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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 block of mass 5 kg is kept on a horizontal floor having coefficient of friction 0.09. Two mutually perpendicular horizontal forces of 3 N and 4 N this block. The accelation of the block is ( take, g=10 ms^(-2)) |
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Answer» zero Maximum friction `f_("max")=mu mg` Since `F GT f_("max")` block will MOVE with an acceleration, `a=(F-f_("max"))/(m)` `=(5-4.5)/(5)=0.1 ms^(-2)` |
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| 2. |
What is level of wear and tear for vehicle moving on banked curved road with optimum speed ? |
| Answer» SOLUTION :MINIMUM | |
| 3. |
A spaceship is stationed on Mars. How much energy must be expended on the spaceship to launch it out of the solar system ? Mass of the space ship = 1000 kg, mass of the sun = 2 xx 10^(30) kg , mass of mars = 6.4 xx 10^(23) kg, radius of mars = 3395 Km: radius of the orbit of mars = 2.28 xx 10^(8)km ,G = 6.67 xx 10^(-11) N m^(2) kg^(-2). |
| Answer» Solution :`3 xx 10^(11)` J | |
| 4. |
The weight of a balloon is W_(1) when empty and W_(2) when filled with air. Both are weighed in air by the same sensitive spring balance and under identical conditions. |
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Answer» `W_(1)ltW_(2)` as the weight of air in the balloon is offset by the force of buoyancy on it. |
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| 5. |
Three point masses m_(1) , m_(2), m_(3) are located at the vertices of an equilateral triangle of length a. The moment of inertia of systein about an axis along the altitude of the triangle passing through m_(1) is |
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Answer» `(m_(2) + m_(3)) (a^2)/(4)` The moment of inertia of the system about the given axis is `I = m_1 XX 0^2 + m_(2) ((a)/(2))^(2) + m_(3) ((a)/(2))^(2) = (m_(2) + m_(3)) (a^(2))/(4)` 
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| 6. |
In which of the following pairs of temperature scales, the size of a degree is identical ? A) Mercury scale and ideal gas scale B) Celsius scale and mercury scale C) Celsius scale and ideal gas scale D) Ideal gas scale and absolute scale |
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Answer» A & B |
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| 7. |
What is the moment of a couple ? State any three characteristics of a couple . Give any one illustration for a couple. |
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Answer» Solution :The PRODUCT of magnitude of any one force and arm of the couple is known as moment of a couple. Characteristics : (1) Moment of a couple does not depend on the position of the point about which the body rotates. (ii) A couple ALWAYS produces a ROTATORY motion of the body. (3) A single force cannot balance or neutralise a couple. A couple is required to balance a couple, acting on a body. (4) If the restoring couple balances the deflecting couple, then the body is in a STATE of rotatory equilibrium. Illustration of a couple (1) openings or closing of a lid of a threaded neck of a bottle (2) The rotation of a freely suspended magnetic needle experience a couple due to Earth's magnetic FIELD. |
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| 8. |
A boat which has a speed of 5 km/hr in still water crosses a river of width 1 km along the shortest possible path in 15 minutes. The velocity of the river water in km/hr is |
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Answer» Solution :Resultant VELOCITY = `(1km)/((15//60)h) = 4 km//h` If v is velocity of RIVER, then `v^(2)+4^(2) = 5^(2) rArr v = sqrt(25-16) = 3 km//h` |
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| 9. |
The position of a particle at time t is given by the equation x(t) = V_(0)/A (1-e^(At)) V_(0) = constant and A > 0 Dimensions of V_(0) and A respectively are |
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Answer» `M^(0) LT^(0) and T^(-1)` |
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| 10. |
On a planet, body is let fall freely from a height 8m reaches the ground in 2 sec. If thelength of a simple pendulum is 1 m on that planet, its time period is |
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Answer» 3.14 sec |
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| 11. |
How much below the earth's surface the acceleration due to gravity reduces to 64% of its value on the surface of earth ? |
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Answer» Solution :`g. = (64)/(100)g` `(g.)/(g) = (R^(2))/((R+h)^(2))` `(64)/(100) = (R^(2))/((R+h)^(2))` `RARR (8)/(10) = (R )/(R + d)` `8R + 8d = 10R` `8d = 2R rArr d = (1)/(4)R` `d = (1)/(4)R = (1)/(4) XX 6,400 = 1,600 km` |
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| 12. |
A block is kept on a rough horizontal plank. The coefficient of friction between the block and the plank is 1/2. The plank is unergoing SHM of angular frequency 10 rad/s. Find the maximum amplitude of plank in which the block does not slip over the plank (g=10m//s^(2)) |
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Answer» SOLUTION :MAXIMUM acceleration in SHM is `a_("max")=OMEGA^(2)A` this will be provided to the block by friction. HENCE `a_("max")=mug` or `omega^(2)A=mug` or `a=(mug)/(omega^(2))=((1/2)(10))/((10)^(2))=0.05m=5cm` |
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| 14. |
If the linear density of a rod of length L varies as lambda=A+Bx, find the position of its centre of mass. |
Answer» Solution :LET the x-axis be along the length of the rod and origin at ONE of its ENDS. As rod is along x-axis, for all points on it y and z co-ordinates are zero.  Centre of mass will be on the rod. Now consider an element of rod of length dx at a distance x from the origin, then `dm=lambda` dx`=(A+Bx)dx` `X_(CM)=(int_(0)^(L)xdm)/(int_(0)^(L)dm)=(int_(0)^(L)x(A+Bx)dx)/(int_(0)^(L)(A+Bx)dx)` or `X_(CM)=(((AL^(2))/(2)+(BL^(3))/(3)))/(AL+(BL^(2))/(2))=(3AL+2BL^(2))/(3(2A+BL))=(L(3A+2BL))/(3(2A+BL))` |
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| 15. |
An external device, e.g., an electric motor, supplies constant power to a rotating system, e.g., a flywheel, through a torque tau. The angular velocity of the system is omega . Both tau and omega are variable |
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Answer» `omega PROP TAU` |
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| 16. |
Separation between two bodies each of mass 1 kg is 10 cm. Find the force ofGravitation between them r = 10 cm = 10^(-1) m. |
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Answer» SOLUTION :` implies F = (Gm_(1) m_(2))/r^2 = ((6.67 xx10^(-11))(1) (1))/(10^(-1))^(2)` `F = 6.67 xx10^(-9) N` |
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| 17. |
A certain person has a minimum distance of distinct vision of 150cm. He wishes to read at a distance of 25cm. What focal length glasses should he use? |
| Answer» ANSWER :B | |
| 18. |
n moles of an ideal monoatomic gas undergoes an isothermal expansion at temperature T, during which its volume becomes 4 times. The work done on the gas and change in internal energy of the gas respectively are |
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Answer» NRT In 4,0 |
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| 19. |
Is the oscillation of a simple pendulum at the centre of the earth be possible? |
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Answer» Solution :No, because the value of g at the CENTRE of earth is ZERO and hence, in periodic time `T= 2pi sqrt((l)/(g))" now PUT "g= 0` `therefore T= 2pi sqrt((l)/(0))=" INFINITE "` MEANS oscillation does not occurs. |
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| 20. |
Define uniform motion. |
| Answer» SOLUTION :If a point object covers equal distances on the circumference of the CIRCLE in equal intervals of time. Then it is said to be in UNIFORM motion . | |
| 21. |
Assertion : Inside parts of machine are jammed in winter . Reason : The viscosity of lubricant used in machine parts increase at low temperature. |
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Answer» Both assertion and REASON are TRUE and the reason is the CORRECT explanation of the assertion. |
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| 22. |
A spaceship is launched into a circular orbit of radius R close to the surface of the earth. The additional velocity to be imparted to the spaceship in the orbit to overcome the earth's gravitational pull is (g rarr acceleration due to gravity) |
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Answer» 1.414 RG |
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| 23. |
A block is placed on a horizontal platform. The system is making horizontal oscillations about a fixed point with a frequency of 0.5Hz. The maximum amplitude of oscillation if the block is not to slide on the horizontal platform, is (Coefficient of friction between the block and the platform = 0.4) |
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Answer» 0.3971m |
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| 24. |
A cannon ball is fired with a velocity of 200 ms^(-1) at an angle of 60^(@) with the horizontal. At the heighest point of its flight it explodes into 3 equal fragments. One fragment is going vertically upwards with a velocity of 100 m/s and second going vertically downwards with a velocity of 100 ms^(-1). The third fragment will be moving with a velocity of |
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Answer» `600 ms^(-1)` in the horizontal DIRECTION |
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| 25. |
An air chamber of volume V has a neck area of cross section a into which a ball of mass m just fits and can move up and down without any friction (Fig.14.27). Show that when the ball is pressed down a little and released , it executes SHM. Obtain an expression for the time period of oscillations assuming pressure-volume variations of air to be isothermal [see Fig. 14.27]. |
| Answer» Solution :`T=2pisqrt((VM)/(BA^(2)))` where B is the bulk modulus of air. For ISOTHERMAL CHANGES B=P. | |
| 26. |
Show that the function (sin omegat - cos omegat) represents simpe harmonic motion. |
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Answer» Solution :x(t) = `SINOMEGAT- COSOMEGAT` = `SQRT2(sinomegat cospi/4 - cos omegat sin pi/4)` `sqrt2sin(omegat-pi/4)` which is of the form ` ASIN(omegat+phi)` |
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| 27. |
block of mass m moving with speed v collides with another block of mass 2m at rest. The lighter block comes to rest after the collision. The coefficient of restitution is |
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Answer» `(1)/(2)` |
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| 28. |
The coefficient of linear expansion for a certain metal varies with temperatures as alpha (T). If L_(0)is the initial length of the metal and the temperature of the metal is changed from T_(0) to (T_(0) gt T), then |
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Answer» `L= L_(0) int_(T_0)^( T) ALPHA (T) dt``L= L_(0) [ 1+ int_(T_0)^(T) alpha (T) d T]` |
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| 29. |
A body is projected at an angle 30^(@) to the horizontal with a speed of 30ms^(-1). The angle made by the velocity with the horizontal after1.5 s is (g=10ms^(-2)) |
| Answer» ANSWER :A | |
| 30. |
A particle is moving in a circle of radi9us R=1 m with constnat speed v=4m/s. The ratio of the displacement to acceleration of the foot of the perpendicular drawnn from the particle onto the diameter of the circle is |
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Answer» `1/16 s^(2)` |
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| 31. |
If the K.E. of a rotating body about an axis is decreased by 36%, its angular momentum about that axis |
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Answer» INCREASES by `72%` |
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| 32. |
A block of mass 'M' is pressed against a wall with a horizontal force F. Then(a) it will slide down if the wall is smooth(b) frictional force may balance the weight if the wall is rough(c ) Normal reaction is equal to weight of the block (d) Normal reaction is zero if the wall is smooth |
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Answer» A & B are CORRECT |
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| 33. |
Explain with reason why if ice melts at pole then moment of inertia of earth increases, angular velocity omega decreases and day night will be longer? |
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Answer» SOLUTION :If ice of he pole melts then it will come towards the equator and moment of inertia of earth will INCREASE because mass particle at equator are at more distance from rotational axis as compare to pole. Time period `(T)=(2pi)/(omega)` (`:'Iomega=` constant) So if I increases then `omega` decreases. HENCE T will be INCREASED. Due to increment of time period, the DURATION of day and night will increase. |
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| 34. |
Is in necessary that we does the motion of a body on a closed loop is zero for every force in nature ?Why? |
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Answer» |
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| 35. |
In SHM, amplitude of kintetic energy is ((l)/(4))^(th) of the total energy at a displacementequal to: |
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Answer» `(A)/(sqrt(2))` Kinetic energy, `k=(1)/(2) m omega A^(2)(A^(2)-X^(2))` Total energy `E=(1)/(2)m omega^(2)A^(2)` As, `k=(E)/(4)` `:. (1)/(2)m omega^(2)(A^(2)-x^(2))=(1)/(4)((1)/(2)m omega^(2)A^(2))` (or) `4A^(2)-4X^(2)=A^(2)` (or) `4x^(2)=3A^(2)x` (or) `x=(sqrt(3))/(2)A` |
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| 36. |
A boat with a speed of 5 km *h^(-1) in still water crosses a river of width 1 km along the shortest possible path in 15 minutes. What is the velocity of the river water ? |
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Answer» |
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| 37. |
When 200J of work is done on a fly wheel its frequency of rotation increases from 4Hz to 9Hz. The M.I. of the wheel about the axis of rotation is |
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Answer» `0.15kgm^(2)` |
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| 38. |
(A) A normal human eye can cleary see allthe objects at the different distance. ( R) The human eye has the capacity to suitably adjust the focal length of its lens to a certain extent. |
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Answer» Both A and R are TRUE and R is the CORRECT explanation of A |
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| 39. |
In Column-I, system surroundings and in Column - II modes of heat transfer are given below. Match the followings : |
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Answer» (b) As substance is rear FIRE, heat will be transferred through natural CONVECTION and radiation will be there due to fire. |
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| 40. |
Consider a uniform square plate of side 'a' and mass 'm'. The moment of inertia of inertia of this plate about an axis perpendicular to its plane and passing through one of its corner is |
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Answer» `5/6"ma"^(2)` |
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| 41. |
The displacement of a particle is represented by the equation y= sin^(3) omega t. The motion is……….. |
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Answer» non-periodic `= (3sin omega t-4SIN 3 omega t)/(4)""[THEREFORE sin 3theta= 3sin THETA- 4sin^(3)theta]` `therefore V= (dy)/(dt)= (d)/(dt)[(3sin omega t-4sin 3omega t)/(4)]` `therefore 4v= 3omega cos omega t -4xx3 omega cos 3 omega t` `therefore 4v= 3omega cos omega t- 12omega cos 3 omega t` `therefore 4(dv)/(dt)= (d)/(dt) [3omega cos omega t- 12omega cos 3omega t]` `therefore 4a= -3omega^(2)sin omega t+ 36 omega^(2)sin 3 omega t` `therefore a= -(3omega^(2)sin omega t- 36 omega^(2)sin 3 omega t)/(4)` `= -omega^(2) ((3sin omega t+ 36 sin 3 omega t))/(4)` `therefore " It is not " a propto -omega^(2)y` Hence, motion is not SHM. As the expression is involvingsine function, hence it will be periodic. |
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| 42. |
The requirement for a satellite to be goestationary, it must |
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Answer» have CIRCULAR orbitin EQUATORIAL plane |
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| 43. |
A swinner capable of swimming with velocity u relative to water jumps in a flowing rever having velocity v. The man swims a distance d down stream and return back to the original position . Find out the time taken in camplete motion. |
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Answer» SOLUTION :`t=t_("down")+t_("up")` `=d/(V+U)+d/(u-v)=(2du)/(u^(2)-v^(2))` |
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| 44. |
There are three distinct modes of heat transfer.Explain briefly the occurance of a sea breeze based on heat transfer. |
| Answer» SOLUTION :TOPIC LAND and SEA BREEZES. | |
| 45. |
A dynamometer D is attached to two blocks of masses 6 kg and 4 kg.Forces of 20 N and 10 N are applied on the blocks as shown in Fig. The dynamometer reads |
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Answer» `10N` |
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| 46. |
What is menat by the dimensions of a physical quantity? |
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Answer» Solution :The dimensions of a physical quantity are the POWERS to which the units of base quantities are raised to represent a derived UNIT of that quantity. Eg. `"VELOCITY"=("Displacement")/("Time")=[[L]]/[[T]]` `[M^(0)LT^(-1)]` Hence the dimensions of velocity are 0 in mass, 1 m length and -1 in time. |
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| 47. |
Two friends A and B (each weighing 40 kg) are sitting on a frictionless platform some distance d apart. A rolls a ball of mass 4 kg on the platform towards B which B catches. Then B rolls the ball towards A and A catches it. The ball keeps on moving back and forth between A and B. The ball has a fixed speed of 5 m//s on the platform. a. Find the speed of A after he rolls the ball for the first time. b. Find the speed of A after he catches the ball for the first time. c. Find the speed of A and B after the ball has made five round trips and is held by A. d. How many times can A roll the ball? e. Where is the centre of mass of the system A + B + ball at. the end of the nth trip? |
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Answer» Solution :After Every throw `A` or `B` gains a momentum of `20 kg m//s` in the direction opposite to the motion of the ball. First round  Second Round  At the end of each round, both men receive a momentum `40 kg m//s` a. `pA=20=40 v_(A)` `v_(A)=1/2m//s` `b. p_(A,1)=40=(40+4)v_(A,1)` `v_(A,1)=40/44=10/11m//s` C. At the end of five round trips, the linear momentum of (ball `+ A` ) system, `p_(A,S)=40xx5=200kgm/s` `200=(40+4)v_(A,5)` `V_(A,5)=50/11m/s` Momenum transfered to `B` in five trips `=40xx5=200impliesv_(B,5)=5m//s` d. A can catch the ball until the velocity of `A` is less than `5 m/s`. after fie ROUNDS when `A` THROUWS the balls, i.e., `6 th` time, the velocity of `A` becomes greater than `5m//s` hence `A` can throw the ball only six times. e. `A` no external force is ACTION on As, `B` and ball system hence the postion of centre of mass of the system should remain constant always. Let the centre of mass be at a distance `x` cm from the position of `A`. `(40+4+10)x_(CM)=40xx0+4xx0+40d` `x_(CM)=(10d)/21m` from initial position of `A`. |
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| 48. |
The resultant of two forces 1 and P is perpendicular to ' 1' and equal to 1. What is the value of 'P' and angle between the forces |
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Answer» `SQRT2 N, 135^(@)` |
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| 49. |
If the masses of the Earth and Sun suddenly double, the gravitational force between them will |
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Answer» remain the same If the MASSES are doubled then the force will be `F = (G(2m_(1))(2m_(2)))/(r^(2))` `F = 4 (Gm_(1)m_(2))/(r^(2))` The gravitational force beteen them will be INCREASES 4 times . |
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| 50. |
Two satellites of earth. S_(1)" and "S_(2) are moving in the same orbit. The mass of S_1 is four times the mass of S_2. Which one of the following statements is true? |
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Answer» the potential energies of earth satellites in the two cases are EQUAL. |
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