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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. |
One end of a massless spring of spring constant 100 Nm^(-1)and natural length 0.5 m is fixed and the other end is connected to a particle of mass 0.5 kg lying on a frictionless horizontal table. If the mass rotates at an angular velocity of 2 rad s^(-1), the elongation of the spring is approximately. |
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Answer» 4cm |
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| 2. |
Given displacement of a particle executing SHM y(t)=A cos (omegat+phi). Plot instantaneous displacement, velocity and acceleration of particle with respect to time. |
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Answer» Solution :`y(t)=A COS (OMEGAT+PHI)` `v(t)=-OMEGA A sin (omega t+phi)` and `a(t)=-omega^(2)A cos (omegat +phi)` and note that `""cos ((pi)/(2)+phi)=-sin phi""sin((pi)/(2)+phi)=+cos phi` `cos (pi+phi)=-cos phi""sin(pi+phi)=-sin phi` `cos((3pi)/(2)+phi)=+sin phi""sin ((3pi)/(2)+phi)=-cos phi` and `cos (2pi+phi)=+cos phi""and sin (2pi+phi)=+sin phi` 
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| 3. |
Ten litres of dry ailr at atmospheric pressure and 0^(@)C are contained in a closed vessel. Three grams of water are added and the system is heated to 100^(@)C. Find the pressure in the vessel. |
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| 4. |
Three identical discs, A, B and C rest on a smooth horizontal plane as shown in figure. The disc A is set in motion with velocity v along the perpendicular bisector of the line BC joining the centres of the stationary discs. The distance BC between the centre of stationary discs B and C is n times the diameter .d. of each disc. At what value of n will the disc A recoil, stop and move on after elastic collision? |
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| 5. |
A piece of charcoal and a piece of shining steel of the same area are kept for a long time in an open lawn in bright sun. a) The steel will absorb more heat than the charcoal b) The temperature of the steel will be higher than that of the charcoal c) If both are picked up by bare hands, the steel will be left hotter than the charcoal d) If the two are picked up from the lawn and kept in a cold chamber, the choreal will lose heat at a faster rate than the steel |
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Answer» The steel will absorb more heat than the charcoal |
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| 6. |
A train is moving due east and a car is moving due north with equal speeds. A passenger in the train finds that the car is moving towards |
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Answer» NORTH - East |
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| 7. |
A marble block of mass 2 kg lying on ice when given a velocity of 6 ms^(-1) is stopped by friction in 10 s. Then the coefficient of friction is (g=10 ms^(-2)) |
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Answer» `0.02` |
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| 8. |
The displacement of the particle along a straight line at time t is given by X=a+bt+ct^(2) where a, b, c are constants. The acceleration of the particle is |
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Answer» a `(dX)/(dt)=v=b+2ct` ACCELERATION `(d^(2)X)/(dt^2)=2c` |
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| 9. |
A ball projected from the ground with speed 10m/s at an angle of 45^(@) with horizontal. It collides with a wall at a distance 2 m from the point of projection and returns to its original position. If the coefficient of restitution between the ball and wall is 1/x, find x. |
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| 10. |
Figure shows two blocks, each of mass 2kg, connected by a string passing over two pulleys. One block rests on a smooth horizontal surface and the other blockhangs vertically. Assume pullyes to be frictionless and massless. What is the tension in the string? |
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Answer» Solution :From the free-body diagram of vertically hanging 2 KG block, `2g - T=2a`...... (i) considering the 2 kg block on the horizontal SURFACE . `T=2a`............ (ii) combining (i) and (ii) ` 2g -T=T or 2T = 2g or T=g ` Newton =9.8 N 
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| 11. |
In free body diagram, the object is represented by a |
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Answer» line |
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| 12. |
A steel ball of radius 2 xx 10^(-3) m is released in an oil of viscosity 0.232 Ns m^(-2) and density 840 kg m^(-3). Calculate the terminal velocity of ball. Take density of steel as 7800 kg m^(-3) |
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| 13. |
The graph between volumeand temperature in Charles'law is |
| Answer» Solution :a straight line | |
| 14. |
Energy not carried by which of the following waves ? |
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Answer» STATIONARY |
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| 15. |
In the above problem, if coefficient of friction for both the spheres is same and let t_(1) and t_(2) be the times when pure rolling of solid sphere and of hollow sphere is started. Then |
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Answer» `t_(1)=t_(2)` |
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| 16. |
If all the glass capillaries have same internal radius, then in which of the capillary, water will ride to move height ? |
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Answer» Solution :The height of water in the capillary `(h = (2T)/(rhogr)costheta)` doesn't depend on shapt of the capillary. So water will raise to same height in all the tubes. (However the LENGTH of water column in the tubes can be DIFFERENT)  If capillary tube of insufficient length is used : Suppose a thin capillary tube of radius `0.35 mm` is dipped in water. `T_(water) = 70 xx 10^(-3) N//m, theta rarr 0`. In this case water will rise up to height `h = (2T)/(rhogR) costheta = (2 xx 70 xx 10^(-3))/(10^(3) xx 10 xx 0.35 xx 10^(-3)) = 4cm`  Now suppose we use the shorter capillarfy of smae radius. but its length is only `2 cm`. It is slightly dipped in the water. To balance the pressure, water level will ride up in the capillary, it will reach upto the upper END of the tube, and now the contact angle will CHANGE till the pressure at same horizontal level is balanced. Balancing pressure at point `A` (inside the capillry) and point `B` (outside) `P_(0) - (2T)/(R)costheta + rhogh = P_(0) rArr h = (2T)/(rhogR)costheta` `2 xx 10^(-2) = (2 xx 70 xx 10^(-3))/(10^(3) xx 10 xx 0.35 xx 10^(-3))cos theta` `costheta = (1)/(2) rArr theta = 60^(@)`. So water level will reach to the topmost point of the capillary `(= 2cm)` and now contact angle wil change to `60^(@)`, Water will not OVERFLOW out of upper end in the form of fountain. |
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| 17. |
The amplitude of damped oscillator becomes 1/3 in 2 s. Its amplitude after 5 s is 1/n timesthe original. The value of n is |
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Answer» `2^(3)` |
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| 18. |
Show that a stretched wire cannot remain horizontal when a weight is suspended from its mid-point. |
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Answer» SOLUTION :Let the two ends A and Bof the wire be rigidly fixed anda weight W besuspended from the mid-point O. In this condition, the two parts of the string OA and OB make equal angles `THETA` with thehorizontal and the tension on eachpart is T [Fig.2.77].  For equilibrium, the vertical components of T on each wire together balance the weight W and the horizontal components balance each other. `therefore 2T sin theta =W or, sin theta =W/(2T)` Since, T cannot be infinitely large and `W NE 0`, `sintheta ne 0 i.e., theta ne 0^@` Hence, the wire cannot remain horizontal when a WEIGHTIS suspended from its mid-point (or from any otherpoint along its length). |
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| 19. |
What is lunar month? |
| Answer» SOLUTION :It is the time taken by MOON to complete one revolution AROUND the earth. | |
| 20. |
Four capillary tubes T_(1),T_(2),T_(3) and T_(4) having bores of radii 0.1 cm, 0.2 cm, 0.3 and 0.4 cm are dipped vertically in water. Descending order of capillary rises is |
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Answer» `T_(2),T_(3),T_(4),T_(1)` |
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| 21. |
In Column-I physical quantity and in Column -II its dimensional formula is givne. Match them properly : {:("Column-I","Column-II"),("(1) Moment of force",(a) M^1L^1T^-1),("(2) Angular momentum",(b) M^1L^2T^-1),("(3) Linear momentum",(c) M^1L^2T^-2):} |
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| 22. |
A circular disc is rotation about its natural axis with angular velocity of 10rads^(-1). A second disc of same mass is joined to it coaxially. If the radius of disc is half of the radius of the first, then they together rotate with an angular velocity of |
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Answer» `2.5"rads"^(-1)` |
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| 23. |
State the expressions for the moment of inertia of a hollow cylinder and a solid cylinder about the axis of symmetry |
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Answer» Solution :M.O.I of SOLID cylinder about axis of symmetry is`I=(MR^(2))/(2)` M.O.I of a HOLLOW cylinder about axis of symmetry is `I=MR^(2)` |
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| 24. |
A body is thrown vertically upwards with initial velocity 'u' reaches maximum height in 6 seconds. The ratio of distances travelled by the body in the first second and seventh second is |
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Answer» `1:1` |
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| 26. |
For a particle executing simple harmonic motion select correct relation for the acceleration of the particle. Where omega is the angular frequency of the particle. |
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Answer» Acceleration `=- omegaxx` DISPLACEMENT |
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| 27. |
A body of mass 2 kg is allowed to slide down along a quadrant of a circle from the horizontal position. In reaching to the bottom. Its velocity is 6m"/"sec. The work done in overcoming the friction is 10J. The radius of circle is (g= 10ms^(-2)) |
| Answer» ANSWER :D | |
| 28. |
A cubical wooden block of side 3 cm floats on water kept in a vessel. The lower face of the cube just touches the free end of a vertical spring fixed at the bottom of the vessel. Find the maximum weight that can be put on the block so that the weight does not touch water. The specific gravity of wood = 0.8 , the force constant of the spring = 50N*m^(-1)andg=10m*s^(-2). |
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| 29. |
A solid sphere of mass M and radius R is placed on a smooth horizontal surface. It is given a horizontal impulse J at a height h above the centre of mass and sphere starts rolling then, the value of h and speed of centre of mass are – |
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Answer» `h=(2)/(5)R and v=(J)/(M)` `F XX h=(2)/(5) mR^(2)xx ALPHA` and F = ma (where `a=R alpha`) `:.` mah `=(2)/(5) mRa rArr h=(2)/(5)R` ALSO impulse = change in momentum or `J=Mv` |
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| 30. |
A person driving a car suddenly applies the brakes on seeing a child on the road ahead. If he is not wearing seat belt, he falls forward and hits his head against the steering wheel. Why |
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Answer» SOLUTION :WHENA persondriving acarsuddenly appliesthe breaksthe upperpartof the bodycontinueto moveforwarddue toinertialof motion.Lowerpart of the bodyslowdownwith CAR. If henotwearingseatbelthe fallsforward andcanhit his HEAD againststeeringwheel. |
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| 31. |
Modulus of rigidity of an ideal liquid is ...... |
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Answer» INFINITY |
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| 32. |
A closed container of volume 0.02m^(3) contains a mixture of neon and argon gases at a temperature of 27^(@)C and pressure of 1xx10^(5)N//m^(2). The total mass of the mixture is 28gm. If the gram molecular weights of neon and argon are 20 and 40 respectively, find the masses of the individual gases in the container, assuming them to be ideal. |
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Answer» SOLUTION :If the mass of neon is .m., the mass of argon will be (28 - m), so `n_(Ne)=m/20andn_(Ar)=((28-m))/40` `thereforen=n_(Ne)+n_(Ar)=m/20+((28-m))/40=(28+m)/40" "...(1)` `n=(PV)/(RT)=(1xx10^(5)xx0.02)/(8.314xx300)=0.8" "...(2)` So from equations (1) and (2), `(28+m)//40 = 0.8,i.e.,m=4gm` so `m_(Ne)=4gmand m_(Ar)=28-4=24gm` |
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| 33. |
Calculate the work done if a particle displaces through (2hati-hatj+5hatk) meter under a force (4hati+2hatj-hatk) newton. (work=vecF.vecs) |
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Answer» SOLUTION :`vecF.vecS=(4veci+2vecj-).(2veci-vecj+5veck)` `(4xx2)+(2xx-1)+(-1xx5)` 1 JOULE |
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| 34. |
A body moving with a speed 10ms^(-1) due north takes a left turn through 60^(@) and continues at the same speed. The change in its velocity is |
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Answer» `10 ms^(-1) 60^(@)` S of W |
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| 35. |
Two particles start oscillating together in shm along the same straight line. Their periods are 2 s and 4 s. What is their phase difference afterls from the start? |
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Answer» |
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| 36. |
A shower of rain appears to fallvertically downwards with a velocity of 12 kmph on a person walking west wards with a velocity of 5 kmph. The actual velocity and direction of the rain are |
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Answer» 7.5 KMPH, CLOCKWISE to vertical |
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| 37. |
A metallic rod is continuously heated at its two ends, the flow of heat through the rod does not depend upon : |
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Answer» The AREA of cross-section of the rod |
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| 38. |
A body falls freely from a height .h. its average velocity when it reaches earth is |
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Answer» `SQRT(GH)` |
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| 39. |
Statement 1 refers assertion and statement 2 referes reason in the following question. Statement 1: A stone is tied to a string is whirled in a circle with uniform velocity. If the string suddely breaks, the angular momentum of the stone becomes zero. Statement 2: The torque acting on the stone equals the rate of change of angular momentum. Which one of the following statements is correct? |
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Answer» Statement 1 and 2 are true and statement 2 is a correct explanation for statement 1. |
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| 40. |
A sphere of diameter 6 cm and mass 250 g is floating in a beaker containing a liquid. When the temperature is raised, the sphere just begins to sink at a temperature of 30^@C . The density of the liquid at 0^@Cis 2.92 g//cm^3. If the expansion of the sphere is ignored, the coefficient of cubical expansion of the sphere is gamma , then (10^9 gamma)/(13837) = 2^a 3^b 11^c . Compute the value of (ab)/(c ) |
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Answer» Volume of the sphere, `V = 4/3 pi r^3 = 4/3 xx 22/7 xx 3^2` ` = 264/3 cm^3` Mass of the sphere, m = 250 g Density of the sphere, `rho = m/V = (250 xx 3)/(264) = 2.84 g//cm^3` Given, density of liquid at `0^@C, rho_0 = 2.92 g//cm^3` When the temperature of the BEAKER is raised, the liquid expands and its density decreases. When the sphere just floats, Density of liquid at `30^@C`= Density of the body ` therefore rho_1 = 1.84 g//cm^3 , rho_0 2.92 g//cm^3` ` Delta T = 30^@C` Coefficient of cubical EXPANSION is `gamma = (rho_0 - rho_t)/(rho_0 Delta T) = (2.92 - 2.84)/(2.92 xx 30)` = 0.000913242 ` 10^9 gamma = 913242` `(10^9 gamma)/(13837) = (913242)/(13837) = 66 = 2 xx 3 xx 11` ` therefore a = b = c = 1` |
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| 41. |
Define a coherent system of units. |
| Answer» Solution :A SYSTEM based on a certain set of BASIC or fundamental units without USING any proportionality constants is CALLED a coherent system of units. | |
| 42. |
On increasing the filament current, the |
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Answer» WAVELENGTH of X-rays is increased |
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| 43. |
Two rectangular rods of Thermal resistance 5" Kw"^(-1) and 10" Kw"^(-1) are joined in Parallel combination. Their equivalent Thermal Resistance will be |
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Answer» `15" KW"^(-1)` |
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| 44. |
A hollow sphere of glass whose external and interanl radii are 11 cm and 9 cm respectively, is completely filled wihc ice at 0^(0)C is placed in a bath of boiling water (at 100^(0)C). Given, density of ice is 0.9" g cm"^(-3), latent heat of fusion of ice is 80" cal g"^(-1) and thermal conductivity of glass is 0.002 cal "cm"^(-1)"s"^(-1)""^(0)C^(-1). Choose the correct options. |
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Answer» Rate of melting of ICE is NEARLY `(PI)/(2)gs^(-1)` |
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| 45. |
If the average translational kinetic energy of molecule in a gas is equal to the kinetic energy of an electron acceleration from rest through 10 V , then the temperature of the gasmolecule is(Boltzmann constant= 1 . 38 xx 10^(-23) JK ^(-1) ) |
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Answer» `73.7K` |
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| 46. |
The distance covered by a body in time ( 40.0 pm 0.4) m is (5.0 pm 0.6)s. Calculate the speed of the body. The percentage error in the speed is |
| Answer» ANSWER :A | |
| 47. |
A mass 'M' is suspended by a rope from a rigid support. It is pulled horizontally with a force F. If the rope makes an angle 'theta' with vertical in equilibrium, then the tention in the string is |
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Answer» F SIN `THETA` |
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| 48. |
The error in the measure of length of a simple pendulum is 0.1% and error m the time penod is 2%. The possible maximum error in the quantity having dimensional formula LT^(-2) is |
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Answer» `1.1%` |
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| 49. |
A man walks at a speed of 6km//hr for 1 km and 8km//h for the next 1 km . What is his average speed for the walk of 2 km? |
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Answer» Solution :Distance traveled is 2 km Time taken `=(1KM)/(6km//hr)+(1km)/(8km//hr)` `(1/6+1/8)hr=7/(24)hr` Average SPEED `=(2kmxx24)/(7HR)=(48)/7 km//hr=7km//hr.` |
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| 50. |
Define centre of mass. Write down its mathematical form. Two particles (2 cm, 3 cm ) and ( 4 cm , 5 cm ) respectively. Find the position vector of the centre of mass of the two particles. |
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Answer» Solution :`X= (2xx2+3xx4)/(2+3)=(4+12)/(5)=(16)/(5)=3.2` cm `y= (2xx3+3xx5)/(2+3)=(6+15)/(5)=4.2` cm `:.` POSITION vector of the CENTRE of mass `vecr=xhati+yhatj=(3.2hati+4.3hatj)cm` |
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