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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 force of (hat(i) + 2hat(j) + 3hat(k))N is acting on a body having position vector (3 hat(i) + hat(j) + 2hat(k)) in the same frame of reference The moment of the force about the origin is |
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Answer» `- HAT(i) - 7hat(J) + 5hat(k)` |
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| 2. |
The coefficient of volume expansion of a solid is x times the coefficient of superficial expansion. Then x is |
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Answer» 1.5 `THEREFORE""gamma =(3)/(2)beta rArr gamma=1.5 beta` `x=1.5` |
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| 3. |
When a wave passes through a given medium, which of following quantities does not depend on the rest ? |
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Answer» VELOCITY |
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| 4. |
The radius of gyration of a body about an axis passing through its centre of mass is 24 cm. Calculate the radius of gyration of the body about a parallel axis passing through a point at a distance of 7 cm from its center of mass. |
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Answer» Solution :`K_(1)=24 cm, r = 7 cm` `I=I_(G)+Mr^(2) "" I_(G)=MK_(1)^(2), I=MK^(2)` `therefore MK^(2)= MK_(1)^(2)+Mr^(2)` `K^(2)=K_(1)^(2)+r^(2)=(24)^(2)+(7)^(2)=576+49=625` `therefore` RADIUS of gyration ` K = sqrt(625)=25 cm` |
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| 5. |
The position vectors particle has length 1m and makes 30^(@) with the x-axis. What are the lengths of the x and y components of the position vector? |
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Answer» Solution :Length of position vector = 1 m, Angle made with X axis =30 `"Length of X component (OB)" = OA cos theta = 1 xx cos 30^(@)` `l_(x)= (SQRT(3))/(2)`m or 0.87m `"Length of Y component (AB)" =OA sin theta =1 x sin 30^(@) = (1)/(2) = 0.5 m. , l_(y)=0.5 m ` 
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| 6. |
W/(mK)is a unit of, |
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Answer» STEFAN's constant |
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| 7. |
Two particles having masses m and 2m are travelling along x-axis on a smooth surface with velocities u_(1) and u_(2), collide. If their velocities after collision are v_(1) and v_(2) , then the ratio of velocities of their centre of mass before and after impact is |
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Answer» `2:1` |
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| 8. |
ABC is a triangular plate of uniform A thickness. The sides are in the ratio shown in the figure.I_(AB), I_(BC), I_(CA) are the moments of inertia of the plated about AB, BC and CA respectively. Which one of the following relation is correct? |
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Answer» `I_(CA)` is maximum |
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| 9. |
The gravitational potential in a region is given by v = 20 (x + y)J/kg. If the magnitude of gravitational force on the particle of mass 0.05 kg placed at the orgin is sqrt(x) in Newton. Find the value of x |
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Answer» |
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| 10. |
A ""^(238)U nucleus emits an alpha-particle and is converted into ""^(234)Th nucleus. If velocity of the alpha-particle is 1.4 xx 10^(7) ms^(-1) calculate the velocity of recoil of remaining ""^(234)Th nucleus. |
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Answer» `2.393 XX 10^(5) m//s` |
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| 11. |
What is the nature of velocity - time graphfor uniform motion ? |
| Answer» SOLUTION :For uniform motion , the velocity - TIME GRAPH is a straight line PARALLEL to time axis . | |
| 12. |
If both the speed and radius of the circular path of a body are doubled, how will the centripetal acceleration change? |
| Answer» SOLUTION :`alpha_c=v^2/r,alpha_c=(2V)^2/(2R)=2alpha_c` | |
| 13. |
Linear expansion is change in length of an object with temperature. The abosolute zero is ……….. |
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Answer» `273.15◦C` |
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| 14. |
A double star is a system of two stars rotating about their centre of mass only under their mutual gravitational attraction. Let the stars have masses m and 2m and let their separation by 1. Theire time period of rotation about their centre of mass will be proportional to |
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Answer» only a & C are TRUE |
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| 15. |
Time period of a particle in S.H.M. Depends on the force constant K and mass m of the particle T=2pisqrtm//k. A simple pendulum for small angular displacement executes S.H.M. approximately. Why then is the time periodof a pendulum independent of the mass of the pendulum ? |
| Answer» Solution :Restoring force in case of simple pendulum is given by `F= (mg)/l y Rightarrow K =(mg)/l` So force CONSTANT itself PROPORTIONAL to` m` as the value of `k` is substituted in the formula, `m` is cancelled out. | |
| 16. |
Explain why (a) To keep a piece of paper horizontal ,you should blow over , not under , it |
| Answer» Solution :When we blow over the of paper , the velocity of AIR increases . As a RESULT , the pressure (P) on it decreases in accordance with the Bernoulli.s THEOREM whereas the pressure below REMAINS the same asatmospheric presseure Pa. Thus , the paper remains horizontal. | |
| 17. |
Calculate the speed with which wafer emerges from a hole in a tank at which the gauge pressure is3 xx10^(5) N//m^(2) ? |
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Answer» Solution :Velocity of efflux = `V= SQRT( 2gh )` But`""P = h rho G or GH = ( P)/(rho.)` `therefore ""v=sqrt(2(P)/(rho))= sqrt((2xx3xx10^(-5))/(1000))= 24.49 m//s` |
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| 18. |
A satellite of mass 400 kg is in a circular orbit of radius 2R about the earth where R is radius of the earth. How much energy is required to transfer it to a circular orbit of radius 4R? Find the changes in the kinetic and potential energies? (R = 6.37xx10^6m) |
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Answer» Solution :Initial total ENERGY is `-(GMM)/(2r_2)=-(GMm)/(8R)=E_2` Final total energy is `-(GMm)/(2r_2)=-(GMm)/(8R)=E_2` The change in the total energy is `DELTAE=E_2-E_1=(GMm)/(8R) rArr DeltaE=((GM)/R^2) (mR)/8` `DeltaE=(gmR)/8=(9.8xx400xx6.37xx10^6)/8=3.13xx10^9` J Change in Kinetic energy =`K_2-K_1=-3.13xx10^9` J Change in POTENTIAL energy = `U_2-U_1=-6.25xx10^9` J |
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| 19. |
The surface area of a rectangular film of a liquid is extended from 10 cm xx" 6 cm to 12 m" xx 10 cm. If the work done during this process is 6 xx 10^(-4)J and surface tension of liquid is n xx 10^(-2)" N/cm", find the value of n. |
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Answer» Solution :`triangleA=` INCREASE of area `=2(12 xx 10-10 xx 6)cm^(2)` `=120cm^(2)=120 x 10^(-4) m^(2)` Surface tension `=("WORK DONE")/("Increase in area")` `=(6 xx 10^(-4))/(120 xx 10^(-4))` |
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| 20. |
A string is hanged to strong support O as shown in figure. It is wrapped to a disc of mass m and radius R at its other end. This string is weightless and unstretchable then find the linear acceleration of centre of mass of disc. |
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Answer» SOLUTION :Tension produced in the string is shown in FIGURE. Linear equation of motion of disc is `ma=mg-T` `therefore T=m(g-a)….(1)` If angular acceleration of disc `alpha`, then `Ia=TR…..(2)` but `alpha=(a)/(R )` for disc, `I=(mR^(2))/(2)` `therefore (mR^(2))/(2).(a)/(R)=m(g-a)R` Putting value of T from equation (1) `therefore (a)/(2)=g-a` `therefore (3)/(2)a=g` `therefore a=2//3g` 
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| 21. |
Force F on the particle of mass 0.1 kg varies with distance x as shownin figure . If particle with distancex as shown in figure .If particlemove from rest x = 0 , that at x = 12 cm , what will be its velocity ? |
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Answer» Solution :Work W = Area of isoscles trapezoid OABC ` =1/2 {:{("sumof sides"),(of " parallelogram"):}}xx{("perpendicular DISTANCE"),("between sides of parallelogram"):}}` ` =1/2 (AB +OC) xx(BD)` ` =1/2 (4+12)xx(10)` ` = 80 J ` `rArr` Now according to work energy theorem , `W =K_(f) -K_(0)` ` :.80 =1/2 mv_(f)^(2) -1/2mv_(i)^(2)` ` :.80 =1/2 mv_(f)^(2) "" [ :. v_(i) = 0] ` ` 80 =1/2 xx0.1 xxv^(2)` ` :. 1600 =v^(2)` ` :. v = 40 m^(-1)` |
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| 22. |
We are familiar with Newton's lows of motion.Using the above law explain. Law of conservation of linear momentum |
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Answer» Solution :`VEC F= d vec P/dt` when `vec F= O, vec p `is a CONSTANT. If no external force acts on a system, the linear momentum of the system remains constant. |
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| 23. |
The process in which heat transfer is by actual movement of molecules in fluids such as liquids and gases is called : |
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Answer» THERMAL conductivity |
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| 24. |
If different types of pendulums are taken to the moon, the time period will change for |
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Answer» SIMPLE PENDULUM |
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| 25. |
A large open tank has two holes in the wall. One is a square hole of side 'L' at a depth 'y' from the top and the other is a circular hole of radius R at a depth '4y' from the top. When the tank is completely filled with water, the quantities of water flowing out per second from the two holes are the same. Then value of R is : |
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Answer» `(L)/(sqrt(2PI))` |
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| 26. |
Assertion : Usage of ball bearing between two moving parts in a machine is a common practice Reason : Ball bearing reduce vibrations and provide good stability Which one of the following statement is a correct statement |
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Answer» ASSERTION is TRUE and reason is true and EXPLAINS assertion |
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| 27. |
A steel tape is callibrated at 20^(@)C. When the temperature of the day is -10^(@)C, the percentage error in the measurement with the tape is (alpha=12" "10^(-6)//""^(@)C) |
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Answer» `3.6%` |
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| 28. |
A drum of radius R and mass M, rolls down without slipping along an inclined plane of angle theta, The frictional force …………. |
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Answer» Dissipats energy as heat  When a cylinder rolling without SLIPPING on the SURFACE of slope then total work done by the friction FORCE is zero. `W_("total")=0` Now `W_(("translational motion"))+W_(("rotational motion"))=0` `therefore DeltaK_(("translational motion"))+DeltaK_(("rotational motion"))=0` `therefore DeltaK_(("translational motion"))-DeltaK_(("rotational motion"))=0` |
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| 29. |
The parameter (mQ^(4))/(epsilon_(0)^(2)h^(2)) has the dimensions of ( m = mass Q = charge in_(0) = Permittivity and h = Planck's constant ) |
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Answer» Wavelength |
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| 30. |
When a person is in a lift accelerated upwards or downwards, do force of gravity and normal reaction on the person form action and reaction pair? |
| Answer» SOLUTION :No, because they are not EQUAL and OPPOSITE. | |
| 31. |
Let V and E denote the gravitational potential and gravitational field at a point . It is possible to have (a)V=0 and E=0, (b)V=0 and E ne 0 (c)V ne 0 and E=0 , (d)V ne 0 and E ne 0 |
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Answer» only a,B are TRUE |
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| 32. |
If the atmospheric pressure is 76cm of mercury, at what depth of water the pressure will becomes 4 atmospheres ? |
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Answer» 31 m |
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| 33. |
Two cyclists, moving with equal speeds of 10//kmhr, are approaching each other along a straight road. When the distance between them is 20km a fly starting from cycle , keeps on flying alternatively from one cycle to the other. If the fly has a constant speed of 40//hr, find the total distance travelled by the fly before the cyclists meet is |
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Answer» SOLUTION :Relative velocity of cyclists of approaching =`20km//hr` TIME taken to meet the cyclists`=(20)/(20)=1 HOUR` Distance travelled by fly =`"speed"xx"time"` `=40xx1=40km.` |
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| 34. |
(A): Magnitude of most probable velocity of gas molecules is equal to most probable speed of the molecules. (R): Most probable velocity is most probable speed in the given direction, |
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Answer» Both (A) and ( R) are true and (R ) is the CORRECT EXPLANATION of (A) |
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| 35. |
If for hydrogen C_(P)-C_(V)=m and for nitrogen C_(P)-C_(V)=n, Where C_(P) and C_(V) refer to specific heats per unit mass respectively at constant pressure and constant volume, the relation between m and n is (molecular weight of hydrogen=2 and molecular weight or nitrogen=14) |
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Answer» n=14m |
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| 36. |
A driver can stop his car from the red signal at a distance of 20m when he is driving at 36kmph and 41.25 m when he is driving at 54kmph. Find his reaction time. |
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Answer» Solution :LET t is reaction time of driver during which he MOVES with uniform speed Distance covered during reaction time `=S_(1)=ut` As he applies BRAKES, distance covered before coming to rest is `S_2=u^2/(2a)` TOTAL distance covered is `S=ut+u^(2)/(2a)` `20=10t+(100)/(2a).....(1)` `41.25=15t+(225)/(2a)......(2)` Solving above EQUATIONS 3.75=7.5t t=0.5s |
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| 37. |
Particles of masses 1 kg and 3 kg at (2i+5j+13 k) m and (-6i+4j-2k)m then instantaneous position of their centre of mass is |
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Answer» `(1)/(4)(-16i+17j+7k)m` |
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| 38. |
When impurities are added to a liquid it's surface tension a) always increases b) always decreases c) If impurities are sparingly soluble surface tension decreases d) If impurities are highly soluble surface tension increases |
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Answer» a, C are correct |
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| 39. |
A simple pendulum with a metal bob has a time period T. Now the bob is immersed in a liquid which is non viscous. Thus the time period is .3T. .Then the ratio of densities of metal bob and that of liquid is |
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Answer» `8:9` |
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| 40. |
Two cars start in a race with velocities u_1 and u_2and travel in a straight line with acceleration 'a' and b. If both reach the finish line at the same time, the range of the race is |
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Answer» `(2(u_1-u_2))/((BETA - ALPHA)^2) (u_1 beta - u_2 alpha)` |
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| 41. |
Define 'Plasticity' ? |
| Answer» Solution :If a BODY does not regain its ORIGINAL SHAPE and size after removal of the deforming force, it is said to be a plastic body and the PROPERTY is called plasticity. Example : Glass. | |
| 42. |
A upersonic jet plane of Mach 1.5 is sighted overhead. How far will it be after 10 s ? (Velocity of sound = 340 m s^(-1)) |
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Answer» |
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| 43. |
Wheels are made circular. Why? |
| Answer» SOLUTION : ROLLING FRICTION is LESS than SLIDING friction. | |
| 44. |
Which one of the following statement is correctfor the following situation Assertion : Frictional forces are conservative forces Reason : Potential energy is associated with frictional forces |
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Answer» ASSERTION is TRUE and reason is FALSE |
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| 45. |
If the surface tension of water is 0.06 Nm^(-1), then the capillary rise in a tube of diameter 1 mm is (angle of contact = 0^@) ………….. . |
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Answer» 1.22 cm |
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| 46. |
An ideal gas follows a process VT = constant where V and T denote volume and absolute temperature. How does the temperature and volume depend on pressure ? |
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Answer» <P> |
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| 47. |
A wheel at rest has M.I. (2)/(pi^(2))"kg m"^(2). It is rotated by a 60 W motor for one minute. The number of rotations made by the wheel in one minute is |
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Answer» 90 |
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| 48. |
Name a process in which momentum change but K.E. does not |
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Answer» |
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| 49. |
Figure shows a block A on a smooth surface attached with a spring of force constant k to the ceiling . In this state spring is in its natural length l. The block A is connected with a massless and frictionless string to another identicalmass B hanging over a light and smooth pulley . Find the distance moved by A before it leaves contact with the ground . |
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Answer» Solution :Due to WEIGHT of block B, it moves down and pulls the block A now as block A and B move , spring gets stretched and BECOMES INCLINED as its lower end is attached to the block A . It will break off from the ground below it when the VERTICAL component of the spring force on block A will balance its weight mg Let it happens when A moves by a distance as shown in figure. At this instant let the spring be inclined at an angle `theta` with the vertical. If the stretch in the spring at this instant is x, then it is given as `x=l sec theta -l"or" x =l(sec theta - 1)`.....(1) If MASS A breaks off from ground below it , we have `kx cos theta =mg`.....(2) From equation (1)and (2) substituting the value of x, we get `kl(sec theta -1)cos theta =mg "or " kl(1-cos theta)=mg "or" cos theta=1-(mg)/(kl)"or" tan theta=[k^(2)l^(2)(kl-mg)^(2)]^(1//2)/(kl-mg)` At this instant the distance travelled by mass A and B is given by `s=l tan theta"(or)" s=l[k^(2)l^(2)(kl-mg)^(2)]^(1//2)/(kl-mg)` |
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| 50. |
Twomasses M_(1)and m_(2)are experiencing the sameforcewhere m_(1)ltm_(2)the ratioof theiracceleration (a_(1))/(a_(2))is |
| Answer» Solution :greater than 1 | |