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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. |
For a body rolling along a level surface, without slipping the translational and rotational kinetic energies are in the ratio 2: 1. The body is |
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Answer» HOLLOW SPHERE |
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| 2. |
A larger drop of water breaks up into a large number of small droplets. Does the surface energy increase ? |
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Answer» Solution :In this case, the surface energy will increase. It can be SHOWN bycalculation that the TOTAL surface area of the smaller droplets of water is greater than the surface area of the large DROP. So, during the breaking up of a large drop of water into many small droplets, the surface area INCREASES. So, increase in surface area`xx` surface TENSION = increase in surface energy. |
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| 3. |
One end of a light spring of spring constant k is fixed to a wall and the other end is tied to a block placed on a smooth horizontal surface. In a displacement, the work done by the spring is (1)/(2) kx^(2). The possible cases are (a) The spring was initially compressed by a distance x and was finally in its natural length (b) it was initially steched by a distance x and finally was in its natural length (c ) it was initially in its natural length adn finally in a compressed position. (d) it wasinitially in its natural length and finally in a stretched position. |
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Answer» a, B are correct |
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| 4. |
Choose the correct statement (s) about gravitational force |
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Answer» It FORMS action reaction pair |
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| 5. |
A chargeparticlehavingcharge q expericenec a F_(1)q=(-hatj+hatk)Nin amagneticfield B when is hasvelocity v_(1)=(1.0)hati(m)/(s). Theforcebecomes F=q(hati-hatl) whenthevelocity is charged to F=q(hati-hatl) magnetic induction vector atthat point is |
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Answer» `(hati+hatj+ HATK)T` |
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| 7. |
If the kinetic energy of a body ia fourtimes it mementum, its velocity is |
| Answer» Answer :D | |
| 8. |
Describe an experiment to explain the phenomenon of interferece ofwaves ? |
Answer» Solution :Let US consider a SIMPLE instruement to demonstrate the interference of sound waves as shown in figure.  A sound wave from a loudspekar S is passed through the tube P. this looks like a T-shaped junction. In this case, half of the sound energy is sent in one DIRECTION and ther remaining half is sent in the OPPOSITE direction. Hence half is sent in the opposite directions. Hence, the sound waves that reach the receiver R can travel along either of twopaths. Thee distance covered by the sound wave along any path from the speaker to receiver is called the path length. From the above figure, iti is noticed that the lower path length is FIXED but the upper path length can be varied by sliding the upper tube i.e., varied. The difference in path length is known as path difference, `Delta r=|r_(2)-r_(1)|` |
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| 9. |
Radius of …………..of a body about a given axis is equal to…………of the constituent particles of the body…………… . |
| Answer» SOLUTION :gyration, root MEAN SQUARE DISTANCE , from the AXIS of rotation. | |
| 10. |
Consider the system shown in figure. We know the masses of bodies : m = 1 kg, M = 3 kg. The distance AB = BC = H//2 are covered in equal time intervals by the body of mass m and at B it undergoes an elastic collision with a stationary body of mass m_(0) (unknown). Time after this collision when the string in pu,,ey 2 becomes tight again is t_(0). t_(0) is second. t_(0)^(2) is equal to 1//x. Value of (x)/(10) is. (Given : H = 1m ) |
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Answer» |
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| 11. |
An ideal gas expands isothermally from a volume V_1 to V_2and then compressed to original volume V_1adiabatically. Initial pressure is P_1 and final pressure is P_3 . The total work done is W. Then. |
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Answer» `P_3 GT P_1 gt W gt 0` |
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| 12. |
A particle executes in S.H.M whose displacement equation is y = 5 sin (10 t -pi//3). The minimum time after which the K.E of the particle will be maximum is |
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Answer» `pi/30 ` SEC |
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| 13. |
Particals of masses Ikg and 3kg are at (10i - 7j - 3k) ms^(-1) and (7i - 9j + 6k) ms^(-1) then a instantaneous velocity of their centre of masses |
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Answer» `(1)/(4)(31i-15k)MS^(-1)` |
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| 14. |
According to kinetic theory, every gas consists of a very large number of molecules, which are in a state of incessant random motion. They move in all directions with different speeds and obey Newton's law of motion. The moleculesdo not exert any force of attraction or repulsion on one another except during collision. Read the above passage and answer the following questions : (i)What is the cause of pressure exerted by the gas ? (ii) What values of life do you learn from the kinetic theory ? |
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Answer» Solution :(i) The pressure exerted by the gas is due to continuous bombardment of gas molecules against the walls of the container. (ii) In DAY to daylife, human beings on earth are like teh molecules of a gas. Just as the molecules of a gas move in all directions with different speeds, human beings are busy in activities of their choice at different speeds. just as gas molecules OBEY Newton's laws of MOTION, all human beings have to obey the respective laws of their land. Like the gas molecules, force of attractions or repulsion amongst the human beings ARISE only when their interests clash. |
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| 15. |
A thin prism of 4^@ angle gives a deviation of 2.4^@ What is the value of refractive index of the material of the prism? |
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Answer» 1.6 |
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| 16. |
Two identical vessel are connected by a tube with a valve letting the gas pass from one vessel to the other if the pressure difference is Deltap le 1.1 atm. Initially there is a vacuum in one in one vessel while the other contained an ideal gas at 27^(@)C and 1atm pressure. Then both the vessel are heated to 107^(@)C. Up to what value will the pressure in the first vessel (which had vacuum initially) increase? |
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| 17. |
A square plate of mass M and edge L is shown in fig. The moment of inertia of the plate about the axis in the plane of plate and passing through one its vertex making an angle 15^(@) from horizontal is ("11ML"^(2))/(8x) where 'x' is |
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Answer» |
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| 18. |
Three measurements of the time for 20 oscillations of a pendulum give t_1 = 39.6s, t_2 39.9s and t_3 = 39.5s . The precision in the measurement is |
| Answer» Answer :A | |
| 19. |
On a very hot day, a boy standing at a large distance observers a neon monochromatic lamp hanging at a height h above the ground. He observe the lamp as shown in the figure |
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Answer» at a HEIGHT h |
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| 20. |
Moment of a force about a point is ______ the area of the triangle formed by joining that point the initial point of application of the force and the final point of application of the force. [ Fill in theblank ] |
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Answer» |
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| 21. |
Two satellites of masses m_1 and m_2 (m_1 gt m_2)are revolving the earth in circular orbits of radius r_1 and r_2 (r_1 gt r_2) respectively . Which of the following statement is true regarding their velocities v_1 and v_2 . |
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Answer» `v_1=v_2` |
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| 22. |
A block of mass m_(1) = 1 kg and anothermass m_(2) = 2 kg are placed together ( see figure) on an inclined plane withangle of inclinationtheta . Various values of theta are given in List I . The coefficient of friction between the block m_(1) and the plane is always zero. The coefficient of static and dynamic friction between the block m_(2) and the plane are equal to mu = 0.3 . In List II expressions for the friction on the block m_(2) are given .Match the correct expression of the friction in List II with the angles given in List I , and choose the option . The acceleration due to gravity is denoted by g . [Useful information : tan ( 5. 5^(@)) = 0.1, tan (11. 5^(@)) = 0.2 , tan (16.5 ^(@)) = 0.3] {:(,"List" I ,, "List" II), (P. , theta = 5^(@) , 1., m_(2)g sin theta ) , (Q. , theta= 10^(@) , 2., (m_(1) + m_(2))g sin theta), (R., theta = 15^(@) , 3., mu m_(2)g cos theta), (S., theta = 20^(@) , 4., mu (m_(1) + m_(2))g cos theta):} |
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Answer» P-1 , Q-1 , R-1 , S-3 `f_("max") gt (m_(1) + m_(2) )gsin theta ` `mu_(N) gt (m_(1) + m_(2)) g sin theta ` `0.3 m_(2) g cos theta ge (1 +2) 10 sin theta ` `0.3 xx 2 xx 10 cos theta ge (1 +2) 10 sin theta ` `6 ge 30 TAN theta ` `(1)/(5) ge tan theta "" implies 0.2 ge tan theta ` Now it is CLEAR in case (P) (Q) it will not slip, friction is `(m_(1) + m_(2)) g sin theta `.  `implies f = (m_(1) + m_(2)) g sin theta ` In the case (R) (S) if they MUST slip so friction should be KINETIC i.e., `mu m_(2) g cos theta ` |
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| 23. |
Calculate the power of a crane in watts, which lifts a mass of 100 kg to a height of 10 m in 20 s. |
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Answer» SOLUTION :m = 100 kg h =10 m t = 20 s Power, P = `U/t = (mgh)/t ( :. U = mgh )` `(100 XX 9.8 xx10)/20` `= 5xx98=490W` |
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| 24. |
The cross product of the vectors (2i - 3j + 4k) and (I + 4j -5k) is |
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Answer» `- hat(i) - 14 hat(J) +11 hat(K)` |
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| 25. |
Rotational Kinetic energy of a body is |
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Answer» `(1)/(2) MR^(2)` |
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| 26. |
N//s |
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Answer» ` . 12 m` ` R= C4^^3-1) = C XX 4^2` and ` 4 = C 5^(3-1) = C xx 5^2`. :. ` R/4 = ( 4/5)^2 = 0.64 ` or ` R = 4 xx 0. 64 = 2. 56 m`. |
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| 27. |
which of the following measurements is more accurate- 3.0 m and 3.00 m ? |
| Answer» Solution :in 3.0 m there are two SIGNIFICANT FIGURE while in 3.00 m there are THREE significant FIGURES . Hence the measurement f 3.00 m isore ACCURATE . | |
| 28. |
(A): Acceleration is the rate of change of velecity. (R): A body having nonzere acceleration can have a constant velocity. |
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Answer» Both (A) and (R) are TRUE and (R) is the correct EXPLANATION of (A) |
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| 29. |
The increase in internal energy of a system is equal to the workdone on the system. The process does the system undergoes is .......... |
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Answer» ISOCHORIC |
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| 30. |
When it is raining vertically down, to a man walking on road the velocity of rain appears to be 1.5 times his velocity. To protect himself from rain he should hold the umbrella at an anglethetato vertical. Then tan theta= |
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Answer» `(2)/(SQRT(3))` |
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| 31. |
When a glass capillary tube is dipped in pure water, water rises to a height .h. in the tube. Capillary tube is pushed down till its height above the surface of water is h^(1)[h^(1)lth]. Find the relation between h and h^(1). |
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Answer» Solution :`h=(2Scostheta)/(rrhog)rArrhpropcostheta` `h/h^(1)=(costheta_(1))/(costheta_(2))=(cos0^(@))/(costheta_(2))rArrcostheta_(2)=h^(1)/h` `theta_(2)=cos^(-1)(h^(1)/h)` In the SPECIAL CASE angle of contact will change even if PAIR of solid & liquid are not CHANGED. |
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| 32. |
(A) Within a glass slab, a double convex air bubble is formed . This air bubble behaves like a diverging lens. ( R): Refractive index of air is less than the refractive index of glass. |
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Answer» Both A and R are true and R is the CORRECT EXPLANATION of A |
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| 33. |
The diameter of a wire as measured by a screw gauge was found to be 1.002 cm, 1.000 cm, 1.006 cm .The absolute error in the second reading is |
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Answer» 0.002cm |
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| 34. |
Consider an object at point P along each trajectory shown in column-1 in the direction of arrow shown. Column-2 gives algebraic sign of v_(x), v_(y), a_(x) and a_(y) . |
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Answer» |
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| 35. |
Centripetal force |
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Answer» INERTIAL frame |
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| 36. |
How much pressure should be applied on a litre of water if it is to be compressed by 0.1%? (Bulk modulus of water= 2100 MPa) |
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Answer» <P> Solution :V = 1 litre = `10^(-3)m^(3)``(DeltaV)/(V)=0.10%= (0.10)/(100) = 0.001` `K=(P)/(DeltaV//V)IMPLIES P=(KDeltaV)/(V)=2.2xx10^(9)xx0.001` `P=2.2xx10^(6)Nm^(-2)` |
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| 37. |
Speeds of two identical cars are U and 4U at a specific instant. The ratio of the respective distance in which the two cars are stopped from that instant is |
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Answer» `1:1` |
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| 38. |
What is the temperature of the steel - copper junction in the steady state of the system shown in Fig.11.15. Length of the steel rod= 15.0 cm, length of the copper reod= 10.0 cm, temperarure of the furnace= 300 ^(@) C, temperature of the furnace= 300 ^(@) C , temperature of the other end= 0^(@) C. The are of cross section of the steel rod is twice that of the copper rod. ( Thermal conductivity of steel= 50.2 J s^(-1) m^(-1) K^(-1) , and of copper= 385 J s^(-1) m^(-1) K^(-1)). |
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Answer» Solution : The INSULATING material around the rods reduces heat loss from the sides of the rods. Therefore, heat flows only along the length of the rods. Consider any cross section of the rod. In the steady state, heat flowing into the element MUST EQUAL the heat flowing out of its OTHERWISE there would be a NET gain or loss of heat by the element and its temperature would not be steady. Thus in the steady state, rate of heat flowing across a cross section of the rod is the same at every point along the length of the combined steel-copper rod. Let T be the temperature of the steel-copper junction in the steady state. Then, `(K_(1)A_(1)(300 - T))/L_(1) = (K_(2)A_(2)(T - 0))/L_(2)` where 1 and 2 refer to the steel and copper rod respectively. For `A_(1) = 2 A_(2) , L_(1) = 15.0 cm , L_(2) = 10.0 cm, K_(1) = 50.2 J s^(-1) m^(-1) K^(-1) , K_(2) = 385 J s^(-1) m^(-1) K^(-1) `, we have `(50.2 xx 2 (300 - T))/15 = (385T)/10 ` which gives `T = 44.4^(@) C` |
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| 39. |
What will be the potential energy of a stretched wire? |
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Answer» SOLUTION :Potential energy of a stretched WIRE `=(1)/(2)Fx` Where, F - force,x - displacement |
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| 40. |
High precision instruments are used to eliminate …………….. Error. |
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Answer» personal |
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| 41. |
A uniform rod of length l is pivoted at point A. It struk n=by an horizontal force which delivers an ikmpulse J at a distance c from point A as shown in figure. Impulse delivered by pivot is zero, if x is equal to |
| Answer» Answer :C | |
| 42. |
What is the minimum velocity with which a body of mass m must enter a vertical loop of radius R so that it can complete the loop? |
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Answer» `SQRT(3gR)` |
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| 43. |
Train A 120 m long is moving with 20 m/s. Train B 130 m long is moving with 30 m/s in opposite direction. In what time, train B will cross train A? |
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Answer» 65 Speed of train `B v _(B) = 30 m//s` If both trains moving in opposite, then relative speed, `v = v _(A) +v_(B)` `=20+30 =50m//s` Total LENGTH of both trains, ` l = (120 +130) m = 250 m` TIme TAKEN to cross, `t = (l)/(v) = (250)/(50) =5s` This is not given in options. `therefore ` The correct option is (D). |
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| 44. |
The location of the centre of mass of a sphere is at: |
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Answer» its top |
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| 45. |
If the tension of the wire is increased four times and its length reduced to half the original length the frequency of vibration |
| Answer» Answer :D | |
| 46. |
Determine the speed with which the earth would have rotate on its axis so that a person on the equator would weigh 3(th)/5 as much as present ( R = 6,400km ) |
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Answer» same as at surface |
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| 47. |
Explain supplementary quantities and their unit of SI system. |
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Answer» Solution :There are two SUPPLEMENTARY quantities of SI system. (1) PLANE angle `d theta(2)` Solid angle `d Omega` (1) Plane angle `d theta` : Ratio of arc of CIRCLE and radiusof circle is called plane angle `(d theta)`  From figure plane angle `d theta=("arc")/("radius")(AB)/(r)=(ds)/(r)` Plane angle subtended at centre by arc of circle having length equal to radius is called 1 radian. It is represented as rad. Maximum value of plane angle is `2pi` rad If AB= r then `theta=1` rad `[1^(@)=(pi)/(180) "rad"] and [1 rad=(180)/(pi)` degree] (2) Solid angle ` dOmega:` d by area `(DELTAA)` on spherical surface with centre of sphere is called solid angle `dOmega`  From figure, Solid angle `d Omega=("area")/(("radius")^(2))=(DeltaA)/(r^(2))` Maximum value of solid angle is `4PI` Angle subtended on `1 m^(2)` area on sphere of 1 m radius is called 1 steradian. Its symbol is Sr. If `DeltaA=1m^(2) and r=1 m "then" Omega=1` Sr |
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| 48. |
In winter blankets and quilts warm up after being wrapped around a body. Why? |
| Answer» Solution :The normal temperature of the body is `37^(@)C`. Blankets, QUILTS etc. are not at a lower temperature in WINTER. After being wrapped, they WARM up by taking heat from the body, and after some TIME thermal equilibrium is established. This means that their temperature ALSO increase to `37^(@)C`. | |
| 49. |
A man is stranded in the middle of a perfectly smooth 'island of ice' where there is no friction between the ground and his feet. Under these circumstances |
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Answer» he can reach the DESIRED corner by throwing any OBJECT in the same direction |
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