# 410+ Engineering Physics Solved MCQs

88
44.3k
1.

## The property by which a body returns to its original shape after removal of the force is called

A. plasticity
B. elasticity
C. ductility
D. malleability
Explanation: when an external force acts on a body, the body tends to undergo some deformation. if the external force is removed and the body comes back to its original shape and size, the body is known as elastic body and this property is called elasticity.
2.

## The property of a material by which it can be beaten or rolled into thin plates is called

A. malleability
B. plasticity
C. ductility
D. elasticity
Explanation: a material can be beaten into thin plates by its property of malleability.
3.

## Which law is also called as the elasticity law?

A. bernoulli’s law
B. stress law
C. hooke’s law
D. poisson’s law
Explanation: the hooke”s law is valid under the elastic limit of a body. it itself states that stress is proportional to the strain within the elastic limit.
4.

## The materials which have the same elastic properties in all directions are called

A. isotropic
B. brittle
C. homogeneous
D. hard
Explanation: same elastic properties in all direction is called the homogenity of a material.
5.

## A member which does not regain its original shape after removal of the load producing deformation is said

A. plastic
B. elastic
C. rigid
D. none of the mentioned
Explanation: a plastic material does not
6.

## The body will regain it is previous shape and size only when the deformation caused by the external forces, is within a certain limit. What is that limit?

A. plastic limit
B. elastic limit
C. deformation limit
D. none of the mentioned
Explanation: the body only regain its previous shape and size only upto its elastic limit.
7.

## The materials which have the same elastic properties in all directions are called

A. isotropic
B. brittle
C. homogenous
D. hard
Explanation: isotropic materials have the same elastic properties in all directions.
8.

## As the elastic limit reaches, tensile strain

A. increases more rapidly
B. decreases more rapidly
C. increases in proportion to the stress
D. decreases in proportion to the stress
Explanation: on reaching the tensile stress to the elastic limit after the proportionality limit, the stress is no longer proportional to the strain. then the value of strain rapidly increases.
9.

## What kind of elastic materials are derived from a strain energy density function?

A. cauchy elastic materials
B. hypo elastic materials
C. hyper elastic materials
D. none of the mentioned
Explanation: the hyper elastic materials are derived from a strain energy density function. a model is hyper elastic if and only if it is possible to express the cauchy stress tensor as a function of the deformation gradient.
10.

## What the number that measures an object’s resistance to being deformed elastically when stress is applied to it?

A. elastic modulus
B. plastic modulus
C. poisson’s ratio
D. stress modulus
Explanation: the elastic modulus is the ratio of stress to strain.
11.

## The slope of the stress-strain curve in the elastic deformation region is

A. elastic modulus
B. plastic modulus
C. poisson’s ratio
D. none of the mentioned
Explanation: the elastic modulus is the ratio of stress and strain. so on the stress strain curve, it is the slope.
12.

## What is the stress-strain curve?

A. it is the percentage of stress and stain
B. it is the relationship between stress and strain
C. it is the difference between stress and strain
D. none of the mentioned
Answer» B. it is the relationship between stress and strain
Explanation: the relationship between stress
13.

## Which point on the stress strain curve occurs after the proportionality limit?

A. upper yield point
B. lower yield point
C. elastic limit
D. ultimate point
Explanation: the curve will be stress strain proportional upto the proportionality limit. after these, the elastic limit will occur.
14.

## Which point on the stress strain curve occurs after the lower yield point?

A. yield plateau
B. upper yield point
C. ultimate point
D. none of the mentioned
Explanation: the points on the curve comes in the given order,
15.

## Which point on the stress strain curve occurs after yield plateau?

A. lower yield point
B. upper yield point
C. ultimate point
D. breaking point
Explanation: after the yield plateau the curve will go up to its maximum limit of stress which is its ultimate point.
16.

## Which point on the stress strain curve occurs after the ultimate point?

A. last point
B. breaking point
C. elastic limit
D. material limit
Explanation: after the ultimate point the value of stress will reduce on increasing of strain and ultimately the material will break.
17.

## Elastic limit is the point

A. up to which stress is proportional to strain
C. up to which if the load is removed, original volume and shapes are regained
D. none of the mentioned
Answer» C. up to which if the load is removed, original volume and shapes are regained
Explanation: the elastic limit is that limit up to which any material behaves like an elastic material.
18.

## What is the point P shown on the stress strain curve?

A. upper yield point
B. yield plateau
C. elastic limit
D. ultimate point
Explanation: it is the point showing the maximum stress to which the material can be subjected in a simple tensile stress.
19.

## What is the point P shown in the stress- strain curve?

A. lower yield point
B. elastic limit
C. proportionality limit
D. breaking point
Explanation: the breaking point is the point where the material breaks. the breaking point will be the last point on the stress strain curve.
20.

## What is the point shown in the stress strain curve?

A. elastic limit
B. lower yield point
C. yield plateau
D. lower strain point
Explanation: it is the lower yield point at which the curve levels off and plastic deformation begins.
21.

## Where is the necking region?

A. the area between lower yield point and upper yield point
B. the area between the plastic limit and elastic limit
C. the area between the ultimate point and initial point
D. the area between the ultimate point and rupture
Answer» D. the area between the ultimate point and rupture
Explanation: necking is a tensile strain deformation which is cased in after the ultimate amount of stress occurs in the material.
22.

## What is the elastic modulus of steel?

A. 69-79 gpa
B. 41-45 gpa
C. 190-217 gpa
D. 330-360 gpa
Explanation: steel has an elastic modulus of 190-217 gpa. it has e higher than aluminum and magnesium alloys. but lower than tungsten and molybdenum alloys.
23.

## What is the elastic modulus of titanium alloys?

A. 150-170 gpa
B. 180-214 gpa
C. 80-130 gpa
D. 41-45 gpa
Explanation: titanium alloys have the elastic modulus in the range of 80 to 130 gpa. it is greater than aluminum and magnesium alloys but lesser than steel.
24.

## What is the order of elastic modulus for Nickel alloys, Lead alloys, Molybdenum alloys, alumina?

A. pb < mo < ni < al2o3
B. ni < pb < mo < al2o3
C. pb < ni < mo < al2o3
D. pb < ni < al2o3 < mo
Answer» C. pb < ni < mo < al2o3
Explanation: lowest elastic modulus is of lead and its alloys of 14-18 gpa. ni and mo alloys have elastic modulus of 180-214 and 330-360 gpa respectively. al2o3 has highest e among the four of 415 gpa.
25.

## What property enhances with a decrease in E?

A. flexibility
B. stiffness
C. hardness
D. uts
Explanation: the lower the elastic modulus of material, the more flexible it is. bending of material becomes easier. on the other hand, stiffness decreases.
26.

## What is the unit of elastic modulus?

A. mohs
B. gpa
C. kg
D. n
Explanation: elastic modulus is expressed in gpa. mohs is the unit used for hardness.
27.

## When applied stress is of shear type, the modulus of elasticity is known as

A. bulk modulus
B. modulus of resilience
C. shear modulus
D. stiffness
Explanation: when the type of stress applied is shear, e is known as shear modulus. it is also known as modulus of rigidity. stiffness is measured in terms of e.
28.

## Which of the following tensile property is dimensionless?

A. tensile stress
B. elastic modulus
C. true strain
D. toughness
Explanation: true strain is dimensionless property. tensile strength and elastic modulus are measured in mpa and gpa respectively.
29.

## What is a factor which controls the elastic modulus?

A. alloying
B. heat treatment
C. interatomic forces
D. cold working
Explanation: on a constant temperature and pressure, e only is function of two factors.
30.

## Stress should not exceed        when in service.

A. yield strength
B. tensile strength
C. fracture strength
D. toughness
Explanation: above yield strength, material starts to deform plastically. it causes a change in dimensions and properties of a material. so material should be used below it.
31.

## Stress should not exceed        when in mechanical working

A. yield strength
B. tensile strength
C. fracture strength
D. toughness
Explanation: mechanical working process consists of plastic deformation. so it is performed above yield strength. but it is limited below tensile strength so as to avoid fracture.
32.

## Ductility of material is its ability to flow plastically under compressive load.

A. true
B. false
Explanation: ductility is a tensile property. it is studied under tensile loading. it is the ability to plastic flow without rupture.
33.

## Work per unit volume of the material is a known modulus of toughness.

A. true
B. false
Explanation: toughness is measured by the amount of work per unit volume of the material under static loading. work per unit volume of material is called modulus of toughness.
34.

## Which of the following cannot be determined using a torsion test?

A. modulus of elasticity in shear
B. torsion yield strength
C. modulus of rupture
D. young’s modulus
Explanation: modulus of elasticity in shear, torsion yield strength and modulus of rupture can all be determined by performing torsion test on material.
35.

## What is the use of weight head in a torsion testing equipment?

A. holding the job only
B. holding the job and applying twisting moment
C. holding the job and measuring the twisting moment
D. it is not a part of torsion testing equipment
Answer» C. holding the job and measuring the twisting moment
Explanation: the main job of weight head is to hold the job and measure the twisting moment.while twisting head holds the other end of job and applies twisting moment.
36.

## Which of the following is used to measure how much the specimen is twisted?

A. micrometer
B. clinometer
C. troptometer
D. tropometer
Explanation: troptometer is an instrument which is used for measuring the angular distortion of the material. mocrometer and vernier callipers are used to measure length. tropometer measures amount of torsion for a bone.
37.

## Torsional stress multiplied with original cross sectional are is:

Explanation: torsional stress is given by the ratio of maximum twisting load and original are of cross section of the material. therefore, torsional stress multiplied with original cross sectional gives us maximum twisting load.
38.

## Plastic deformation can only occur in case of torsional force.

A. true
B. false
C. topic 1.4 torsional stress and deformations
Explanation: the above given statement is false as plastic deformation can occur in case of tensile, compressive and torsional load after a point. after this point, the body cannot recover its original shape.
39.

## What is the unit of polar moment of inertia?

A. m2
B. m5
C. m3
D. m4
Explanation: polar moment of inertia denoted by j, is given by integration of radius square with respect to small area of cross-
40.

## Torque is                      moment.

A. twisting
B. shear
C. bending
D. couple
Explanation: a cylindrical shaft is subjected to twisting moment or torque when a force is acting on the member tangentially at some radius in a plane of its cross section.
41.

## Shear stress on a solid bar and hollow bar is same for given dimension.

A. true
B. false
Explanation: shear stress for a hollow bar and a solid bar are different dimensions as the hollow bar has two dimensions, outer and inner radius because of which calculation is different than the solid bar which has only one diameter.
42.

## In which of the following the angle of twist increases fast for a small amount of torque?

A. cold working condition
B. hot working condition
C. warm working condition
D. the increase is the same for cold working, hot working and warm working
Explanation: when the torsion test is conducted in hot working, it is observed that for a slight change in torque on the given specimen the angle of twist increase fast as
43.

## Torsion is denoted by

A. r
B. q
C. t
D. n
Explanation: if the moment is applied in a plane perpendicular to the longitudinal axis of the beam (or) shaft it will be subjected to torsion. torsion is represented or denoted by t.
44.

## The SI units for torsion is

A. n m
B. n
C. n/m
D. m
Explanation: as torsion is a product of perpendicular force and radius, the units will be n m.
45.

## torsion is produced when twisting couple coincides with the axis of the shaft.

A. exact
B. pure
C. nominal
D. mild
Explanation: when a member is subjected to the equal and opposite twisting moment at its ends, then the member is said to be subjected under pure torsion. pure torsion is often produced when the axis of the twisting couple coincides with the axis of the shaft.
46.

## Which of the following is known as Re- entrant mouthpiece?

A. external mouthpiece
B. convergent mouthpiece
C. internal mouthpiece
D. cylindrical mouthpiece
Explanation: according to the position, mouthpieces are classified as an external mouthpiece and internal mouthpiece. if the tube projects inside the tank, it is called an internal mouthpiece or re-entrant or borda’s
47.

## What is the general value for coefficient of contraction?

A. 0.64
B. 0.67
C. 0.66
D. 0.7
Explanation: the ratio of the area of a jet at vena contracta to the area of orifice is known as the coefficient of contraction. the value of cc varies from 0.61 to 0.69 for different orifices. generally, for sharp edged orifice the value of cc may be taken as 0. 64.
48.

## The Cd value for internal mouthpiece running free is

A. 0.6
B. 0.5
C. 0.7
D. 0.8
Explanation: the cd value for internal mouthpiece running free is 0.5.
49.

## is the velocity with which water reaches the notch or before it flows over it.

A. velocity of contact
B. velocity of moment
C. velocity of approach
Explanation: the velocity of approach is defined as the velocity with which water reaches the notch or weir before it flows over it. this velocity of approach creates an additional head “ha” equal to va2 / 2g and effect head over the notch is increased to h+ha.
50.

## Which of the following is also known as V notch?

A. trapezoidal
B. stepped
C. triangular
D. sharp edged
Explanation: a triangular notch also called a v notch is of triangle shape with apex down. the expression of the discharge over triangular notch or weir is q = 8/15 cd (2g) 1/2 × h 5/2.
51.

## Calculate the discharge over rectangular Weir of 3 metres length under the head of 400mm.Use Francis formula.

A. 1.268 m3/s
B. 1.396 m3/s
C. 1.475 m3/s
D. 1.528 m3/s
Explanation: francis formula for discharge q = 1.84 lh3/2.
52.

## converts mechanical energy into hydraulic energy.

A. dynamo
B. pump
C. turbine
D. generator
Explanation: a pump is a mechanical device which converts the mechanical energy into hydraulic energy. the hydraulic energy is in the form of pressure energy. the pumps are generally used for lifting liquid from a lower level to a higher level.
53.

## Torsional sectional modulus is also known as

A. polar modulus
B. sectional modulus
C. torsion modulus
D. torsional rigidity
Explanation: the ratio of polar moment of inertia to radius of section is called polar modulus or torsional section modulus. its units are mm3 or m3 (in si).
54.

## is a measure of the strength of shaft in rotation.

A. torsional modulus
B. sectional modulus
C. polar modulus
D. torsional rigidity
Explanation: the polar modulus is a measure of the strength of shaft in rotation. as the value of polar modulus increases torsional strength increases.
55.

## What are the units of torsional rigidity?

A. nmm2
B. n/mm
C. n-mm
D. n
Explanation: the product of modulus of rigidity (c) and polar moment of inertia (j) is called torsional rigidity. torsional rigidity is a torque that produces a twist of one radian in a shaft of unit length.
56.

## The angle of twist can be written as

A. tl/j
B. cj/tl
C. tl/cj
D. t/j
Explanation: the angle of twist = tl/cj
57.

## The power transmitted by shaft SI system is given by

A. 2πnt/60
B. 3πnt/60
C. 2πnt/45
D. nt/60 w
Explanation: in si system, power (p) is measured in watts (w) ; p = 2πnt/60 where t = average torque in n.m
58.

## Area of catchment is measured in

A. mm3
B. km2
C. km
D. mm
Explanation: catchment area can be defined as the area which contributes the surplus water present over it to the stream or river. it is an area which is responsible for maintaining flow in natural water bodies. it is expressed in square kilometres.
59.

## catchment area is a sum of free catchment area and intercepted catchment area.

A. total
C. combined
D. overall
Explanation: combined catchment area is defined as the total catchment area which contributes the water in to stream or a tank. combined catchment area = free catchment area + intercepted catchment area.
60.

## has steep slopes and gives more run off.

A. intercepted catchment area
B. good catchment area
C. combined catchment area
D. average catchment area
Explanation: good catchment area consists of hills or rocky lands with steep slopes and little vegetation. it gives more run off.
61.

## Trend of rainfall can be studied from

A. rainfall graphs
B. rainfall records
C. rainfall curves
D. rainfall cumulatives
Explanation: rainfall records are useful for calculating run off over a basin. by using rainfall records estimate of design parameters of irrigation structures can be made. the maximum flow due to any storm can be calculated and predicted.
62.

## Runoff coefficient is denoted by

A. p
B. n
C. k
D. h
Explanation: the runoff coefficient can be defined as the ratio of runoff to rainfall.
63.

## is a graph showing variations of discharge with time.

A. rising limb graph
B. crest graph
C. hydraulic graph
D. gauge graph
Explanation: hydrograph is a graph showing variations of discharge with time at a particular point of the stream. the hydrograph shows the time distribution of total run off at a point of measurement.
64.

## Calculate the torque which a shaft of 300 mm diameter can safely transmit, if the shear stress is 48 N / mm2.

A. 356 knm
B. 254 knm
C. 332 knm
D. 564 knm
Explanation: given, the diameter of shaft d
65.

## What is the bending moment at end supports of a simply supported beam?

A. maximum
B. minimum
C. zero
D. uniform
Explanation: at the end supports, the moment (couple) developed is zero, because there is no distance to take the perpendicular acting load. as the distance is zero, the moment is obviously zero.
66.

## What is the maximum shear force, when a cantilever beam is loaded with udl throughout?

A. w×l
B. w
C. w/l
D. w+l
Explanation: in cantilever beams, the maximum shear force occurs at the fixed end. in the free end, there is zero shear force. as we need to convert the udl in to load, we multiply the length of the cantilever beam with udl acting upon. for maximum shear force to obtain we ought to multiply load and distance and it surely occurs at the fixed end (w×l).
67.

## What is the maximum bending moment for simply supported beam carrying a point load “W” kN at its centre?

A. w knm
B. w/m knm
C. w×l knm
D. w×l/4 knm
Explanation: we know that in simply supported beams the maximum bm occurs at the central span.
68.

## How do point loads and udl be represented in SFD?

A. simple lines and curved lines
B. curved lines and inclined lines
C. simple lines and inclined lines
D. cant represent any more
Answer» C. simple lines and inclined lines
Explanation: according to bis, the standard symbols used for sketching sfd are
69.

## curve is formed due to bending of over hanging beams.

A. elastic
B. plastic
C. flexural
D. axial
Explanation: the line to which the longitudinal axis of a beam bends or deflects or deviates under given load is known as elastic curve on deflection curve. elastic curve can also be known as elastic line or elastic axis.
70.

## The relation between slope and maximum bending moment is

A. directly proportion
B. inversely proportion
C. relative proportion
D. mutual incidence
Explanation: the relationship between slope and maximum bending moment is inversely proportional because, for example in simply supported beams slope is maximum at supports and zero at midspan of a
71.

## What is the SF at support B?

A. 5 kn
B. 3 kn
C. 2 kn
D. 0 kn
Explanation: total load = 2×2 = 4kn shear force at a = 4 kn ( same between a and c )
72.

## Where do the maximum BM occurs for the below diagram.

A. -54 knm
B. -92 knm
C. -105 knm
D. – 65 knm
Explanation: moment at b = 0 moment at c = – (10 × 3) × (3/2)
73.

## The ratio of maximum deflection of a beam to its                        is called stiffness of the beam.

B. slope
C. span
D. reaction at the support
Explanation: the stiffness of a beam is a measure of it’s resistance against deflection. the ratio of the maximum deflection of a beam to its span can be termed as stiffness of the beam.
74.

## Stiffness of the beam is inversely proportional to the            of the beam.

A. slope
B. support reaction
C. deflection
Explanation: stiffness of a beam is inversely proportional to the deflection. smaller the deflection in a beam due to given external load, greater is its stiffness.
75.

## The maximum          should not exceed the permissible limit to the span of the beam.

A. slope
B. deflection
D. l bending moment
Explanation: the maximum deflection of a loaded beam should not exceed the permissible limit in relation to the span of a beam. while designing the beam the designer
76.

## In cantilever beam the deflection occurs at

A. free end
C. through out
D. fixed end
Explanation: deflection can be defined as
77.

## The maximum deflection in cantilever beam of span “l”m and loading at free end is “W” kN.

A. wl3/2ei
B. wl3/3ei
C. wl3/4ei
D. wl2/2ei
Explanation: maximum deflection occurs at free end distance between centre of gravity of bending moment diagram and free end is x =
78.

## fluids are practical fluids

A. ideal
B. real
C. vortex
D. newtonian
Explanation: these fluids possess properties such as viscosity, surface tension. they are compressible in nature. the certain amount of resistance is always offered by the fluids, they also possess shear stress. they are also known as practical fluids.
79.

## The inverse of specific weight of a fluid is

A. specific gravity
B. specific volume
C. compressibility
D. viscosity
Explanation: specific volume is the volume of the fluid by unit weight it is the reciprocal of specific weight is denoted by “v”. si units are m3/n.
80.

## Specific gravity of water is

A. 0.8
B. 1
C. 1.2
D. 1.5
Explanation: the specific gravity is also called as relative density. it is dimensionless quantity and it has no units. the specific gravity of water is the ratio of specific weight of fluid to specific weight of water, as both
81.

## Compute the maximum deflection at free end of a cantilever beam subjected to udl for entire span of l metres.

A. wl4/8ei
B. wl4/4ei
C. wl3/8ei
D. wl2/6ei
Explanation: the slope at free end = a/ei = wl3/6ei
82.

## Which of the following is not an example of Malleability?

A. wrought iron
B. ornamental silver
C. torsteel
D. ornamental gold
Explanation: torsteel is an example of mechanical property ductility. the ductility is a property of a material by which material can be fractured into thin wires after undergoing a considerable deformation without any rupture.
83.

## Which of the following is not correct?

A. angles and t section are strong in bending
B. channels can be used only for light loads
C. i sections are most efficient and economical shapes
D. i section with cover plates are provided when large section modulus is required
Answer» A. angles and t section are strong in bending
Explanation: angles and t section are weak in bending. channels can be used only for light loads. i sections (rolled and built-up) are most efficient and economical shapes. i section with cover plates are provided when large section modulus is required. generally, islb or ismb are provided in such cases.
84.

## Local buckling can be prevented by

A. limiting width-thickness ratio
B. increasing width-thickness ratio
C. changing material
Explanation: local buckling of compression members of beam causes loss of integrity of
85.

## Which of the following is true?

A. in case of rolled section, less thickness of plate is adopted to prevent local buckling
B. for built-up section and cold formed section, longitudinal stiffeners are not provided to reduce width to smaller sizes
C. local buckling cannot be prevented by limiting width-thickness ratio
D. in case of rolled section, high thickness of plate is adopted to prevent local buckling
Answer» D. in case of rolled section, high thickness of plate is adopted to prevent local buckling
Explanation: in case of rolled section, higher thickness of plate is adopted to prevent local buckling. local buckling cannot be prevented by limiting width-thickness ratio. for built-up section and cold formed section, longitudinal stiffeners are provided to reduce width to smaller sizes.
86.

## Which of the following is not true?

A. only plastic section can be used in intermediate frames
B. slender sections are preferred in hot rolled structural steelwork
C. compact sections can be used in simply supported beams
D. semi-compact sections can be used for elastic designs
Answer» B. slender sections are preferred in hot rolled structural steelwork
Explanation: only plastic section can be used in intermediate frames which form collapse mechanism. compact sections can be used in simply supported beams which fail after reaching mp at one section. semi- compact sections can be used for elastic designs where section fails after reaching my at extreme fibres. slender sections are not preferred in hot rolled structural steelwork, but they are extensively used in cold formed members.
87.

## As per IS specification, the beam sections should be

A. not symmetrical about any principal axes
B. at least symmetrical about one of the principal axes
C. symmetrical about all principal axes
D. unsymmetrical about all principal axes
Explanation: the beam sections should be at least symmetrical about one of the principal axes as per is specification. angle and t- sections are inherently weak in bending while channels can only be used for light loads.
88.

## A beam is said to be of uniform strength, if

A. b.m. is same throughout the beam
B. shear stress is the same through the beam
C. deflection is the same throughout the beam
D. bending stress is the same at every section along its longitudinal axis
Answer» D. bending stress is the same at every section along its longitudinal axis
Explanation: beam is said to be uniform strength if at every section along its longitudinal axis, the bending stress is same.
89.

## Which stress comes when there is an eccentric load applied?

A. shear stress
B. bending stress
C. tensile stress
D. thermal stress
Explanation: when there is an eccentric load it means that the load is at some distance from the axis. this causes compression in one side and tension on the other. this causes bending stress.
90.

## What is the expression of the bending equation?

A. m/i = σ/y = e/r
B. m/r = σ/y = e/i
C. m/y = σ/r = e/i
D. m/i = σ/r = e/y
Answer» A. m/i = σ/y = e/r
Explanation: the bending equation is given by m/i = σ/y = e/r
91.

## On bending of a beam, which is the layer which is neither elongated nor shortened?

B. neutral axis
C. center of gravity
D. none of the mentioned
Explanation: when a beam is in bending the layer in the direction of bending will be in compression and the other will be in tension. one side of the neutral axis will be shortened and the other will be elongated.
92.

## Consider a 250mmx15mmx10mm steel bar which is free to expand is heated from 15C to 40C. what will be developed?

A. compressive stress
B. tensile stress
C. shear stress
D. no stress
Explanation: if we resist to expand then only stress will develop. here the bar is free to expand so there will be no stress.
93.

## The motion of the earth about its axis is periodic and simple harmonic.

A. true
B. false
Explanation: the earth takes 24 hours to complete its rotation about its axis, but the concept of to and fro motion is absent, and hence the rotation of the earth is periodic and not simple harmonic.
94.

## An object of mass 0.2kg executes simple harmonic motion along the x-axis with a frequency of (25/π)Hz. At the position x = 0.04, the object has kinetic energy of 0.5J and potential energy 0.4J. The amplitude of oscillation is?

A. 6cm
B. 4cm
C. 8cm
D. 2cm
Explanation: total energy, e=2π2 mv2 a2 0.5+0.4=2π2×0.2×(25/π)2 a2 a2=0.9/(0.4×252) a=3/(2×25)=3/50 m=6cm.
95.

## A spring of force constant 800N/m has an extension of 5cm. The work done in extending it from 5cm to 15cm is?

A. 8j
B. 16j
C. 24j
D. 32j
Explanation: at x1 = 5 cm, u1=1/2×k(x1)2=1/2×800×0.052=1j
96.

## A simple pendulum is attached to the roof of a lift. If the time period of oscillation, when the lift is stationary is T, then the frequency of oscillation when the lift falls freely, will be

A. zero
B. t
C. 1/t
D.
Explanation: in a freely falling lift, g=0
97.

## A lightly damped oscillator with a frequency v is set in motion by a harmonic driving force of frequency v’. When v’ is lesser than v, then the response of the oscillator is controlled by

A. spring constant
B. inertia of the mass
C. oscillator frequency
D. damping coefficient
Explanation: frequency of driving force is lesser than frequency v of a damped oscillator. the vibrations are nearly in phase
98.

## What is the time period of a pendulum hanged in a satellite? (T is the time period on earth)

A. zero
B. t
C. infinite
D. t/√6
Explanation: in a satellite, g= 0 t=2π√(l/g)=2π√(l/0)=∞.
99.

## Which of the following functions represents a simple harmonic oscillation?

A. sinωt-cosωt
B. sinωt+sin2ωt
C. sinωt-sin2ωt
D. sin2 ωt
Explanation: y=sinωt-cosωt dy/dt=ωcosωt+ωsinωt
100.

A. 16:1
B. 8:1
C. 4:1
D. 2:1