strain decreases in proportion to the stress
e) Tensile strain remains constant