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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 heavy wheel of radius 20 cm and weight 10 kg is to be dragged over a step of height 10 cm, by a horizontal force F applied at the centre of the wheel. The minimum value of F is |
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Answer» 20 kgwt |
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| 2. |
The displacement of a particle of mass 3gm executing S.H.M is given by y = 3 sin (0.2t) in S.I units. The K.E of the particle at a point which is at a distance equal to 1/3 of its amplitude from its mean position is |
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Answer» `12 XX 10^(3) J` |
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| 3. |
Crane is British unit of volume (One crane =170.474 litre). Convert crane into Si unit. |
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Answer» `0.170474m^(3)` SI UNIT of VOLUME of `m^(2)` Using1 litre `=10^(3)cm^(3)` or 1 litre `=10^(-3)m^(3)` `170.474 "litre" =170.474xx10^(-3)m^(3)=0.170474m^(3)` |
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| 4. |
(A): Mean free path of a gas molecules varies inversely as density of the gas. (R): Mean free path varies inversely as pressure of the gas. |
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Answer» Both (A) and ( R) are TRUE and (R ) is the correct explanation of (A) |
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| 5. |
The kinetic energy K of a particle moving along a circle of radius R depends on the distance covered s as K=as^(2). The force acting on the particle is |
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Answer» |
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| 6. |
The heat required to increase the temperature of 4 moles of a mono - atomic ideal gas from 273 K to 473 K constant volume is ………….. . |
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Answer» 200 R |
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| 7. |
A body is throw up with a velocity 'u'. It reaches maximum height 'h'. If its velocity of projection is doubled the maximum height it reaches is___ |
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Answer» 4h |
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| 8. |
A football player kicks a 0.8 kg ball and imparts it a velocity 12 ms^(-1) the contact between the foot and ball is onlyfor one sixtieth ofa second find the average kicking force |
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Answer» SOLUTION :Given: Mass of the ball = 0.8 kg Final velocity `(V) = 12 ms^(-1)`and time`t = 1/60 s ` Initial velocity = 0 We know the average kicking force ` F = ma = (m(v-u))/(t) = (0.8(12-0))/((1/60))` ` F = 576 N` |
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| 9. |
Free downwared motion of body is stopped in 1 s on application of an upward force when the body has fallen through 10 m. Another force would have stopped the body in 2 s. find the ration between the two forces. (g = 9.8 m cdot s^(-2) ) |
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| 10. |
The temperature of a perfect black body is 1000 K and its area is 0.1 m^(2). If sigma=5.67xx19^(-8)Wm^(-2)K^(-4) calculate the heat radiated by it in 1 minute? |
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Answer» Solution :According to Stefan.s LAW if E is the energy RADIATED in 1 SEC by unit surface area then `E=sigmaT^(4)` `therefore` Total energy radiated, `E=A(sigmaT^(4))` `t=0.1xx5.67xx10^(-8)xx1000^(4)xx60` = `34.02xx10^(4)J` |
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| 11. |
Among solids,liquids and gases which can have all the three moduli of elasticity? |
| Answer» SOLUTION :Solids.Genrally ,LIQUIDS and GASES have only BULK MODULUS. | |
| 12. |
Choose the add one out : |
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Answer» Sound boards or stringed instruments |
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| 13. |
A force of 200 N compresses a steel rod of length 1.5 m and area of cross section 3 mm through a distance of 4 mm. Find the work done. Work done |
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Answer» Solution :WORK done `=(1)/(2)` (Loan) (CHANGE of length) `=(1)/(2) (F)(DeltaL)=(1)/(2) (200) ((4)/(10^(3)))=0.4` Joule, So workdone `=0.4` Joule |
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| 14. |
A cone of height h and semivertical angle alpha is just held in equilibrium against a smooth vertical wall by a string attached to the apex and tied to the wall at the other end. Calcualate the length of the string. |
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| 15. |
A gas having a pressure of 750 mm of Hg occupies a volume of 300 times 10^(3)mm^(3)" at "52^(@)C. Find the volume of the same gas at S.T.P. |
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Answer» Solution :Initial pressure `P_(1)=750` mm of Hg , Final pressure `P_(2)=760` mm of Hg Initial temperature `t_(1)=52^(@)C, T_(1)=273+52=325K` Final temperature `t_(2)=0^(@)C, T_(2)273K` , Initial VOLUME `V_(1)=300 times 10^(3)mm^(3)` Final volume `V_(2)=?` From the gas equation, `(P_(1)V_(1))/T_(1)=(P_(2)V_(2))/T_(2)" (or) "V_(2)=(T_(2)P_(1))/(T_(1)P_(2))V_(1)=273/325 times 750/760 times 300 times 10^(3)` `=248684mm^(3)=248.7 times 10^(3)mm^(3)` |
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| 16. |
A person measures the time period of a simple pendulum inside a stationary lift and finds it to be .T.. If the lift starts accelerating down wards with an acceleration g/3, the time period of the pendulum will be |
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Answer» `SQRT(3)T` |
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| 17. |
A body of mass 4kg is projected vertically up with a velocity of 20 ms^(-1) . If the energy spent in over coming air resistance is 200J, the maximum height attained by it is (g = 10 ms^(-2)) |
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Answer» 10 m |
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| 18. |
Two bodies of equal mass are at rest, side by side. A constant force F is applied on the first body while at the same instant an impulsive force, producing an impulse I is applied in the same direction on the second body. Determine the time taken by them, in terms of F and I, to be side by side again. |
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Answer» Solution :Let the MASS of each body be m, and the times when they are side by 0 and t s. Acceleration of the first body due to F, a = `(F)/(m)`. `therefore` DISPLACEMENT of the first body in time t, starting from rest, `s_(1) = (1)/(2)cdot (F)/(m)cdot t^(2) = (Ft^(2))/(2m)` The change in momentum of the second body due to impulse, I = change in momentum = mv - mu = mv - m `XX` 0= mv or,`v = (I)/(m)` As no other force acts on the second body, it moves with this constant velocity (v) for t s, and covers a distance `s_(2)`. `therefore "" s_(2) = vt = (I t)/(m)` According to the problem `s_(1) = s_(2)` `therefore ""(Fr^(2))/(2m) = (I t)/(m) `[ from (1) and (2) ] `therefore "" t = (2I)/(F)` . |
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| 19. |
Thesuperposition of two progressive sound waves of equal speed and amplitude but of slightly different frequencies produces ____ . [Fill in the blank] |
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Answer» |
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| 20. |
A screw gauge and a sphermoeter can measure distances upto |
| Answer» Answer :(c ) | |
| 21. |
Two particles executing SHM of the same amplitude and frequency on parallel lines side by side. They cross one another when moving in opposite directions each time their displacement is sqrt(3)/2 times their amplitude. What is the phase difference between them? |
| Answer» SOLUTION :`60^@` (or) `pi//3` RADIAN | |
| 22. |
Distinguish between elastic and inelastic collisions. |
| Answer» Solution :In an elastic collision between the bodies under ISOLATION total linear momentum and kinetic ENERGY will be conserved whereas in the case of inelastic collision only linear momentum will be conserved but not the total kinetic energy. In the case of a PERFECT elastic collision, the COEFFICIENT of restitution will be unity but for a perfectly inelastic collision, the coefficient of restitution will be zero. In general, collisions are neither perfectly elastic nor inelastic. The coefficient of restitution for an inelastic for an inelastic collision, lies between 0 and 1. In an elastic collision there will be no loss in the net kinetic energy of the system. The loss in hte kinetic energy in an inelastic collision `=(1)/(2)((m_(1)m_(2))/(m_(1)+m_(2)))v_(1i)^(2)`. | |
| 23. |
A simple harmonic oscillator of period 6 second has 6 joule potential energy when its displacement is 3 cm. Calculate (i) force constant and (ii) average kinetic energy when the amplitude is 5 cm. |
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| 24. |
The gravitational field in a regioin is given byvecE=(5hati + 12hatj)N//Kg. The change in gravitational potential energy if a particle of mass 1 Kg in taken from the origin to the point (12m, 5m). |
| Answer» ANSWER :C | |
| 25. |
A particle is projected from horizontal ground with speed 5ms^(-1) at 53^(@) with horizontal. Find time after which velocity of particle will be 45^(@) with horizontal: |
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Answer» `(1)/(10)` SEC  `5cos 53^(@)=v COS 45^(@)` `v SIN 45^(@)=5sin 53^(@)-gt` |
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| 26. |
Radioactive dating is used for measuring long time intervals of the order of |
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Answer» `10^(17)s` |
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| 27. |
A man stands on a rotating platform with his arms outstretched horizontally holding a 5 kg weight in each hand. The angular speed of the platform is 30rpm. The man then brings his arms back to his body with the distance of each weight from the axis changing from 0.90m to 0.20m. The moment of inertia of the man together with the platformmay be taken to be constant and equal to 7.6kgm^2 What is his new angular speed ? |
Answer» Solution :From the LAW of conservation of angular MOMENTUM  `Iomega=I'omega'` i.e `(2xx5xx0.9+7.6)30=(2xx5xx0.2xx0.2+7.6)W'` `:.omega'=(15.7xx30)/(8)=58.875` i.e `omega'~~59rpm` |
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| 28. |
When the tenstion on a wire is 4N its length is l_(1). When the tension on the wire is 5N its length is l_(2). Find its natural length. |
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Answer» `5l_(1)-4l_(2)` |
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| 29. |
A man stands on a rotating platform with his arms outstretched horizontally holding a 5 kg weight in each hand. The angular speed of the platform is 30rpm. The man then brings his arms back to his body with the distance of each weight from the axis changing from 0.90m to 0.20m. The moment of inertia of the man together with the platformmay be taken to be constant and equal to 7.6kgm^2 Is K.E conserved in the process ? If not, from where does the change come about ? |
Answer» Solution :From the LAW of conservation of angular momentum  `Iomega=I'OMEGA'` i.e `(2xx5xx0.9+7.6)30=(2xx5xx0.2xx0.2+7.6)w'` `:.omega'=(15.7xx30)/(8)=58.875` i.e `omega'~~59rpm` |
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| 30. |
A toycart is designed in sucha way that aftermoving 500 cm forward it reversed 300 cmback at a rateof 100 cm per five seconds. Findthe timetaken by the cart to covera distanceof 1 m. |
| Answer» Solution :To coverthe distanceof 1m,the cart will ACTUALLY COVER ` 5 xx 500 + 5 xx 300 = 4000` CM = 40 .Timetaken to cover the distanceof 4000 cm will be 200 seconds. | |
| 31. |
What type of motion is represented by equation Delta s= v Delta t ? |
| Answer» SOLUTION :UNIFORM MOTION. | |
| 32. |
Derive an expression for elastic potential energy per unit volume stored for the wire is 1/2 xx stress xx strain. |
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Answer» Solution :Young MODULUS `Y= ( F//A)/(x//L)` where x = length of wire increased `therefore F = ((YA)/(L ))x` Now, work done to be done to increae length dx, `dW = Fdx` `= ((YA)/(L)) x dx` `therefore `Work to be done to increase the length l against RESTORING FORCE, `W = int _(0) ^(l) ((YA)/( L ))d dx` `= (AY)/(2L) l ^(2)` Which is the elastic potential energy stored in wire. `therefore U= (AY)/(2L) l ^(2)` `therefore ` Energy stored per unit volume `= (U )/(LA)` `=1/2 (Yl ^(2))/(L ^(2))` `=1/2 xx (("stress")/("STRAIN")) xx ("strain") ^(2)` `=1/2 xx ` stress `xx` strain |
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| 33. |
Identify the false statement from the following. |
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Answer» Work - energy theorem is not INDEPENDENT of Newton.s second law. |
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| 34. |
A brass wire 1.8 m long at 27 ^(@) C is held taut with little tension between two rigid supports. If the wire is cooled to a temperature of- 39 ^(@) C. what is the tension developed in the wire, if its diameter is 2.0 mm ? Co-efficient of tear expansion of brass= 2.0 xx 10^(-5) K^(-1), Young's modulus of brass =0.91 xx 10^(11) Pa. |
| Answer» SOLUTION :`3.8 XX 10^(2) N` | |
| 35. |
A container holds 10^(26) molecules //m^(3), each of mass 3 xx 10 ^-27 Kg. Assume that /6 of the molecules move with velocity 2000 m//s directly towards one wall of the container while the remaining 5//6 of the molecules move either away from the wall or in perpendicular direction, and all collisions of the molecules with the wall are ealastic |
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Answer» number of molecules HITTING `1 m^2` of the WALL every SECOND is `3.33 xx 10^28` |
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| 36. |
A ball of mass 400 gm is dropped from a height of 5 m . A boy on the ground hits the ball vertically upwards with a bat with an average force of 100 newton so that it attains a vertical height of 20 m . The time for which the ball remains in contact with the bat is [g=10m//s^(2)] |
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Answer» `0.12s` |
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| 37. |
(A) : Tissue of aorta is an elastomer.(R) : Strain-stress curve is non linear. |
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Answer» Both (A) and (R) are TRUE and (R) is the CORRECT explanation of (A) |
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| 38. |
A spherical hole is made in a solid sphere of radius R. The mass of the sphere before hollowing was M. The gravitational field at the centre of the hole due to remaining mass is |
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Answer» ZERO |
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| 39. |
Which one of the following plots represents the variation of the gravitational field on a particle with distance r due to a thin spherical shell of raduis R? (r is measured from the centre of the spherical shell). |
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Answer»
Inside the shell, F = 0 (for `rltR`) On the surface of the shell, `F=(GM)/(r^2)` (for r = R) OUTSIDE the shell, `F=(GM)/(r^2)` (for `rgtR`) The variation of F with distance r from the centre is as SHOWN in the FIGURE (b). |
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| 40. |
Three particles each of mass 100 g are placed at the vertices of an equilateral triangle of side length 10 cm. Find the moment of inertia of the system about an axis passing through the centroid of the triangle and perpendicular to its plane. |
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Answer» Solution :`m=100 g 100xx10^(-3) KG` side `a=10 CM =0.1 m`. Moment of INERTIA`I=3mr^(2)` `=3xx100xx10^(-3)((10)/(sqrt(3))xx10^(-2))^(2)=10^(-3) kg m^(2)` |
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| 41. |
Which of the following is true in the case of an adiabatic process, where gamma=C_(P)//C_(V) ? |
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Answer» <P>`P^(1-GAMMA)T^(gamma)="CONSTANT"` |
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| 42. |
In the above problem M.I. of system about y-axis passing through centre is ___ |
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Answer» `ML^(2)` |
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| 43. |
Three equal weights of mass m each are hanging on a string passing over a fixed pulley as shown in Fig. What are the tensions in the string connecting weights A to B and B to C? |
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| 44. |
What is a .White dwarf.? |
| Answer» SOLUTION : When the hydrogen available in “red gaint star” exhausts completely, it blows and releases material PARTICLES present in it and becomes relatively dim star known as “white DWARF star”. Its size is `1//10^6`TIMES the size of the original star. | |
| 45. |
The potential energy function for a particle executing linear SHM is given by V(x) =1/2kx^(2) wher e k is the force constant of the oscillator (figure). For k = 0.5 N/m ,the graph ofV(x) versus x is shown in the figure . A particle oftotal energyE turnsbackwhen it reachesx = pm x_(m) . If V and K indicate the PE and KE , respectivelyof the particle at x = +x_(m) , then which of the following is correct ? |
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Answer» V =0 ,K=E At `X = x_(m), v = 0 ,KE = 0 ` From Eqn.(i) `E = pE +0 = PE =V(x_(m)) =1/2 kx_(m)^(2)` |
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| 46. |
Water is allowed to flow through a capillary tube of 10 cm length and 2 cm diameter under a constant pressure difference of 6.5 cm of water level. If 16xx 10^(-2) lit of water flows in one minute, find its coefficient of viscosity? |
| Answer» SOLUTION :0.0009384Poise | |
| 47. |
A thin wire of length l and surface area A is heated to a temperature T. Its electrci resistance is R, emissivity of its surface is e. How much electric current should be maintained through the wire so as. To maintain its temperature at T ? Assume the temperature of surroundings to be negligible compared to T. Use Stefan.s constant as sigma : |
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Answer» `(EA sigmaT^(4))/( R )` |
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| 48. |
Select a TRUE statement from thefolloiving: |
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Answer» YEAR and light year have the same DIMENSIONS. |
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| 49. |
Is it possible for body to have variable velocity but constant speed? Give example. |
| Answer» Solution :YES, it is possible. In horizontal circular MOTION the speed of a PARTICLE is always constant but DUE to the variation in direction continuously, the velocity of a particle varies. | |
