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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. |
When a fast moving bus suddenly stops, the passenger is thrown forward because of |
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Answer» INERTIA of rest |
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| 2. |
If refractivemeasure of water are 1.32,1.33,1.34, 1.35 and 1.36 then find of absolute error, relative error and percentage error. |
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Answer» SOLUTION :ABSOLUTE ERROR `=0.012` RELATIVE error=0.009, PERCENTAGE error `=0.9%` |
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| 3. |
Explain propagation of errors in the diffedence of two quantities and also in the divison of two quantities. |
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Answer» Solution :Error in the differnce of two quantities: Let `DeltaA` and `DeltaB` be the absolute errors in the two quantities A and B respectgively. Then, Measured value of `A=A+-DeltaA` Measured value of `B=B+-DeltaB` Consider the difference `Z=A-B` The error `DELTAZ` in Z is then GIVEN by `Z+-DeltaZ=(A+-DeltaA)-(B+-DeltaB)` `=(A-B)+-(DeltaA+DeltaB)` `=Z+-(DeltaA+DeltaB)` (or) `DeltaZ=DeltaA+DeltaB` The maximum error in difference of two quantities is equal to the SUM of the absolute errors in the individual quantities. Error in the division or quotient of two quantities. Let `DeltaA` and `DeltaB`be the absolute erros in the two quantities A and B respectively. Consider the quotient `Z=A/B` The error `DeltaZ` in Z is given by `Z+-Z=(A+-DeltA)/(B+-DeltaB)=(A(1+-(DeltaA)/A))/(B(1+1(DeltaB)/B))` `=A/B(1+-(DeltaA)/A)(1+-(Delta+-(DeltaB)/B)^(-1)` or `Z+-DeltaZ=Z(1+-(DeltaA)/A)(1+-(DeltaB)/B)` [using `(1+x)^(n)~~1+nx`, when `x lt lt 1`] DIVIDING both sides by Z, we GET `1+-(DeltaZ)/Z=(1+-(DeltaA)/A)(1+-(DeltaB)/B)` `=1+-(DeltaA)/A+-(DeltaB)/B+-(DeltaA)/A . (DeltaB)/B` As the terms `DeltaA//A` and `DeltaB//B` are small, their product term can be neglected. The maximum fractional error in Z is given by `(DeltaZ)/Z=((DeltaA)/A+(DeltaB)/B)` The maximum fractional error in the quotient of two quantities is equal to the sum of their individual fractional errors. |
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| 4. |
The horizontal and vertical components of a force re 8 N and 15 N respectively. The force is |
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Answer» 23 N |
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| 5. |
A particle of mass m moving with velocity v strikes a particle of mass 2m at rest and sticks to it. The speed of the combined mass is |
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Answer» `v/2` `MV=(m+2m)v^(1)` `v_(1)(mv)/(3m)=v/3` |
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| 6. |
Explain the classification of longitudinal stress? |
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Answer» Solution :Longitudinal stress can be classified into TWO TYPES, tensile stress and compressive stress. Tensile stress : Internal force on the two sides of `Delta A` may pull each other, i.e., it is stretched by equal and oppositeforces. Then , the longitudinal stress is called tensile stress. Compressive stress : When forces acting on the two sides of `Delta A` push each other, `DELTAA` is pushed by equal and opposite forces at the two ENDS. In this case, `DeltaA` is said to beunder COMPRESSION. then , the longitudinalstress is called compressive stress. |
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| 7. |
A solid sphere is rotating freely about its symmetry axis in free space. Ther adius of the sphere is increased keeping its mass same. Which of the following physical quantities would remain constant for the sphere? |
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Answer» ANGULAR momentum |
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| 8. |
When a man stands on a moving escalator he goes up in 50 sec. and when he walks up the moving escalator he goes up in 30 sec. Then the man walks up the stationary escalator in a time of ………… sec |
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Answer» 60 |
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| 9. |
A force of 8 N is resolved into two components right angles to each other. One of these is 4 N. The other is |
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Answer» 6.9N |
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| 10. |
Two rods one of copper, theother of brass are joinedend . Boththe rodsare similar in length and crosssection . The freeends of copperand brass are at 0^(@)Cand 100^(@)Crespectively. Calculatethe temperature of thejunction in equilibrium if thermal conductivityof copperis 4 timesthat of brass . |
| Answer» SOLUTION :`20^(@)C` | |
| 11. |
An astronaut accidentally gets separated out of his small spaceship accelerating in inter stellar space at a constant rate of 100 m s^(-2) .What is the acceleration of the astronaut the instant after he is outside the spaceship ? (Assume that there are no nearby stars to exert gravitational force on him.) |
| Answer» Solution :Since there are no nearby stars to exert GRAVITATIONAL FORCE on him and the small spaceship exerts negligible gravitational attraction on him, the net force acting on the astronaut, once he is out of the spaceship, is ZERO. By the first law of MOTION the acceleration of the astronaut is zero. | |
| 12. |
State in the following cases, whether the motion is one ,two (or) three dimensional .A planet revolving around its star . |
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Answer» |
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| 13. |
Calculate the external work done by the system in kCal, when 40 k Cal of theat is supplied to the system, 8400 J of internal work is done. |
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Answer» Solution :Heat SUPPLIED to the SYSTEM at constant pressure = change in internal energy + External work DONE. The change in internal energy = Internal work done `=8400 J = (8400)/(4200) kCal = 2kCal` `:.40kCal=2kCal+` External work done. The external work done `=40-2=38`kCal |
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| 14. |
The fundamental frequency of a closed organ pipe is equal to the first overtone of an open organ pipe. If the length of the open pipe is 60 cm, What is the length of the closed pipe? |
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Answer» Solution :Fundamental frequency of a closed organ PIPE, `v_(1)=(v)/(4L)` Fundamental frequency of an open organ pipe, `v'_(1)=(v)/(2L')` Frequency of first overtone of open organ pipe, `v'_(2)=2v'_(1)(v)/(2L')` GIVEN `v'=v'_(2)` `:.(v)/(4L)=(v)/(L')` (or) `L=(L)/(4)=(60)/(4)=15CM`. |
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| 15. |
A rocket in space is being propelled by the ejection of a gas. What is the velocity of the centre of mass of the rocket-fuel system? |
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Answer» |
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| 16. |
A particle executing simple harmonic motion has a kinetic energy K_(o)cos^(2)omegat. The maximum values of the potential energy and the total energy are, respectively…………. |
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Answer» `k_(0)//2andk_(0)` |
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| 17. |
Find the ratio of accelerations of two objects whose vto t graphs make angles 30^(@) and 45^(@) with axis of time. |
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Answer» SOLUTION :SLOPE of `v to t` graph `= tan theta` Slope of `v to t ` graph = acceleration `THEREFORE` Acceleration` = tan theta` `therefore (a _(1))/(a _(2)) = ( tan theta _(1))/( tan theta_(2))=(tan 30^(@))/(tan 45^(@))` `therefore (a _(1))/( a _(2)) = ((1)/( SQRT3))/( 1) = (1)/( sqrt3)` |
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| 18. |
Where do we use indirect methods to measure distance ? |
| Answer» Solution :To measure the very SMALL and the very LARGE distances, INDIRECT METHODS have to be devised and USED. | |
| 19. |
"The magnitude of average velocity is equal to average speed". This statement is not always correct and not always incorrect. Explain with example, |
Answer» Solution : Supose, a car taken 18 s to move from O (0) to P (360. Noe in next 6s, it returns from P to Q (240) then by calculating average velocity and average speed the answer of this QUESTION can be explained. For motion for O to P, Average speed `= (OP)/(t _(1)) = (+ 360)/(18) = 20 ms ^(-1)` Aberage velocity `= ("Position of P-Position of Q")/(t _(1))` `= (360-0)/(18)= (360)/(18)=20 ms ^(-1)` Here, both are equal, For motion from P to Q, Avewrage speed `= (OP +PQ)(t _(2)) -= (360)/(t_(1) + 6)` `[ because PQ =360 - 240 = 120]` ` = (480 )/(18 + 6) = (480)/(24) = 20 ms ^(-1)` Average velocity `= (Position Q-Position Of O")/(t _(2))` `= (240)/(24)= 10 ms ^(-1)` Here, both are not equal . |
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| 20. |
A circular disc of radius R and thickness (R)/(6) has moment of inertia about an axis passing through its centre and perpendicular to its plane. It is melted and recasted into a solid sphere. The moment of inertia of the sphere about its diameter as axis of rotation is |
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Answer» 1 |
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| 21. |
2 moles of a monoatomic gas are expanded to double its initial volume, through a processP/V = constant. If its initial temperature is 300 K, then which of the following is not true. |
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Answer» `Delta T = 900 K` |
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| 22. |
An elastic metal rod will change its length when ita) falls vertically under its weight b) is pulled along its length by a force actingat one end c) rotates about an axis at one end d) slides on a rough surface |
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Answer» only a, B are TRUE |
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| 23. |
A point moves in xy-plane according to equation x=a t, y = a t (1-bt)where a and b are positive constants and t is time.The instant at which veolcity vector is at pi//4with acceleration vector is given by: |
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Answer» `1//a` |
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| 24. |
Is evaporation of water a reversible process ? |
| Answer» SOLUTION :No, it is an irrvrsible PROCESS. | |
| 25. |
The rectangular surface of area 8"cm "xx4" cm" of a black body at a temperature of 127^(0)C emits energy at rate of E per second. If the legth and breadth are reduced to half of its initial value and the temperature is raised to 327^(0)C, the rate of emission of energy will be |
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Answer» `((3E)/(8))` |
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| 26. |
Why do internal forces in a system do not effect the velocity of a system? |
| Answer» SOLUTION :The internal forces in a system occur in EQUAL and opposite PAIRS and HENCE the contribution of the sum of forces is zero. | |
| 27. |
A uniform ladder of mass 10kg leans against a smooth vertical wall making an angle 53^(@) with it. The other end rests on a rough horizontal floor. Find the normal force and the frictional force that the floor exerts on the ladder. |
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Answer» Solution :The ladder is in equilibrium. `:.N_(1)=f` and `N_(2)=W` TAKING TORQUE about .B. `N_(1)(AO)=W(CB)`, or `N_(1)(AB)cos53=W((AB)/(2))sin53` or `N_(i)=(2)/(3)W` and `N_(2)=W=10xx9.8=98N`. The frictional force is `f=N_(1)=(2)/(3)W=65N` 
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| 28. |
A shell fired such that it hits a target at a distance 'b' and having height 'h' The minimum velocity with which it strikes the target |
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Answer» `SQRT(2gh)` |
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| 29. |
The work done by gravity in lifting a body to a certain height depends upon |
| Answer» Answer :D | |
| 30. |
A double stage rocket has an initial mass M_(1). Gas is exhausted from the rocket at a constant rate of dm/dt and with an exhaust velocity u relative to the rocket. When the mass of the rocket reaches the value 'mu' the first state of mass m is disengaged from the rocket then the rocket continues the second stage at the same rate (dm/dt) and exhaust velocity (u) as in the first stage unit it reaches a mass M_(f). If gravity is neglected and the rocket has started from rest, the velocity of the rocket at the end of first stage is |
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Answer» `U LIN ((m_(i))/(MU))` |
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| 31. |
What furnishes the centripetal acceleration for the earth to go round the sun ? |
| Answer» SOLUTION :The GRAVITATIONAL PULL of the SUM on the EARTH . | |
| 32. |
A particle of mass m moving with velocity 2v collides with another particle of mass 3 m moving with velocity v in the same direction. If it is perfect inelastic collision, the loss of K.E. of the system is |
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Answer» `(3)/(8)MV^(2)` |
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| 33. |
A particle of mass M is moving in a straight line uniform speed v parallel to x-axis X-Y plane at a height 'h' from the X-axis. Its angular momentum about the origin is |
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Answer» Zero |
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| 34. |
Tangential acceleration on a bob of a simple pendulum of mass 100gm when it amplitude is 1^(@) is |
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Answer» `0.017 m//sec^(2)` |
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| 35. |
A balloon starting from rest moves vertically upwards with an acceleration (g//8) ms^(-2). If a stone falls from it after 8 seconds from the start, find the time taken by the stone to reach the ground. |
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Answer» |
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| 36. |
An aeroplane flies along a straight path A to B and returns back again. The distance between A and B is 1 and the aeroplane maintains the constant speed v. There is a steady wind with a speed u at an angle thetawith line AB. Determine the expression for the total time of the trip. |
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Answer» Solution :A to B Velocity of plane along` AB =v COS alpha-ucos THETA`, and for no - drift from line . AB: `v sin alpha = usintheta RARR sin alpha (u sin theta)/v` time TAKEN from A to B `t_(AB)=l/(v COSALPHA - u cos theta)`  B to A velocity of plane along BA=`v cos alpha +u cos theta` and for no drift from line AB: `v sin alpha = usin theta rArr sin alpha (usin theta)/v` totaltime taken`t_(AB)+t_(BA)=(2vl cos alpha)/(v^(2) cos^(2) alpha-u^(2) cos^(2) theta)= 2vlsqrt(1-(u^(2)sin^(2)theta)/v^(2))/(v^(2)-u^(2))` |
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| 37. |
When a planet moves around the sun a) Its angular momentum remains constant b) its moves faster when it is near to the sun c) its total energy increases when it goes near to the sun d) its potential energy decreases when it goes near to the sun |
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Answer» only a&B are true |
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| 38. |
If solar constant is equal to 2 cal "(minute)"^(-1) cm^(-2), its value in S.I. system is |
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Answer» `1400 WM^(-2)` |
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| 39. |
A cylinderis made up of twocoaxiallayers,one of radiusR and the outerportions are respectivelymade up of substance of thermalconductivities K and2K . Dterminethe effective thermalconductivitybetween the flatends of the cylinder . |
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Answer» SOLUTION :Here `A_(1) = piR^(2) , K_(1) = K and A_(2) = 4piR^(2) - piR^(2) = 3piR^(2) , K_(2) = 2K` Usingthe expression for the effectivethermal CONDUCTIVITY`K_(eff)` , forslabs in PARALLEL , `K_(eff) = (A_(1)K_(1) + A_(2)K_(2))/(A_(1) + K_(2)) = (piR^(2) (K) + 3piR^(2) (2K))/(piR^(2) + 3piR^(2)) = (7K)/(4)` . |
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| 40. |
A pan with certain weight is attached to a spring. The period of vertical oscillation is found to be 0.5 sec. If some weight is added in the pan, the time period becomes 0.6 sec. The additional distance through which the spring stretches due to additional load is |
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Answer» `11/400 m` |
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| 41. |
A block of mass m is stationary with respect to a rough wedge as shown in figure. The system travels for time t with acceleration a (m=1 kg theta=30^(@),a=2m//s^(2),t=4s,g=10m//s^(2)) |
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Answer» |
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| 42. |
Two discs of moment of inertia I_(1) and I_(2) are rotating separately with angular velocities omega_(1) and omega_(2) respectively about perpendicular axis passing through their centres. If these two rotating discs are connected coaxially then the rotational kinetic energy of the composite system will be |
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Answer» `(I_(1)omega_(1)+I_(2)omega_(2))/(2(I_(1)+I_(2)))` |
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| 43. |
The apparent weight of a freely falling body is |
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Answer» ZERO |
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| 44. |
A material has poissons ratio 0.5. If a uniform rod of it suffers a longitudinal strain of 2xx 10^(-3) , then the percentage increase in its volume is |
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Answer» 0.6 |
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| 45. |
If a body is rotating, is it necessarily being acted by an external torque? |
| Answer» SOLUTION :No, TORQUE is REQUIRED only for ANGULAR ACCELERATION. | |
| 46. |
If a body loses half of its velocity on penetrating 3 cm in a wooden block, then how much will it penetrate more before coming to rest ? |
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Answer» |
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| 47. |
A force of 147 N is required to just slide a sledgeweighing 500 N over a surface of ice., Calculate the coefficient the coefficient of friction between the surface of contact of the sledge and the ice. |
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Answer» `0.472` |
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| 48. |
A point charge q is placed at the centre of a cubical box. Find the (a) total flux through the box. (b) through each face of the box |
| Answer» SOLUTION :`(a)Q/in_0,(B)q/(6in_0)` | |
| 49. |
Explain the types of motion with example |
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Answer» Solution :(a) Linear motion: An OBJECT is said to be in linear motion of it moves in a straight line. Examples: An athlete running on a straight track A particle falling vertically downwards to the Earth. (b)Circular motion: Circular motion is defined as a motion described by an obiet traversing a circular path Examples: The whirling motion of a stone attached to a string. The motion of a satellite around the Earth. These two circular MOTIONS are shown in figure.  (c) Rotational motion: If any object moves in a rotational motion about an axis, the motio is called .rotation. During rotation EVERY point in the object transverses a circular path about an axis. (except the points located on the axis). Examples: otation of a disc about an axis through its CENTER Spinning of the Earth about its own axis. These two rotational motions are shown in figure.  (d) Vibratory motion: If an object or particle executes a to and fro motion about a fixed point, it is said to be in vibratory motion. This is sometimes ALSO called oscillatory motion. Examples Vibration of a string on a guitar Movement of a swing These motions are shown in figure  Other types of motion like elliptical motion and helical motion are also possible. |
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