Material Strength & Dairy
Machine Design
Compiled By: - Mr.
Mukul Verma
A Elastic limit
Q The ratio of linear stress to
linear strain is called
A Modulus of elasticity
Q The modulus of elasticity for mild
steel is approximately equal to
A 210kN/mm2
Q When the material is loaded within
elastic limit, then the stress is ......... to strain.
A Directly proportional
Q When a
hole of diameter ‘d' is punched in a metal of thickness `t', then
the force required to punch a hole is equal to
A πd.t.τu
Q The ratio of the ultimate stress
to the design stress is known as
A Factor of safety
Q The factor of safety for steel and
for steady load is
A 4
Q An aluminium member is designed
based on
A Yield stress
Q In a body, a thermal stress is one
which arises because of the existence of
A Temperature gradient
Q A localised compressive stress at
the area of contact between two members is known as
A Bearing stress
Q The Poisson’s ratio for steel
varies from
A 0.25 to 0.33
Q The stress in the bar when load is
applied suddenly is ............. as compared to the stress induced dueto
gradually applied load.
A Double
Q The energy stored in a body when
strained within elastic limit is known as
A Strain energy
Q The maximum energy that can be
stored in a body due to external loading upto the elastic limit is called
A Proof resilience
Q The strain energy stored in a
body, when suddenly loaded, is ...........the strain energy stored when same
load is applied gradually.
A 4 times
Q When a
machine member is subjected to torsion, the torsional shear stress set up in
the member is
A Maximum at both the centroidal axis and outer surface of
the member
Q The torsional shear
stress on any cross-section normal to the axis is ......... the distance from
the centre of the axis.
A Directly proportional to
Q The
neutral axis of a beam is subjected to
A Zero stress
Q At the
neutral axis of a beam,
A The layers do not undergo any strain
Q If d =
diameter of solid shaft and τ = permissible stress in shear for the shaft
material, then torsional strength of shaft is written as
A π/16 d3τ
Q Two shafts under
pure torsion are of identical length and identical weight and are made of same
material. The shaft A is solid and the shaft B is hollow. We can
say that
A Shaft B is better than shaft A
Q Rankine’s
theory is used for
A Brittle materials
Q Guest’s
theory is used for
A Ductile materials
Q At the
neutral axis of a beam, the shear stress is
A Maximum
Q The maximum shear
stress developed in a beam of rectangular section is ........the average shear
stress.
A 1.5 times
Q The
material suitable for the belts used in agricultural equipments is
A Rubber
Q The
power transmitted by means of a belt depends upon
A Velocity of the belt, tension under which the belt
is placed on the pulleys, arc of contact between the belt and the smaller
pulley
Q When
the speed of belt increases,
A The power transmitted will increase
Q In a
crossed belt drive, the shafts are arranged parallel and rotate in the
...........directions.
A Opposite
Q The
tension in the slack side of the belt is ............ the tension in the tight
side of the belt.
A Less than
Q In a flat belt
drive, the belt can be subjected to a maximum tension (T) and
centrifugal tension (TC). The condition for transmission of maximum
power is given by
A T = 3 TC
Q When a
belt drive is transmitting maximum power,
A Driving tension in tight side is twice the centrifugal
tension
Q All
stresses produced in a belt are
A Tensile stresses
Q The
centrifugal tension in the belt
A Has no effect on the power transmitted
Q Which
one of the following is a positive drive?
A Chain drive
Q The
chain drive transmits ............ power as compared to belt drive.
A More
Q In order to have
smooth operation, the minimum number of teeth on the smaller sprocket, for
moderate speeds, should be
A 21
Q The
speed of the sprocket reduces as the chain pitch .......... for a given number
of teeth.
A Increases
Q The
spring mostly used in gramophones is
A Flat spiral spring
Q Which
of the following spring is used in a mechanical wrist watch?
A Torsion spring
Q When a helical
compression spring is subjected to an axial compressive load, the stress
induced in the wire is
A Shear stress
Q When
helical compression spring is cut into halves, the stiffness of the resulting
spring will be
A Double
Q When two concentric
coil springs made of the same material, having same length
and compressed equally by an axial load, the load shared by
the two springs will be ............ to the square of the diameters of the
wires of the two springs.
A Directly proportional
Q A leaf
spring in automobiles is used
A To absorb shocks
Q In
leaf springs, the longest leaf is known as
A Master leaf
Q In a
full journal bearing, the angle of contact of the bearing with the journal is
A 360°
Q A sliding bearing
which can support steady loads without any relative motion between the journal
and the bearing is called
A Hydrostatic lubricated bearing
Q Teflon
is used for bearings because of
A Low coefficient of friction
Q In
thrust bearings, the load acts
A Along the axis of rotation
Q The
ball bearings are usually made from
A Chrome nickel steel
Q A
bearing is designated by the number 405. It means that a bearing is of
A Heavy series with bore of 25 mm
Q The
rolling contact bearings are known as
A Antifriction bearings
Q Which
material has the maximum ductility?
A Mild steel
Q Steel
containing upto 0.15% carbon is known as
A Dead mild steel
Q The
material commonly used for machine tool bodies is
A Cast Iron
Q The material commonly used for
crane hooks is
A Wrought Iron
Q Shock
resistance of steel is increased by adding
A Nickel and chromium
Q The
steel widely used for motor car crankshafts is
A Chrome steel
Q A
steel with 0.8 per cent carbon is known as
A Eutectoid steel
Q Ball
bearing are usually made from
A Medium carbon steel
Q The
process which improves the machinability of steels, but lower the hardness and
tensile strength is
A Spheroidising
Q The
metal suitable for bearings subjected to heavy loads is
A White metal
Q The
metal suitable for bearings subjected to light loads is
A Phosphor bronze
References:-
1.R.S. KHURMI & J.K. GUPTA
2. NDRI class notes
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