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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. |
Which physical quantity is represented by the product of motion of inertia and angular velocity? |
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Answer» |
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| 2. |
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. | |
| 3. |
A soap bubble of radius 1 cm expands into a bubble of radius 2 cm. Calculate the increase in surface energy if the surface tension for soap is 25 dyne/cm. |
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Answer» Solution :Surface energy PER UNIT area is equal to surface tension. E = increase in surface area `xx` ST `=4pi(2^(2)-1^(2))xx2.5` =`4pixx3xx2.5` =`1.02xx10^(3)`erg |
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| 4. |
What is change in value of Reynolds number when fluid flow from broad tube to narrow tube ? [Tube is horizontal] |
| Answer» SOLUTION :When fluid flow BROAD TUBE to narroe tube it diameter decreases and Reynold number `R_(E)` decreases. | |
| 5. |
A system consists of two particles. At t = 0, one particle is at the origin, the other, which has a mass of 0.60kg, is on the y - axis at y = 80 m. At t = 0, the centre of mass of the system is on the y-axis at y = 24 m and has a velocity given by (6.0 m//s^(3))t^(2)hatj . (a) Find the total mass of the system, (b) Find the acceleration of the centre of mass at any time t, (c) Find the net external force acting on the system at t = 3.0 s. |
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| 6. |
The percentage error in surface area of a sphere is 6% then find the relative error in volume |
| Answer» Answer :B | |
| 7. |
The height of the Niagara falls is 50 metres. (1 cal = 4.2 J ). Assume its mechanical energy can be completed converted into heat energy |
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Answer» Heat energy GAINED by each gram of water is `49xx 10^(5)`cal |
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| 8. |
A massless conical flask filled with a liquid is kept on a table in a vacuum. The force exerted by the liquid on the base of the flask is W_1. The force exerted by the flask on the table is W_2. (i) W_1 = W_2 (ii)W_1 gt W_2 (iii) W_1 lt W_2 (iv)The force exerted by the liquid on the walls of the flask is (W_1 - W_2). . |
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Answer» (i),(IV) |
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| 9. |
Average velocity of the particle for the motion |
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Answer» 3.3 m/s `= (1)/(2) (6t + 8t) XX 10 - (1)/(2) (2t + 4T) xx 10` `= 70 t - 30 t = 40 t` `:.` Average velocity `= ("Displacement")/("Time") = (40t)/(12t) = 3.3 m//s` |
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| 10. |
A box is put on a scale which is adjusted to read zero, when the box is empty. A stream of pebbles is then poured into the box from a height h above its bottom at a rate of n pebbles. Each pebble has a mass m. If the pebbles collide with the box such that they immediately come to rest after collision, the scale reading at time t after the pebbles begin to fill the box is |
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Answer» `MN {SQRT((2gh))+"GT"}` |
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| 11. |
A body thrown vertically up with velocity u reaches the maximum height h after T seconds. Which of the following statements is true? |
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Answer» At a HEIGHT `(h)/(2)` from the ground its VELOCITY is `(U)/(2)` |
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| 12. |
The velocity v of a particle at time t is given by v = a t + (b)/(t + c), where a, b and c are constants. The dimensions of a, b and c are respectively |
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Answer» `LT^(-2), L and T` |
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| 13. |
A drop of water of diameter 0.2 cm is broken up into 27,000 droplets of equal volume. How much work will be done against surface tension in the process ? Surface tension of water =7xx10^(-2)"Nm"^(-1). |
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| 14. |
Derive an experession for the period of oscillation of a mass attached to a spring executing simple harmonic motion. Given that the period of oscillation depends on the mass m and the force constant k, where k is the force required to stretch the spring by unit length? |
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Answer» `[T]=[M^(x)][MT^(-2)]^(y)`. SIMPLIFYING `x=1//2, y=-1//2`. |
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| 15. |
A man standing on a road has tohold his umbrella at 30^(@) with the vertical to keep the rain away. He throws the umbrella and starts running at 10 kmph. He find that rain drops are hitting his head vertically. The speed of rain drops relative to the ground is |
| Answer» Answer :B | |
| 16. |
Water at 4^(@)C is filled in a vessel. What happens if it is (a) cooled, (b) heated, |
| Answer» SOLUTION :In both CASES it EXPANDS and OVERFLOWS, | |
| 17. |
Block A of mass m rests on the plank B of mass 3m which is free to slide on a frictionless horizontal surface. The coefficient of friction between the block and plank is 0.2. If a horizontal force of magnitude 2 mg is applied to the plank B, the acceleration of A relative to the plank and relative to the ground respectively, are : |
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Answer» `0,(G)/(2)` |
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| 18. |
Blood flows through a main artery of area of cross section 2cm^(2) with a speed of 0.25 ms^(92). If it branches into several capillaries of total area of cross section 0.4 m^(2) the average speed of blood through each capillary is |
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Answer» `0.25 MS^(-1)` |
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| 19. |
What do you meant by change of state of a substance ? |
| Answer» Solution :The TRANSITION of a substance from ONE state to another by heating or COOLING it is called change of state. | |
| 20. |
Define Astronomical unit, light year and parsec. |
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Answer» SOLUTION :Astronomical UNIT (AU) = Average distance between the Sun and the Earth is called astronomical unit. 1 AU = `1.496 xx 10^(11)` m Light Year : Distance travelled by light in vacuum in 1 year is called 1 light year. Speed of light in vacuum `C = 2.99 xx 10^(8) ms^(-1)` `:.`Distance travelled in 1 year =ct `=2.99xx10^(8)xx365xx24xx3600` `=9.46xx10^(15) m` Light year is used to measure distance between celestial objects. Parsec (pc): Distance at which average radius of earth.s orbit subtend angle of 1" (arc second) is called 1 parsec (pc).  From FIGURE `theta` (rad)= `(arc)/("radius")=(l)/(r)` `:.r=(l)/(theta)=(1AU)/(1..)` `(1AU=1.496xx10^(11)m)` `:.I..(1)/(60xx60)xx(pi)/(180)` (RADIAN) `:.r=(1.496xx10^(11))/(((1)/(60xx60)xx(pi)/(180)))` `:.r=3.08xx10^(16) m` 
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| 21. |
The distance of Pluto from sun is 40 times than the distance of earth from sun. If the mass of earth and Pluto is same, then find the ratio of gravitational force of sun on earth and Pluto. |
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Answer» SOLUTION :`IMPLIES F_(es) prop (m_em_s)/((r_(es))^2)` `F_(ps)prop(m_"p"m_s)/((r_(ps))^2)` `(F_(es))/(F_(ps))=(r_(ps))^2/((r_(es))^2) =((40x^(2))/x)^2` `= 1600 : 1 ` |
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| 22. |
A ray of light incidents on a refracting surface at 30^@ with the surface. If the angle of refraction is 45^@ refractive index of the medium is |
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Answer» `SQRT3` |
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| 23. |
The viscous drag on a spherical body moving with a speed v is proportional to |
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Answer» V |
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| 24. |
A car travelling at 108 km//hour has its speed reduced to 36 km//hourWhile travelling a distance of 200m . Its retardation and the time taken are |
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| 25. |
A particle is projected up from a point at an angle 'theta' with the horizontal direction. Which of the following graph represents the variation kinetic energy (K) with time (t) |
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| 26. |
A body is initially at rest . It undergoesone - dimensional motion with constant acceleration .The powerdelivered to it at time t is proportional to |
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Answer» `t^(1/2)` `P = (F)` (v) ` = (F) (F/m) t [ :. v = at = F/m t]` `=(F/m)^(2) MT` ` :. P = a^(2) mt ""` [ a and m are CONSTANT ] ` :. P prop t ` |
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| 27. |
A block weighing 5 kg is pressed against a verticalk wall by a normal force of 150 N the coefficient of friction along being 0.5 . Find the force required to cause the block to move (a) horizontally, (b) vertically upward, (c) vertically downwards. |
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| 28. |
In a system of units, if force (F), acceleration (a) and time (T) are taken as fundamental units then the dimensional formula of energy is ............... |
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Answer» `[FA^(2)T]` |
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| 29. |
A long thin string has a coat of water on it. The radius of the water cylinder is r. After some time it was found that the string had a series of equally spaced identical water drops on it. Find the minimum distance between two successive drops. |
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| 30. |
In a humanpyramid in a circus, the entire weightof the balancedgroup is supported by the legs of a performer who is lying on his back. The combined mass of all the persons performing the act, and the tables, planks etc. involved is 280 kg. The mass of the performer lying on his back at the bottom of the pyramid is 60 kg. Each thighbone (femur) of this performer has a length of 50 cm and an effective radius of 2.0 cm. Determine the amount by which each thighbone gets compressed under the extra load. |
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Answer» Solution :Total mass of all the PERFORMERS, tables plaques etc. = 280 kg Mass of the PERFORMER= 60 kg Mass supported by the legs of the performer at the bottom of the pyramid`=280-60=220kg` Weightof this supported mass `=220 kg WT. = 220xx9.8=2156 N`. Weight supported by each thighbone of the performer `=1//2(2156)=1078N`. The young.s modulus `Y=9.4xx10^(9)Nm^(-2)` (COMPRESSIVE) Length of each thighbone `L=0.5m` the radius of thighbone= 2.0 cm Thus the cross-sectional area of thighbone `A=pi xx (2xx10^(-2))^(2)m^(2)` `=1.26xx10^(-3)m^(2)`. The compression in each thighbone `DeltaL=[(FxxL)//(YxxA)]` `=[(1078xx0.5)//(9.4xx10^(9)xx1.26xx10^(-3))]` `=4.55xx10^(-5)m`. |
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| 31. |
A block of weight 100N is pushed by a force F on a horizontal rough plane moving with an acceleration 1 m//s^(2), when force is doubled its acceleration becomes 10m//s^(-2). The coefficient of friction is (g=10m//s^(-2)) |
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Answer» 0.4 |
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| 32. |
The mass and volume of a body and found to be 4 pm 0.03 kg and 5 pm 0.01 m^(3) respectively. Then find the maximum possible percentage error in density. |
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Answer» SOLUTION :Mass m = `4 pm 0.03` kg `(m + DELTAM)` Volume V = `5 pm 0.01 m^(3) (V + DeltaV)` Density = ? Error in mass = `(Deltam)/(m) = (0.03)/(4) xx 100 = 0.75%` Error in volume `= (DeltaV)/(V) = (0.01)/(5) xx 100 = 0.2%` Density = `("mass")/("volume")` Error in density = error in mass + error in volume = 0.75% + 0.2% = 0.95% |
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| 33. |
Assertion:Soap bubble is larger than a water drop.Reason: Surface tension of soap bubble is less than that of water.Choose the correct choice of the following choices. |
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Answer» Both assertion and REASON are TRUE and reason explains assertions correctly. |
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| 34. |
In an experiment with bar pendulum having four holes, the same time period is recorded when it is suspended at distances 12 cm, 24cm. 40 cm and 52 cm respectively from one end. The length of bar pendulum is |
| Answer» Answer :C | |
| 35. |
Find the difference between 'g' on pole and 'g' on equator due to rotation of earth. &p - Se = (g) - (g- R.02) Ep = R.02 |
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Answer» Solution :`IMPLIES g_p -g_e =(G) -(g-R_(e)omega^(2))` `g_(p) = R_(e)omega^(2)` |
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| 36. |
Define latent heat of fusion and latent of vapourisation. Explain the variation of temperature with heat (energy) for water at one atmosphere with a graph. |
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Answer» Solution :The amount of heat required to CHANGE a substance from solid state into LIQUID state at its melting point is called as latent of fusion of the solid and from liquid to vapour at its boiling point is called the latent of vapourisation. `(Q=mL).` Water boils at a constant temperature of `100^@ C` at SEA level and requires a minimum of heat equal to the latent heat of steam `(L_("steam")=2.26xx10^6 J kg^(-1) ).` The temperature of steam go beyond `100^@ C` and heat content beyond `2.26xx10^6 J kg^(-1))`. (Hence steam causes more heat INJURY than boiling water on the skin). 
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| 37. |
Describe the construction and working of venturimeter and obtain an equation for the volume of liquid flowing per second though a wider entry of the tube |
Answer» Solution : Venturimeter : This device is used to measure the rate of flow ( or say flow speed) of the incompressible fluid flowing through a PIPE. It works on the principle of Bernoulli.s theorem. It consists of two wider tubes A and A. (with cross sectional area A) connected by a narrow tube B ( with cross sectional area a). A manometer in the fonn of U-tube is also attached between the wide and narrow tubes. The manometer contains a liquid of density `. rho_m .` Let `P_1`be the pressure of the fluid at the wider region of the tube A. Let us assume that the fluid of density .`rho` . flows .from the pipe with speed `v_1`and into the narrow region, its .speed increases to `v_2` . According to the Bernoulli.s equation, this increase in speed is accompanied by a decrease in the fluid pressure `P_2`at the narrow region of the tube B. Therefore, the pressure difference between the tubes A and B is NOTED by measuring the height difference`(Delta P = P_1 + P_2)`between the surfaces of the manometer liquid. From the equation of CONTINUITY, we can say that `Av_1 = av_2`which means that ` v_2= A/a v_1` Using bernoulli.s equation, ` P_1 + rho (v_1^2)/(2) = P_2 + rho (v_2^2)/(2) = P_2 + rho 1/2 (A/a v_1)62` from the above equation , the pressure difference ` Delta P = P_1 - P_2= rho (v_1^2)/(2) (A^2 - a^2)/(a^2)` Thus , the speed of flow of liquid at the wide end of the tube A ` v_1^^2 = (2 (Delta P)a^2)/(rho(A^2 - a^2) ) rArr v_1= sqrt((2(Delta P)a^2)/(rho (A^2 - a^2) )` The volume of the liquid flowing out per SECOND is `V = A v_1 = A sqrt( (2 (Delta P )a^2)/(p (A^2 -a^2) ) )= a A sqrt( (2(Delta P))/(p(A^2 - a^2) ))` |
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| 38. |
If vecA = 2hat(i) -3hat(j) + 4hat(k) its components in yz plane and zx plane are respectively. |
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Answer» `SQRT(13) and 5` |
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| 39. |
If the period of oscillation changes from 2 sec to 1.5 sec, and the length of simple pendulum is 1m, then the change in length is |
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Answer» INCREASED by`(7)/(16)m` |
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| 40. |
A piece of stone thrown vertically upwards comes to rest momentarily at its maximum height. Is the stone in equilibrium at this position? |
| Answer» Solution :The stone though MOMENTARILY at REST at the maximum height is not equilibrium there. It has a DOWNWARD ACCELERATION due to the earth.s gravitational FORCE. | |
| 41. |
Consider the following two statements. A) If heat is added to a system,its temperature must increase B0) If positive work is done by a system in a thermodynamics process, its volume must increase |
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Answer» Both A and B are CORRECT |
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| 42. |
A small ball of mass m collides with a rough having co-efficient of friction mu at an angle theta with the normal to the wall. If aftercollision the ball moves with angle alpha with the normal to the wall and the coefficient of retitution is 'e' the find reflected velocity v of the ball just after the collision is V = (u)/(sin alpha)[sin theta - mu cos theta)(e+x)] where 'x' is |
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| 43. |
The temperatures T_1 and T_2of two heat reservoirs in the ideal Carnot engine are 1500^@ C and 500^@ C respectively. Which of these, increasing T_1 by 100^@ C or decreasing T_2 by 100^@ C, would result in a greater improvement in the efficiency of the engine ? |
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Answer» SOLUTION :As the EFFICIENCY of a heat engine is given by ` eta=11- (T_L )/( T_H)= (T_H - T_L)/( T_H)` so when `T_n`is INCREASED by `100^@ C,eta _1= ((1600 - 500))/(( 1600 +273)) = (1100 )/( 1873 ) = 59 % ` and when `T_L` is DECREASED by `100^@ C,eta_2 = ((1500- 400 ))/( 1500+ 273 ) = (1100)/( 1773 )= 62 % ` From Egns. (1) and (2), it is CLEAR that decreasing `T_L` results in greater improvement in the efficiency. |
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| 44. |
There are three distinct modes of heat transfer.The main mode of transmission of heat by which the sun heats the surface of the earth is : |
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Answer» conduction |
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| 45. |
Air streams horizontally across an aeroplane wing of area 3m^(2) weighing 250 kg. The air speed is 60 m/s and 45 m/s over the top surface and under the bottom surface respectively. What is the lift on the wing? (Density of air 1.293 g/l) |
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Answer» 3000 N |
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| 46. |
Arrange the following parameters for elasticity, Yield point (Y), limit of proportionality (P) range of Hooke's law (H) and Breaking stress (B) in the increasing order of stress |
| Answer» Answer :C | |
| 47. |
If the liquid used in a hydraulic press is replaced by a gas, then the press |
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Answer» continues to work as before |
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| 48. |
If in the above problem the block is replaced by a small spherical ball of radius r and the cup is fixed, what will be the period of oscillations of the ball? |
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| 49. |
The wavelength of maximum energy released during an atomic explosion was 2.93xx10^(-10) m. Given that Wein.s constant is 2.93xx10^(-3)m-K, the maximum temperature attained must be of the order of |
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Answer» `10^(-7)K` |
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