Explore topic-wise InterviewSolutions in Current Affairs.

This section includes 7 InterviewSolutions, each offering curated multiple-choice questions to sharpen your Current Affairs knowledge and support exam preparation. Choose a topic below to get started.

1.

Give the importance of periodic sine and cosine functions.

Answer»

Solution :Any periodic FUNCTION can be expressed as a superposition of SINE and cosine function of DIFFERENT time PERIODS with suitable coefficients.
Discussion
2.

How does the time period of a simple pendulum depend on the length of the pendulum ?

Answer»

Solution :The time period of SIMPLE pendulum is DIRECTLY proportional to the square root of its LENGTH.
Discussion
3.

The rise of liquid into capillary tube is h_(1).If the apparatus is taken in a lift moving up with acceleration, the height is h_(2), then

Answer»

`h_(1)=h_(2)`
`h_(1)lth_(2)`
`h_(1)gth_(2)`
`h_(2)=0`

ANSWER :C
Discussion
4.

A mass is whirled in a circular path with a constant angular velocity and its angular momentum is L. If the length of string is now halved keeping the angular velocity same, the new angular momentum is

Answer»

L/4
L/2
L
2L

Answer :A
Discussion
5.

A thin wire of mass .m. and length .L. is bent in the form of a ring. The M.I. of the ring about a tangential axis parallel to any of its diameters is

Answer»

`(mL^(2))/(2pi^(2))`
`(3ML^(2))/(8pi^(2))`
`(2ML^(2))/(5pi^(2))`
`(mL^(2))/(6PI^(2))`

ANSWER :B
Discussion
6.

One end of a spring of natural h and spring constant k is fixed at the ground and the other is fitted with a smooth ring a mass m which is allowed to slide, on a horizontal rod fixed at a height h as shown in figure. Initially the spring makes an angle of37^(@) with the vertical when the system is released from rest. Find the speed of the ring when the spring becomes vertical? [cos 37^(@)=4//5]

Answer»

`hsqrt(k/m)`
`h/2sqrt(k/m)`
`hsqrt((2K)/m)`
`h/4sqrt(k/m)`

ANSWER :D
Discussion
7.

The equations of two waves acting in perpendicular direction are given as x = a cos (omega t + delta) " and " y = a cos (omega t + alpha) " where " delta = alpha + pi//2 the resultant wave represents

Answer»

a parabola
a CIRCLE
an ellipse ·
a STRAIGHT LINE

Solution :a straight line
Discussion
8.

Lami's theorem is applicable only when the system of forces are in

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same plane
different plane
EQUILIBRIUM
NONE of the above

Solution :equilibrium
Discussion
9.

If the velocity of a rotating body of mass 50 kg is given by bar(V)=3bar(i)+4bar(j)+5bar(k) and radius vector bar(r )=2bar(i)+3bar(j)+4bar(k), then its angular momentum is.

Answer»

`50bari+50barj+50bark`
`50bari+100barj+50bark`
`50bari+50barj+100bark`
`-50bari+100barj-50bark`

ANSWER :D
Discussion
10.

A metre stick is balanced on a knife edge at its centre. When two coins, each of mass 5 gare put one on top of the other at the 12.0 cm mark, the stick is found to be balanced at 45.0 cm, what is the mass of the meter stick?

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SOLUTION :`m=66.0 GM`
Discussion
11.

A gun fires a bullet at a speed of 140ms^(-1). If the bullet is to hit a target at the same level as the gun and at 1 km distance, the angle of projection may be

Answer»

`60^(@)` or `30^(@)`
`40^(@)` or `50^(@)`
`15^(@)` or `75^(@)`
`20^(@)` or `70^(@)`

Answer :C
Discussion
12.

Match Column-I with Column-II : {:("Column-I","Column-II"),("(1) Kepler's "1^(st)" law","(a) Law of time period"),("(2) Kepler's "2^(nd)" law","(b) Law of orbit"),("(3) Kepler's "3^(rd)" law","(c) Law of area"):}

Answer»


ANSWER :(1-b), (2-c), (3-a)
Discussion
13.

The upper half of an in clin ed plane of inclination 30^(@) is perfectly smooth, while the lower half is rough. A block starts from rest from the top of the plane and if it comes back to rest at the bottom, what is the co-efficient of kinetic friction between the surface of block and the rough surface of the inclined plane ?

Answer»

2
`2sqrt(3)`
`(2)/SQRT(3)`
`sqrt(3)`

SOLUTION :ACCORDING to Textual ExerciseSection - Bsameas SUM No.9
Discussion
14.

The time period of simple pendulum is T. When the length increases by 10 cm , its peirod is T_(1). When the length is decreased by 10 cm, its period is T_(2). Then the relation between T, T_(1) and T_(2) is

Answer»

`2/(T^(2))=1/(T_(1)^(2))+1/(T_(2)^(2))`
`2/(T^(2))=1/(T_(1)^(2))-1/(T_(2)^(2))`
`2T^(2)=T_(1)^(2)+T_(2)^(2)`
`2T^(2)=T_(1)^(2)-T_(2)^(2)`

ANSWER :C
Discussion
15.

The Sun is a hot plasma (ionized matter) with its inner core at a temperature exceeding 10^(7)Kg, and its outer surface at a temperature of about 6000K. At these high temperatures , no substance remains in a solid or liquid phase. In what range do you expect the mass density of the Sun to be, in the range of densities of solids and liquids or gases ? Check if your guess is correct from the following data: mass of the Sun =2.0xx10^(30)Kg, radius of the Sun =7.0xx10^(8)m.

Answer»

Solution :`1.4xx10^(3) kg m^(-3)`, the MASS density of the SUN is in the range of densities of liquids/ solids and not gases. This high density ARISES due to inward gravitational attraction `1.429xx10^(5)` km
Discussion
16.

What is the nature of the thermal change in air, when a sound wave propagates through it ?

Answer»

Solution :When the SOUND WAVE TRAVEL through air adiabatic changes TAKE PLACE in the medium.
Discussion
17.

|AxxB|^(2)+(A.B)^(2) is equal to

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`A^(2)+B^(2)`
`(A^(2)B^(2)`
`(2A^(2)B^(2)`
zero

Answer :B
Discussion
18.

Which quantity is conserved for a satellite revolving around the earth in a fixed orbit?

Answer»

<P>

Solution : In motion of satellite, angular momentum is CONSERVED.
L = mvr = constant
In CASE of circular orbit, RADIUS r is constant.
` therefore ` mv = constant .
` therefore ` Linear momentum (p) is also conserved.
Discussion
19.

(A): Isobaric bulk modulus is zero.(R) : Isobaric process is a process in which pressure is constant

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Both (A) and (R) are true and (R) is the CORRECT EXPLANATION of (A)
Both (A) and (R) are true and (R) is not the correct explanation of (A)
(A) is true but (R) is false
Both (A) and (R) are false

Answer :A
Discussion
20.

The root mean square speed of molecules of ideal gases at the same temperature are

Answer»

The same
Inversely PROPORTIONAL to the SQUARE ROOT of the MOLECULAR weight
Directly proportional to the molecular weight
Inversely proportional to the molecular weight.

Answer :B
Discussion
21.

The period of 0scillation of a simple pendulum is recorded as 2.63s, 2.56s,2.42s ,2.71s and 2.80s respectively. The average absolute error is ..............

Answer»

SOLUTION :Mean ABSOLUTE ERROR = `(sum|Detla T_i|)/(n)`
` Delta T_m = (0.01+ 0.06 + 0.20 + 0.90 + 0.18 )/(5)`
`Delta T_m = (0.54)/(5) = 0.108 s= 0.11 s ` (Rounded of to 2ND DECIMAL place )
Discussion
22.

Passage - I: The graph between two temperature scales A and B is as shown in fig. Between upper fixed and lower fixed points there are 150 equal divisions on scale A and 100 on scale B. The relation between two scales A and B is given by

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`(T_A - 180)/( 100)= (T_B)/( 150) `
`(T_A - 30)/( 150) = (T_B)/( 100) `
`(T_B - 180)/( 150)= (T_A)/( 100) `
`(T_B - 40)/( 100) = (T_A)/( 180)`

ANSWER :B
Discussion
23.

The particles of mud fly off tangentially from the wheel of a moving vehicle . Explain.

Answer»

SOLUTION :When the particles of mud fly off from the WHEEL they continue to move with uniform velocity ALONG a STRAIGHT line which is the tangent to the wheel . This is due to inertia of motion .
Discussion
24.

Assertion: Even when orbit of a satellite is elliptical , its plane of rotation passes through the centre of earth. Reason: According to law of conservation of angular momentum plane of rotation of satellite alwaysremain same.

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Both ASSERTION and Reason are true and Reason is the CORRECT EXPLANATION of Assertion
Both Assertion and Reason are true and Reason is not the correct explanation of Assertion
Assertion is true and Reason is FALSE
Assertion is false and Reason is true

Answer :A
Discussion
25.

Passage - I: The graph between two temperature scales A and B is as shown in fig. Between upper fixed and lower fixed points there are 150 equal divisions on scale A and 100 on scale B. Lower fixed point on scale B and scale A.

Answer»

`30^(@).0^(@)`
`0^(@),30^(@)`
`30^(@),27^(@)`
`27^(@),30^(@)`

ANSWER :A
Discussion
26.

A uniform disc of diameter R/2 is put over another uniform disc of radius R of same thickness and density. The peripheries of the two discs touch each other. Locate the centre of mass of the system.

Answer»


ANSWER :`(3R)/68` from the centre of larger DISC TOWARDS the centre of the smaller disc
Discussion
27.

The blades of a windmill sweep out a circle of area A. If the wind flows at a velocity v perpendicular to the circle, what is the mass of the air passing through it in time t?

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SOLUTION :`m= PAVT`
Discussion
28.

A research satellite of mass 200 kg circles the earth in an orbit of average radius 3R/2, where R is the radius of the earth. Assuming the gravitational pull on the mass of 1kg on the earth.s surface to be 10 N, the pull on the satellite will be

Answer»

1212 N
889 N
1280 N
960 N

ANSWER :B
Discussion
29.

Two identical disc are placed one over the other and both are rotating about a common axis through their centre and normal to their frame with angular velocity omega. If the upper disc is suddenly removed, angular velocity of the other disc would be

Answer»

`OMEGA`
`omega//2`
`2OMEGA`
`4OMEGA`

ANSWER :C
Discussion
30.

A gas is compressed isothermally to half its initial volume. The same gas is compressed seperately through an adiabatic process until its volume is again reduced to half. Then _____

Answer»

Compressing the GAS through adiabatic PROCESS will require more work to be done.
Compressing the gas through isothermally or adiabatically will require more work to be done.
Which of the case (WHETHER compression through isothermal or through adiabatic process) requires more work will depend upon the ATOMICITY of the gas.
Compressing the gas isothermally will require more work to be done.

Solution :
Discussion
31.

Assirtion Degree of freedom of a monjoatomic gas is always three, whether we concider vubrationaol effects or not. Reason At all temperatures (low or high), vibrational kinetic energy of an ideal gas is zero

Answer»

If both ASSERTION and Reason are correct and Reason is the correct EXPLANATION of Assertion.
If both Assertion and Reason are correct but Reason is not the correct explation os Assertion.
If Assertionis TRUE bur Reason is false.
If Assertion is false but Reason is true.

Solution :In ideal gases, there is no inter-partical interaction. If the gas is monoatomic so no VIBRATIONAL energy is there. `therefore` Only the kinetic energy contribute to the internal energy.
Discussion
32.

The two thight bones (femurs ) each of cross- sectional area 12cm^(2) support the upper part of a human body of mass 40 kg . Estimate the average pressure sustained by the femurs. (g=10ms^(-2)).

Answer»

SOLUTION :AVERAGE pressure `=1.7xx10^(5)Nm^(-2)`
Discussion
33.

In design of a compensated pendulum, a light metal rod of length L_(0) = 1.0 m is attached to a glass tube filled with mercury. Neglecting the mass of the glass tube as well, calculate the height of mercury column in the glass tube so that centre of mass of this system does not rise or fall with temperature Given : lambda_)Hg)=1.82xx10^(-4)K^(-1),alpha_("glass')=9xx10^(-6),alpha_("metal")=1.2xx10^(-5)K^(-1)

Answer»


ANSWER :`(2L_(0)alpha_("METAL"))/(gamma_(m)-2alpha_(g)) =0.146 m `
Discussion
34.

A disc of mass.m. and radius R has a concentric hole of radius .r.. Its M.I. about an axis through centre and normal to its plane is

Answer»

`m/2(R-r)^(2)`
`m/2(R^(2)-r^(2))`
`m/2(R+r)^(2)`
`m/2(R^(2) + r^(2))`

ANSWER :D
Discussion
35.

A body is in motion and it is stopped by applying retarding force. Initial speed magnitude of force applied are as given below{:(,"Speed","Force"),((1),V,F),((2),2V,F//2),((3),V//2,2F):}If S_(1), S_(2), S_(3) are the distances travelled before coming to rest, those can be arranged in ascending order as given below

Answer»

`S_(1),S_(2),S_(3)`
`S_(3),S_(2),S_(1)`
`S_(2),S_(1),S_(3)`
`S_(3),S_(1),S_(2)`

ANSWER :D
Discussion
36.

An insect of mass m=1 gm moves with a velocity v= hat(i) - 2hat(j) + hat(k) m//s. Find its angular momentum vec(L) about the origin O when the insect passes through the point P(-1, 1,2) m. Use vec(L) = vec(r ) xx m vec(v)

Answer»

`(5 HAT(i) + 3hat(J)+ hat(k)) 10^(-3)`
`(3 hat(j) + hat(k))`
`(5 hat(i) - 3hat(j))`
null vector

Answer :A
Discussion
37.

Three blocks A, B and C of m asses 4kg, 2kg and lkg respectively are in con tact on a frictionless surface, as show n. If a force of 14 N is applied o n th e 4kg b lo ck , th e n th e c o n ta c t fo rce betw een A and B is

Answer»

2n
6N
8n
18n

SOLUTION :Acceleration of system`=(f_(net))/( M_(total )) `
`= (14)/(4+2+1) = 2 m//s^(2)`

thecontactforcebetween4 KG&2kg blockwillmove 2kg &1kgblockwithsameacceleration
so`F_(CONTACT ) = (2+ 1 )a= 3 (2) = 6N`
Discussion
38.

Two pipes are submerged in sea water , arranged as shown in figure . Pipe (A) with length L_(A) = 1.5 m and one open end , contains a small source that sets up the standing wave with the second lowest resonant frequency of that pipe . Sound from pipe A sets up resonance in pipe B , which has both ends open . The resonance is at the second lowest resonant frequency of pipe B. The length of the pipe B is :

Answer»

` 1 m`
`1.5 m`
` 2 m`
`3 m`

Solution :For pipe `A`, second RESONANT frequency is third harmonic thus ` f= ( 3V)/( 4 L_(A))`
For pipe `B` , second resonant frequency is second harmonic thus `f = ( 2V)/( 2 L_(B))`
Equating , `(3 V)/( 4L_(A)) = ( 2 V)/( 2L_(B))`
`rArr L_(B) = (4)/(3) L_(A) = (4)/(3) . (1.5) = 2 m`
Discussion
39.

Draw position time graph of two objects, A & B moving along a straight line, when their relative velocity is zero.

Answer»

SOLUTION :
Discussion
40.

A wooden object the same in water in a beaker. The object is near a side of the beaker as shown in figure. Let P_(1)P_(2)P_(3) be the pressure at the three points a,B and C of the bottom as shown in the figure.

Answer»

`P_(1)=P_(2)=P_(3)`
`P_(1)ltP_(2)ltP_(3)`
`P_(1)gtP_(2)gtP_(3)`
`P_(2)=P_(3)!=P_(1)`

Answer :A
Discussion
41.

The period of Moon's rotation around the Earth is nearly 29 days.If Moon's mass were 2 fold its present value and all other things remained unchanged the period of Moon's rotation would be nearly ............ days.

Answer»

`29sqrt(2)`
`29/(sqrt(2))`
`29xx2`
29

Solution :Time PERIOD does not DEPENDS upon the mass of SATELLITE .
Discussion
42.

The radius vector and linear momentum are respectively given by vectors 2hati + hatj + hatk and 2hati - 3hatj + 3hatk Then the angular momentum is

Answer»

`2hati - 4hatk`
`4 hati- 8 hatk`
`2hati - 4 hatj +2hatk`
`4 hati - 8 hatj`

Solution :Given radius vector , `vecr = 2 hati + hatj + hatk`
Linear MOMENTUM `, VECP = 2 hati - 3hatj + hatk`
As angular momentum , `VECL = vecr xx vecp = |{:(hati , hatj , hatk) , (2 , 1 , 1) , (2 , -3 , 1):}|`
`= hati (1 - (-3)) - hatj (2 - 2) + hatk (-6 - 2) = 4 hati - 8 hatk`
Discussion
43.

A wheel in uniform motion about an axis passing through its centre and perpendicular to its plane is considered to be in mechanical (translational plus rotational) equilibrium becaues no net external force or torque is required to sustain its motion. However, the particles that constitute the wheel do experience a centripetal the acceleration directed towards the centre. How do you reconcile this fact with the wheel being in equilibrium? How would you set a half wheel into uniform motion about an axis passing through the centre of mass of the wheel and perpendicular to its plane? Will you require external forces to sustain the motion?

Answer»

Solution :Wheel is a rigid body. The particles of the wheel experience centipetal ACCELERATION towards the CENTRE. This acceleration increases DUE to internal elastic forces, which cancel out in pairs.
In a half wheel, the distribution of mass about its centre of mass (through which axis of rotation PASSES) is not symmetrical. Therefore, the direction of angular MOMENTUM of the wheel does not coincide with the direction of its angular velocity. Hence, an external torque is required to sustain the motion of the half wheel.
Discussion
44.

Defineheatengine .

Answer»

Solution :HEAT engine is a device which takes heat as INPUT and converts this heat in to WORK by UNDERGOING a cyclic process.
Discussion
45.

A capillary tube is attached horizontally at a constant head arrangement. If the radius of the capillary tube is increased by 1.5%, the rate of flow of liquid changes by about

Answer»

`-4%`
`+4%`
`-6%`
`+6%`

ANSWER :D
Discussion
46.

A vertical force Facts on the cross-seaction of a cylinder body of radius .r. and length L. If Y is young.s modulus and sigma = possoing ratio, find the change in volume of the body?

Answer»


ANSWER :`(FL(1-2sigma))/(Y)`
Discussion
47.

Choose the correct optionsThe turning effect of the applied force does NOT depend upon

Answer»

MAGNITUDE of the force
direction of the force
moment ARM of the force
MATERIAL and its distance from the AXIS

Answer :material and its distance from axis of ROTATION
Discussion
48.

The magnitude of the electric field of an infinite plane sheet of charge (as given by E=(sigma)/(in_0) is independent of the disance from the sheet.E prop (1)/(r^2) is not followed here. Can you guess why?

Answer»

SOLUTION :This is because the ENTIRE CHARGE is on the INFINITE PLANE and does not depend on the distanced r from the plane.
Discussion
49.

If L=20.04m+-0.01m, B=2.52m+-0.02m.What are the values of (LxxB) and (L-:B)?

Answer»

Solution :Given ERRORS are absolute errors, while the rule says that percentage errors are to be added.(You can USE relative or fractional errors also in place of percentage errors, brt you will find it LESS confusing while DEALING with percentage errors). Hence , the first step will be to convert the given absolute errors in percentage errors.
`:. L =20.04m+-(0.01)/(20.04)xx100%=20.04m+-0.049%`
`B=2.52m+-(0.02)/(2.52)xx100%=2.52m+-0.79%`
`:. LxxB =(20.04xx2.52)m^(2)+-(0.049+0.79)%=50.50m^(2)+-0.8395`
This is the result . However , since the data given in the question was in terms of absolute errors. so we should GIVE our result also in absolut errors
`LxxB=50.50m^(2)+-(0.839)/(100)xx50.50m^(2)=50.50m^(2)+-0.423m^(2)=50.50m^(2)+-0.42m^(2)`
Similarly, `L/B=(20.40cancel(m))/(2.52cancel(m))+-(0.049+0.79)%=7.95+-0.839%=7.95+-(0.839)/(100)xx7.95=7.95+-0.066.`
The result should be rounded to which place of decimal is explained later in this chapter.
Discussion
50.

To what height should a cylindervessel be filled with a homogeneous liquid to make the force with which the liquied presses fo the siede of the vessel equal to the forece exerted by the liquid on the bottom of the vessel ?

Answer»

<P>

Solution :let h be the height of liquid column of density `rho` in the cylindrical vessel of radius r. The froce acting on the bottom of vessel=weight of liquid filled in cylinder ` = mg = (pi r^2 h rho)g` …. (i) The area of walls incontact with liquid` = 2pi rho` Average pressure of liquid on walls is `P = ("pressure at bottom "+ "pressrue at top of liquid column")/(2)`
` = (rho gh _ 0)/(2) = (rho gh)/(2)`
Force on the walls of vessel `= (rho g h)/(2) xx 2pi r h = pi rho grh^2` ..... (ii)
As per question the forces (i) and (ii) are EQUAL so, `pi r^2 h rho g = pi rho g rh^2` or `h =r` it MEANS height of liquid coluum in vessel should be equal to its radius.
Discussion