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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. |
The acceleration due to gravity g is plotted against the latitude phi of a place. Out of the following, the one that best represents the graph is |
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| 2. |
The value of the specific heat at constant pressure for hydrogen is 3.4 kcal kg^(-1) ""^(@)C^(-1).Determine C_(V) for hydrogen if J = 4.2 J/cal. Density at NTP is 8.9 x 10^(-5) kg/litre. [E.Q] |
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Answer» Solution :`C _(p) = 3.4 K cal ^(-1) kg ^(-1) ""^(@)C ^(-1) = 3.4 xx 10 ^(3) cal ^(-1) kg ^(-1) l ^(@)C ^(-1) = 3.4 xx 10 ^(3) xx 4.2 J kg ^(-1) K ^(-1).` `C _(v) = ? C _(v) = C _(p) -R ` We have to find r `r = (PV)/(T), P = 101325 NM ^(-2), T = 273K` `V = ( " Mass ")/("DENSITY") , ` mass = 1 kg Density `= 8.9 xx 10 ^(-5) (kg)/("litre") = (8.9 xx 10 ^(-5))/(10 ^(-3)) (kg)/( m ^(3)) = 8.9 xx 10 ^(-2) kg//m^(3)` `V = (1)/( 8.9 xx 10 ^(-2)) m ^(3)` `r = (PV)/(T) = ( 101325)/(273) xx (1)/(8.9 xx 10^(-2)) = 4170J kg ^(-1) K ^(-1)` `C _(V) = 14280 -4170 = 10110 J kg ^(-1) K ^(-1)` |
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| 3. |
A man floating on a raft in water flowing at 2 kmph observes a motor launch overtaking him at t=0. Then launch travels with the speed of 20kmph relative to still water . After travelling for a time of 1 hr, the launch turns back towards raft . How for from the original point of crossing do they meet and what is the total time elaped ? |
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Answer» Solution :Figure shows point A,B,C and D along bank A`rarr ` point of crossing for first time. B,D `rarr` positions of raft and BOAT when boat TURNS back .  C `rarr ` Positions of raft and boat during the second crossing Note : If we fix the observer on thebank, raft has a SPEED of kph, boat has a speed of `20+2=22`kph for distance AD and `20-2=18 kph` for distance DC. It is possible to solve w.r.t. bank . However the solution is quite cumbersome. Fix the observer on raft W.r.t. raft , the boat has same velocity upstream as well as DOWNSTREAM. Hence, if the boat travels for 1 hr, while moving away from raft, it travels the same time while approaching the raft, `:. ` time between two crossings `=t.=2h`. We now find the distance traveled by raft in `2 hr =2xx2=4km`. |
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| 4. |
A particle with radius R is moving in a circular path with constant speed. The time period of the particle is T. Calculate the time for the following aftert=T6. What is the average velocity of the particle |
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Answer» 3R/T |
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| 5. |
The efficiency of a carnot engine is 40%, whose sink is at a temperature of 300 K. By how much should be temperature of the source be increased be get an efficiency of 60% ? |
| Answer» Solution :`0.4 =1 - (300 //T_(1)) , T _(1) = 500 K, 0.6 = 1 - (300 // T _(1)) , T_(1) = 750K,` INCREASE by 250 K | |
| 6. |
Define unit of power |
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| 7. |
The extension of a wire by application of a load is 0.3 cm. The extension in a wire of same material, but of double the length and half the radius of cross-section, by the same load will be, in cm |
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Answer» 0.3 |
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| 8. |
If radius of the earth is reduced by n times without changing its mass, then what will be the magnitude of g'_eat the surface of earth? |
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Answer» SOLUTION :`implies g_(E) = n^(2) g_(e)` because on the surface `g_e =(GM_e)/(R_e^2)` After shrinks radius `R._(e) =R_(e)/n` After shrinks`g_(e) =(GM_e)/R_e^2` `:. g_e/(G._e) = (g._e)^2/(R_E^2)` but `R_e/n` ` = R_e^2/n^2 xx1/R_e` `g_e/(g._e)=1/n^2` `:. g_e=n^2 .g_e` |
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| 9. |
A projectile is given an initial velocity of (hati +2hatj)m/s, where hatjis along the ground and s is along the velocity. If g = 10 m//s^1, the equation of its trajectory is |
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Answer» `y= x -5 x^2` |
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| 10. |
The handle of a door is at a distance 40 cm from axis of rotation. If a force 5Nis applied on the handle in a direction 30^(@) with plane of door, then the torque is |
| Answer» ANSWER :B | |
| 11. |
The length of a metal wire is l when the tension in it is .F. and .xl. when the tension is .yF.. Then the natural length of the wire is |
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Answer» `((x-y)L)/(x-1)` |
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| 12. |
Particle A is released from a point P on a smooth inlined plane inclined at an angle alpha with the horizontal. At the same instant another particle B is projected with initial velocity U making an angle betawith the horizontal. Both the particles meet again on the niclined plane. |
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Answer» Velocity along the INCLINED PLANE is same for both particles always |
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| 13. |
Differentiate between isothermal and adiabatic process. |
Answer» SOLUTION :
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| 14. |
Why do people prefer to give a layer sand or foam insulation on ceiling made up of concrete ? |
| Answer» Solution :The thermal CONDUCTIVITY of concrete though MUCH smaller than that of metal is still not SMALL enough. Therefore, people usually prefer to give a LAYER of sand or foam insulation on the ceiling so that heat transfer is prohibited and keeps the room cooler. | |
| 15. |
A cubical block of side 4 cm is moving with 4 m/s on a smooth horizontal plane as shown. It hits a ridge at point O. The angular speed of block after it hits O is "15Y rads"^(-1), then value of Y is _____ . |
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| 16. |
A bullet fired at an angle of 30^(@) with the horizontal hits the ground 3.0 km away. By adjusting its angle of projection, can one hope to hit a target 5.0 km away ? Assume the muzzle speed to be fixed, and neglect air resistance. |
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Answer» Solution :We are given that angle of projection with the horizontal, `theta = 30^(@)`, horizontal range R = 3km. As `R = (v_(0)^(2) sin 2 theta)/(g) , 3 = (v_(0)^(2) sin 60^(@))/(g) = (v_(0)^(2))/(g) xx (sqrt(3))/(2)` or `(v_(0)^(2))/(g) = 2sqrt(3)km` SINCE the muzzle speed `(v_(0))` is fixed, `R_("max") = (v_(0)^(2))/(g) = 2sqrt(3) = 2 xx 1.732 = 3.464 km` Obviously, it is not POSSIBLE to hit the target 5km away. |
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| 17. |
A particle has an initial velocity 3hat(i) + 4hat(j) and an acceleration of 0.4hat(i) + 0.3hat(j). Its speed after 10s is |
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Answer» 10 UNITS |
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| 18. |
Which concepts are needed for description of a periodic motion? |
| Answer» Solution :For description of periodic motion basic CONCEPTS like period, frequency, displacement, AMPLITUDE and PHASE are NEEDED. | |
| 19. |
A heavy block 'B' is sliding with constant velocity u on a horizontal table. The width of the block is L. There is an insect A at a distance d from the block as shown in the figure. The insect wants to cross to the opposite side of the table. It begins to crawl at a constant velocity v at the instant shown in the figure. Find the least value of v for which the insect can cross to the other side without getting hit by the block. |
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| 20. |
If the ratio of the amplitudes of two waves is 4 : 3 then the ratio of maximum and minimum intensities is ……….. . |
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Answer» `16 : 9` |
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| 21. |
The system shown in the figure is in equilibrium at rest. The spring and string are massless Now the string is cut. Find the acceleration of the blocks just after the string is cut. |
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Answer» Solution :Under equilibrium of mass m T= mg. Now the string is CUT, Therefore T= mg force is DECREASED on mass m UPWARDS and downwards on mass 2M. `:.` Acceleration of `m=(mg)/(m)=G` Acceleration of `2m=(3mg-2mg)/(2m)=(g)/(2)` |
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| 22. |
An ideal spring of spring constant k, is suspended from the ceiling of a room and a block of mass M is fastened to its lower end. If the block is releasedwhen the spring is un-stretched , then the maximum extension in the spring is |
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Answer» `4(Mg)/(K)` |
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| 23. |
An ideal gas with pressure P, volume V and temperature T is expanded isothermally to a volume 2V and a final pressure P_(1). The same gas is expanded adiabatically to a volume 2V, the final final pressure is P_(A). In terms of the ratio of the two specific heats for the gas gamma, the ratio P_(I)//P_(A) is |
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Answer» <P>`2^(gamma - 1)` `:. PV = P_(I) 2V` or `P_(I) = (P)/(2)` …(i) For an adiabatic process, `PV^(gamma)` = constant `:. PV^(gamma) = P_(A) (2V)^(gamma)` or `P_(A) = (P)/(2^(gamma))` …(ii) Divide (i) by (ii), we get `(P_(I))/(P_(A)) = (2^(gamma))/(2) = 2^(gamma - 1)` |
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| 24. |
A splash is heard 3.91 after a stone is dropped into a well of 67.6 m deep. The speed of sound in air is |
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Answer» `346m//s` |
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| 25. |
An infinite number of bodies, each of mass 2 kg, are situated on at distance 1m, 2m, 4m, 8m from the origin. What will be the resultant gravitational potential due to this system at the origin. |
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Answer» SOLUTION :Gravitationalpotentialat the origin is ` V = - G [ m/(r_(1)) +m/(r_(2)) +m/(r_(3)) +m/(r_(4)) + ...... ] = - G [ 2/1+2/5 +2/4 +2/8 +.......] ` ` - 2G [1+1/2 +1/(2^(2)) + 1/(3^(2))+ ......]= - 2G [ 1/(1-(1/2))] ` `V = - 4G` |
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| 26. |
A chain of mass m and length L is held vertical such that its lower end just touches the floor. It is released from rest. Find the force exerted by the chain on the table when upper end is about to hit the floor. |
| Answer» Answer :B | |
| 27. |
A particle is projected vertically upwards with a velocity of 20m/sec. Find the time at which distance travelled is twice the displacement |
| Answer» Answer :A | |
| 28. |
A clinical thermometer is usually much shorter than a laboratory thermometer, because |
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Answer» only a limited range of TEMPERATURE is required |
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| 29. |
n indentical blocks each of massm are connected by means less strings and a pulling force F is applied on the first block. Find block . Find the tension in the string connecting k^("th") and ) (k+1)^("th") blocks. If another pulling force F is applied on the least block, find the tension in the same . String. |
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Answer» `[F(N-k)//n]N,F` |
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| 30. |
In case of forced vibration, the resonance wave becomes very sharp when the |
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Answer» Restoring force is SMALL |
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| 31. |
Two blocks of masses 10 kg and 4kg are connected by a spring of negligible mass and placed on a frictionless horizontal surface. An impulse gives a velocity of 14ms^(-1) to the heavier block in the direction of the lighter block. The velocity of the centre of mass is |
| Answer» Answer :C | |
| 32. |
The ratio of the acceleration due to gravity at the bottom of a deep mine and that on the surface of the earth is 978"/"980. Find the depth of the mine if the density of the earth is uniform throughout and the radius of the earth is 6300 km. |
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Answer» `12.86 KM` |
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| 33. |
In above problem identify incorrect sign of average velocity for an interval |
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Answer» `1 rarr +` |
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| 34. |
Three masses 0.1 kg, 0.3 kg and 0.4 kg are suspended at the end of the spring. When the 0.4 kg is removed, the system oscillates with a period of 2 sec. When 0.3 kg mass is also removed, the system will oscillates with a period |
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Answer» 1 sec |
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| 35. |
A rocket explodes in mid air. How does this affect its total momentum? |
| Answer» SOLUTION :It does not change TOTAL MOMENTUM. Because no external force ACTS on the ROCKET. | |
| 36. |
A litre of hydrogen at 127^(@)C and 10^(6)dynecm^(-2) pressure expands isothermally until its volume is doubled and then adiabatically until its volume is redoubled. Find the final pressure of the gas. Given gamma = 1.4. |
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| 37. |
The mass of a planet is (1)/25^(th)of the mass of the w earth. The distance between the planet and the earth is 6x 108m. At what distance from the earth, the gravity becomes zero |
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Answer» `1XX10^(8)m` |
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| 38. |
In a double acting steam engine, the average pressure in 90Ncm^(-2), the area of the piston is 7.46 cm^(2), the length of the strokes is 1 meter and the number of revolution per second is 5. find the horse power of the engine. |
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| 39. |
One mole of an ideal gas undergoes a process such that P prop (1)/(T). The molar heat capacity of this process is 4R. |
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Answer» The work done by the GAS is `2R Delta T` |
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| 40. |
Two light verticle springs 1 and 2 of stiffness K and 2K are connected by a 1 light horizontal rod. A bead of chewing gum of mass 'm' is placed gently at the mid point of the rod and lowered slowly. The ratio of magnitude of work done by the external agent to that by gravity in lowering the bead till it remains at rest is |
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Answer» `1:1` |
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| 41. |
Two particle which are initially at rest, move towards each other under the action of their internal alteration. If there speeds are v and 2v at any instant, then the speed of centre of mass of the system will be………. |
| Answer» Solution :Hence no external force acting on a system of particle and initially its centre of MASS is at rest will be remain at rest in FINAL position and the speed of centre of mass is zero. | |
| 42. |
Passage - I : A particle is moving in a circular path of radius a, with constant velocity v as shown in the figure. The center of circle is marked by 'C' the particle is at P. The angular momentum from the origin O can be written as : |
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Answer» `"MVA "(1+COS2THETA)` |
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| 43. |
Passage - I : A particle is moving in a circular path of radius a, with constant velocity v as shown in the figure. The center of circle is marked by 'C' the particle is at P. Angular momentum with respect to C can be written as |
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Answer» `"MV"` |
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| 44. |
The maximum wavelength of radiations emitted at 900 K is4mu m . What will be the maximum wavelength of radiations emitted at 1200 K |
| Answer» Answer :A | |
| 45. |
Find the terminal velocity of solid sphere of radius 0.1 m moving in air in vertically downward direction. (eta=1.8xx10^(-5)Ns7m^(2) density of sphere = 1000kg//m ^(3)and g=10m//s^(2)) |
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Answer» 2m/s |
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| 46. |
(A) : Generally the path of a projectile from the earth is parabolic but it is elliptical for projectile going to a very great height. ( R) : Up to ordinary height the projectile moves under a uniform gravitational force, but for a great heights, projectile moves under a variable force. |
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Answer» Both (A) and ( R) are ture and ( R) is the correct EXPLANATION of (A) |
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| 47. |
Explain conservation of linear momentum by suitable example. |
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Answer» SOLUTION :Lawofconservationof linearmomentumcan be obtainedby usingnewtonsecondlaw andthirdlaw ofmotionwhenbulletis firedfromgunbulletmovesinforwarddirectionand gunmoves L in backwarddirection. Initiallyboth areat resthencechangeinmomentum of bothequalto finalmoementum . Letfinalmomentumof gun be `VEC( p)_(g)`and bullet be`vec(p)_(b )` then thustotallinearmomentumof sytemis conserved. Thusforisolatedsystemtotalfinalmomentumis l equalto totalinitialmomentum LAWOF conservationof linearmomentumisuniversaland fundamental . itequallyholdtrueof systemof smallerparticleslikeelectronprotonneutron as well as largersystemmadeup of electronprotonneutron. |
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| 48. |
what is the SI unit of pressure? Drive a mathematical expression for excess pressure inside a liquid drop. |
| Answer» SOLUTION :The SI UNIT of PRESSURE is PASCAL. | |
| 49. |
A simple pendulum of length l and having a bob of mass M is suspended in a car. The car is moving on a circular track of radius R with a uniform speed V. If the pendulum makes small oscillation in a radial direction about its equilibrium position, what will be its time period? |
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Answer» Solution :The pendulum bob is subject to two distinct ACCELERATIONS: (i) the acceleration DUE to gravity, `vecg`, acting down-wards, (ii) the centripetal acceleration, `veca=v^(2)/2`, acting in a horizontal direction FIG. So, the effective, or relative, acceleration due to gravity on the pendulum bob is, `g^(vecr)=vecg-veca=vecg+(vec(-a))`  Its magnitude, from Fig., is `g.=sqrt(g^(2)+V^(4)/R^(2))`. Then, the time period of the pendulum becomes, `T.=2pisqrt(L/(g.))=(2pisqrtl)/((g^(2)+V^(4)/R^(2))^(1//4))` |
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