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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. |
A swinmmer is capable of swimming at 1.65ms^(-1) in still water . If he swims directly acrooss a 180m wide river with water flow at 0.85ms^(-1) how far down stream will be reach ? How long will it take to reach the other side? |
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Answer» |
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| 2. |
Obtain an expression for the aparent frequency of sound when the source of sound and the listener are movingtowards each other. |
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Answer» SOLUTION :For a source moving towards an observer ( assumed to be at REST), apparent frequency `f' = f_(0)((v)/( v-v_(s)))`  thereby wavelength `lambda == ( v- v_(s))/( f_(0))` For an observer moving towards the source, apparent frequency, `f' = (v+ v_(0))/( lambda ) `i.e, `f' = v_(0) ((v+v_(0))/(v-v_(s)))` Note `:` For `v_(0) LT lt v` and `v_(s)lt lt v`, `f' = f_(0) ((v+v_(0))/(v-v_(s)))` |
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| 3. |
A car moving at a constant speed of 36kmph moves north wards for 20 minutes then due to west with the same speed for 8(1)/(3) minutes.What is the average velocity of the car during this run in kmph |
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Answer» 27.5 |
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| 5. |
State whether the surface tension of a liquid increases or decreases due to an increases in temperature. |
| Answer» SOLUTION :DECREASES | |
| 6. |
The phase difference between two particies executing shm is pi//2. What does it mean? |
| Answer» Solution :When the displacement of ONE PARTICLE is ZERO the displacement of the other particle will be maximum | |
| 7. |
Whatere thedifferent types ofthermodynamicsystems ? |
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Answer» SOLUTION :(i) OPEN system can exchange both matter and energy with the environment. (II) Closed system exchange energy but not matter with the environment. (III) Isolated system can exchange neither energy nor matter with the environment. |
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| 8. |
What is a isobaric process ? |
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Answer» Solution :Isobaric process: This is a thermodynamic process that occurs at constant pressure. Even though pressure is constant in this process, temperature, volume and internal energy are not constant. From the ideal gas equation, we have `V=((muR)/(P))T"...(1)"` `"Here"(muR)/(P)=" constant"` In an isobaric process the temperature is directly proportional be volume. `V p rop T "(Iobaric process)...(2)"` This implies that for a isobaric process, the `V-T` graph is a straight line passing through the origin. If a gas goes from a STATE `(V_(i), T_(i))` to `(T_(f), T_(f))` at constant pressure, then the system satisfies the following equation `(T_(f))/(V_(f))=(T_(i))/(V_(i))"...(3)"` Examples for Isobaric process: (i) When the gas is heated and pushes the piston so that it exerts a force equivalent to atmospheric pressure plus the force due to gravity then this process is isobaric. (ii) Most of the cooking processes in our kitchen are isobaric processes. When the food is cooked in an open vessel, the pressure above the food is always at atmospheric pressure. The PV diagram for an isobaric process is a horizontal line parallel to volume axis. Figure (a) represents isobaric process where volume decreases figure (b) represents isobaric process where volume increases.  The work done in an isobaric process : Work done by the gas `W=int_(V_(i))^(V_(f))PdV"...(4)"` In an isobaric process, the pressure is constant, so P comes out of the integral, `W=P int_(V_(i))^(V_(f))PdV"...(4)"` `W=P[V_(f)-V_(i)]=P DeltaV"....(6)"` Where `DeltaV` denotes CHANGE in the volume. If `DeltaV` is negative, W is also negative. This implies that the work is done on the gas. If `DeltaV` is positive, W is also positive, implying that work is done by the gas. The equation (6) can also be rewritten using the ideal gas equation. From ideal gas equation `PV=muRT and V=(muRT)/(P)` Substituting this in equation (6) we get  `W=muRT_(f)(1-(T_(i))/(T_(f)))"...(7)"` In the PV diagram, area under the isobaric curve is equal to the work done in isobaric process. The SHADED area in the above diagram is equal to the work done by the gas. The first law of thermodynamics for isobaric process is given by `DeltaU=Q-PDeltaV"...(8)"` `W=PDeltaV, DeltaU=Q-muRT_(f)[1-(T_(i))/(T_(f))]` |
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| 9. |
For a surface molecule a) the net force on it is zero b) there is a net downward force c) the potential energy is less than that of a molecule inside d) the potential energy is more than that of a molecule inside |
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Answer» Both A & B are CORRECT |
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| 10. |
An object is attached to the bottom of a light vertical spring and set vibrating. The maximum speed of the object is 15 cm/sec and the period is 628 m sec. The amplitude of the motion in centimeter is |
| Answer» ANSWER :C | |
| 11. |
A force of 20 N acts on a body of mass 5kg at rest. What is the acceleration of the body? What is its velocity after 5 seconds if the same force acts? After 5 seconds if the force ceases to act how will the body move? |
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Answer» `4m//s^2` , 20 m/s, UNIFORM VELOCITY |
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| 12. |
In above question, what will be the speed of the particle on the ring which is at the same height as that of the centre? |
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Answer» v |
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| 13. |
The contact angle between a solid & a liquid is a property of |
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Answer» the MATERIAL of SOLID & liquid |
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| 14. |
A dise of radiu Rin reonat into a thin cylinder of same radius. Will their moments of inertin be equal. |
| Answer» Solution :In case of hollow cylinder, most of them is located at comparatively larger distance from the axis of rotation as COMPARED to the cine of same radio so, the hollow cylinder will have greater MOMENT of INERTIN than the DISC | |
| 15. |
Solve sqrt(6.5-6.32) by using significant figure. |
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Answer» Solution :`sqrt(6.5-6.32)=sqrt(0.18)` `=0.42464` Least SIGNIFICANT DIGIT is 1. Hence, near most VALUE will be 0.4. |
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| 16. |
What do you meanby inertia of rest |
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Answer» SOLUTION :WHENA stationerybusstartsto movethepassengersexperiencea suddenbackwardpush . EG: The inabilityof anobjectto changeits statefor restcalledinertiaof REST. |
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| 17. |
A man wishes to cross a river flowing with velocity u jumps at an angle theta with the river flow. Find out the net velocity of the man with respect to ground if he can swim with speed v. also find how for from the point directly opposite to th estarting point does the boat reach the opposite bank . In what direction does the boat actually move. If the width of the river is d. |
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Answer» Solution :Velocity of MAN `=V_(M)=sqrt(u^(2)+V^(2)+2V ucos theta)` `tanphi=(vsintheta)/(u+v costheta)` `(vsin theta)t=d RARR t=d/(v SIN theta)` `x=(u+v costheta )t=(u+v costheta)d/(v sin theta)` 
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| 18. |
A solid cylinder of mass 2 kg and radius 4 cm rotating about its axis at the rate of 3 rpm . The torque required to stop after 2pi revolutions is |
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Answer» `2 xx 10^(6) Nm` Initial ANGULAR speed `omega_(0) = 3 rpm = 3 xx (2pi)/(60)` rad/s = `(pi)/(10)` rad/s We know that , `omega_(2) = omega_(0)^(2) + 2 ALPHA theta` `implies 0 = ((pi)/(10))^(2) + 2 xx alpha xx 2pi xx 2pi implies alpha = (-1)/(800) "rad/s"^(2)` MOMENT of inertia of a solid cylinder , `I = (MR^(2))/(2) = (2 xx ((4)/(100))^(2))/(2) = (16)/(10^(4))` Torque `tau = I alpha = ((16)/(10^4)) xx (- (1)/(800)) = -2 xx 10^(-6) N m` |
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| 19. |
A sand bag of 10 kg mass is suspended by a 3 m long weightless string. A 0.2 kg mass bullet enters the bag with a velocity of 20 m s^(-1) and gets embedded into it. The loss in KE in the collision is |
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Answer» 40.2 J |
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| 20. |
A mass of 2kg oscillates on a spring with force constant 50 N/m. By what vactor does the frequency of oscillation decreases when a damping force with constant b = 12 is introduced ? |
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Answer» decreases by 10% |
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| 21. |
A vehicle moving on a straight road sounds a whistle of frequency 256Hz while nearing a hill with a velocity 10ms^(-1). The number of beats per second observed by a person travelling in the vehicle is (V=330ms^(-1)) |
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Answer» zero The no.of BEATS PRODUCED is `16` per second but no.of beats neard (OBSERVED) by OBSERVER .O. as maximum no.of beats heard is only `10` per second. |
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| 22. |
The angle between (bar(A) xx bar(B)) and (bar(B) xx bar(A)) is (in radiant) |
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Answer» `PI//2` |
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| 23. |
Identical springs of steel and copper are equally stretched. The spring on which more work is to be done is |
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Answer» steel |
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| 24. |
Radius of gyration of a disc of mass 5 kg about a transverse axis passing through its centre is 14.14 cm. Find its radius of gyration about its diameter and hence calculate its moment of inertia about its diameter |
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Answer» SOLUTION :Radius of gyration of a disc about a transverse axis PASSING through its centre `K = sqrt((I)/(M))=sqrt((MR^(2))/(2M))=(R )/(sqrt(2))=14.14 cm` `(therefore I =(MR^(2))/(2))` Radius of the disc, `R = 14.14xxsqrt(2)=20 cm` Radius of gyration of the disc about its diameter. `K= sqrt((I)/(M))=sqrt((MR^(2))/(4M))=(R )/(2)=(20)/(2)=10 cm` Moment of inertia about its diameter = `(MR^(2))/(4)=(5(0.2)^(2))/(4)=5.00xx10^(-2)KG m^(2)` |
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| 25. |
If the centre of mass of three particles of masses of 1kg, 2 kg, 3 kg is at(2, 2, 2), then where should a fourth particle of mass 4 kg be placed so that the combined centre of mass may be at (0, 0, 0). |
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Answer» Solution :`(x_(1),y_(1),z_(1)),(x_(2),y_(2),z_(2))` and `(x_(3),y_(3),z_(3))` be the positions of masses 1kg, 2KG, 3KG and let the co-ordinates of centre of MASS of the three particle system is `(x_(cm),y_(cm),z_(cm))` respectively `x_(cm)=(m_(1)x_(1)+m_(2)x_(2)+m_(3)x_(3))/(m_(1)+m_(2)+m_(3))` `implies2=(1xxx_(1)+2xxx_(2)+3xxx_(3))/(1+2+3)`, (or) `x_(1)+2x_(2)+3x_(3)=12"".......(1)` Suppose the fourth particle of mass 4kg is placed at `(x_(4),y_(4),z_(4))` so that centre of mass of new system SHIFTS to (0,0,0). For X-co-ordinate of new centre of mass we have `0=(1xxx_(1)+2xxx_(2)+3xxx_(3)+4xxx_(4))/(1+2+3+4)` `impliesx_(1)+2x_(2)+3x_(3)+4x_(4)=0...................(2)` From equation (1) and (2) `12+4x_(4)=0impliesx_(4)=-3` Similarly, `y_(4)=-3andz_(4)=-3` Therefore 4 kg should be placed at (-3,-3,-3). |
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| 26. |
The definition of volume coefficient of a gas is different from the definitions of the volume coefficient of a solid or a liquid. Why? |
| Answer» Solution :In case of a gas, the initial volume at `0^(@)C` is to be taken whereas in case of SOLIDS and LIQUIDS, the initial volume at the initial temperature can betaken SINCE the CHANGES in volumes of solids and liquids with temperature are very small whereas the changes in volume of the gases are not so small. | |
| 27. |
In case of propagation of longidudinal waves, angle between directions of velocity of particle and velocity of wave is 0^(@) or 180^(@). |
| Answer» SOLUTION :TRUE . (Becaue these directions are either PARALLEL or ANTIPARALLEL). | |
| 28. |
A symmetrical lamina of mass M consists of a square shape with a semicircular section over each of the edge of the square as shown,. The moment of inertia of the lamina about an axis passing through the centre of mass and perpendicular to the plane is 1.6" Ma"^(2). The moment of inertia about the tangent AB n the plane of the lamina is (x+0.8)"Ma"^(2). where 'x' is |
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Answer» |
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| 29. |
The position-time graoh of a unirom motion in one dimension of a body can have negative slope. When the speed of body decrease with tiem, the position-time graph of the moving body has begative slope . |
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Answer» (a) Statement-1 is true , Statement-2 is true , Statvement -2 is CORRECT EXPLANATION of Statement-1 . |
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| 30. |
On investigation of light from three different stars A , B and C , it was found that in the spectrum of A the intensity of red colour is maximum, in B the intensity of blue colour is maximum and in C the intensity of yellow colour is maximum. From these observations it can be concluded that |
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Answer» The temperature of A is MAXIMUM, B is MINIMUM and C is INTERMEDIATE |
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| 31. |
A polyatomic gas with n degrees of freedom has a mean energy per molecule given by |
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Answer» `N KT//N_A` |
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| 32. |
Having all units in atomic standards in more useful. Expalin. |
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Answer» Solution :An atomic MASS unit (SYMBOLIZED AMU or amu) is defined as precisely `1//12` the mass of an atom of carbon-12. The carbon-12 (C-12) alom has six protons and six neutrons in its nucleus. In imprecise terms, one AMU is the AVERAGE of the proton rest mass and the neutron rest mass. This is approximately `1.67377 XX 10^(-27)` kilogram (kg), or `1.67377 xx 10^(-24)` gram (g). The mass of an atom in AMU is roughly equal to the sum of the number of protons and neutrons in the nucleus. The AMU is used to express the relative masses of elements, and thereby differentiate between, various isotopes of elements. Thus, for example, uranium-235 (U-235) has an AMU of approximately 235, while uranium-238 (U-238) is slightly more massive. The difference results from the fact that U-238, the most abundant naturally occurring isotope of uranium, has three more neutrons than U-235, an isotope that has been used in nuclear reactor and atomic bombs. |
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| 33. |
A horizontal force ''F'' produces an acceleration of 6m//s^(-2) on a block resting on a smooth horizontal surface. The same force produces an acceleration of 3m//s^(-2) on a second block resting on a smooth horizontal surface. If the two blocks are tied together and the same force acts, the acceleration produced will be |
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Answer» `9m//s^(-2)` |
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| 34. |
A rod AB of mass M is attached as shown in figure to a spring of constant k. A small block of mass mis placed on the rod at its free end A. In equilibrium, rod is horizontal, i.e., spring is stretched.(a) If end A is moved down through a small distance d and released, determine the period of vibration, (b) Determine the largest allowable value of d if the block m is to remain at all times in contact with the rod. |
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Answer» If `x_0` is the extension of the SPRING here , `x_0 = l theta and x=) = btheta` RESTORING FORCE in the spring = `kx_0` Restoring torque `tau= (Kx_0) b = Kb^2 theta` But `tau = I ALPHA ` where `I = ((Ml^2)/(3) + mL^2) (M/3 + m) l^2 alpha = - kb^2 theta` `alpha = - {(Kb^2)/(M/3 + m)l^2}theta = 2pi sqrt(alpha/theta)` |
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| 35. |
Zero error of an instrument introduces |
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Answer» SYSTEMATIC error |
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| 36. |
A particle moves so that position vector is given by vecr = cos omega t hat(x) + sin omega t hat(y). Where omega is a constant. Which of the following is true? |
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Answer» VELOCITY and ACCELERATION both are PERPENDICULAR to `vecr` |
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| 37. |
What is torque constant ? State its unit. |
| Answer» SOLUTION :Torque constant is equal to the moment of the couple required to PRODUCE unit angular displacement. Its unit is `NM rad^(-1)`. The RESTORING couple `prop` displacement `tau prop theta, tau=- c theta, c` is CALLED torque constant. | |
| 38. |
A laser light beamed at the Moon takes 2.56s and to return after reflection at the Moon's surface. What will be the radius of lunar orbit? |
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Answer» Solution :t = 2.54s `:.` t = TIME taken by laser BEAM to go to the Moon = `t/2` DISTANCE between Earth and Moon = `d = c xx t/2 = 3 xx 10^(8) xx (2.56)/(2) = 3.84 xx 10^(8)` m |
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| 39. |
Select the correct alternative: Work done by a body against friction always results in a loos of its kinetic/potential energy. |
| Answer» SOLUTION :KINETIC ENERGY | |
| 40. |
For a body rolling along a level surface, the translational and rotational K.E are equal. The body is |
| Answer» Answer :C | |
| 41. |
The changes produced by the deforming forces in a rigid body are |
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Answer» very large |
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| 42. |
A tungsten wire of length 20cm is stretched by 0.1cm. Find the strain on the wire. |
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Answer» 0.002 |
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| 43. |
What is the frequency of variation of kinetic energy of SHM. When the frequency f ? |
| Answer» SOLUTION :Frequency of VARIATION of KINETIC energy and energy is 2F. | |
| 44. |
The motion which is not simple harmonic is : |
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Answer» oscillation of a LIQUID column is a U-tube |
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| 45. |
If vecA= (2hati+3hatj)" and "vecB = (hati-hatj) then component of vecA perpendicular to vector vecB and in the same plane is |
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Answer» `(5)/(2)(hati+hatj)` |
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| 46. |
State the expression for net compliance of a system containing n springs connected in Series and |
| Answer» SOLUTION :When n SPRINGS are CONNECTED in series NET compliance `C_(S) = overset(n) underset(i=1)sum C_(i)` | |
| 47. |
From kinetic theory of gases, show that Moon cannot have atmosphere (Assume k=1.38xx10^(-23)JK^(-1),T0^@C=273K). |
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Answer» Solution :We KNOW that `1/2mV^2_(rms)=3/2kT` `:.V_(rms) = sqrt((3kT)/m)` mass = `3.33xx10^(-27)kg` Temperature = 0+273=273K Boltzmann constant `k = 1.38xx10^(-23)J//K` `:.V_(rms)=sqrt((3xx1.38xx10^(-23)xx273)/(3.33xx10^(-27)))` `= sqrt((3xx1.38xx273)/(3.33)xx10^4)` `=18.422xx10^2` `V_(rms) =1.842xx10^3ms^(-1)` The value of `v_e` is less than the velocity of gass present on mon . HENCE MOON cannot have an ATMOSPHERE. |
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| 48. |
A body is thrown with the velocity u=12.0ms^(-1) at an angle of alpha=45^(@) to the horizon. It touches to the ground at the distances from the point where it was thrown. From what height h should stone be thrown in a horizontal direction with the same initial velocity u so that it all at the same spot? |
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Answer» |
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| 50. |
A simple pendulum has time period T_(1). The point of suspension is now moved upward according to the relation y= kt^(2)(k=1 ms^(-2)) where y is the vertical diplacement. The time period now becomes T_(2). What is the ration (T_(1)^(2))/(T_(2)^(2)) ? Given g=10 ms^(-2) |
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Answer» Solution :In FIRST case, `T_(1)=2PI sqrt(mug) ""...(1)` In second case, displacement, `y= KT^(2)` upward velocity `v=(dy)/(dt)=2kt` , upward acceleration, `a=(dv)/(dt)` `=2k=2xx1=2 ms^(-1)` `:.` Time period, `T_(2)=2pi sqrt((l)/(g+a))""...(2)` Hence `(T_(1)^(2))/(T_(2)^(2))=(4PI^(2)l)/(g)xx((g+a))/(4pi^(2)l)=(g+a)/(g)` `=(10+2)/(10)=(6)/(5)` |
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