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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 wire 10 m long is loaded by a mass of 250 kg. Its radius is 0.5 mm. It elongates by 10 cm. It suddenly breaks. The density of material of wire is 9000 kg/m and specific heat 420 J/Kg/K. Find the rise in temperature. |
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| 2. |
An object is projected vertifxlly up with an initial velocity u and is allowed to fallunder gravity. Draw its Acceleration-time graph |
Answer» SOLUTION :
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| 3. |
An object is projected vertifxlly up with an initial velocity u and is allowed to fallunder gravity. Draw its Velocity -time graph |
Answer» SOLUTION :
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| 4. |
An electron and a proton are detected in a cosmic ray experiment, the first with kinetic energy 10 keV and the second with 100 keV. Which is faster, the electron or the proton? Obtain the ratio of their speeds. (electron mass =9.11 xx 10^(-31)kg, proton mass =1.67xx 10^(-27)kg, 1eV= 1.60 xx 10^(-19)J ) |
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Answer» `13.53` |
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| 5. |
A disc of mass m and radius R is rolling on horizontal ground with linear velocity v. What is the angular momentum of the disc about an axis passing through bottommost point and perpendicular to the plane of motion ? |
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Answer» `(3)/(2) MVR` |
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| 6. |
An object is projected vertifxlly up with an initial velocity u and is allowed to fallunder gravity. Draw its Speed-time graph |
Answer» SOLUTION :
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| 7. |
An object is projected vertifxlly up with an initial velocity u and is allowed to fallunder gravity. Draw its Position-time graph |
Answer» SOLUTION :
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| 8. |
Is surface tension a vector ? |
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Answer» SOLUTION :Surface tension is a scalar quantity . Surface tension `=("Work")/("AREA of surface")` The amount of work DONE in increasing the unit area of liquid surface is CALLED surface tension. The work is a scalar quantity and hence surface tension is ALSO scalar quantity. |
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| 9. |
Two metal rods are fixed end to end between two rigid supports as shown in figure. Each rod is of length l and area of cross-section is A. When the system is heated up, determine the condition when the junction between rods does not shift? (Given : Y_(1) and Y_(2) are Young's modulus of materials of the rods alpha_(1) and alpha_(2) are coefficients of linear expansion) |
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Answer» `y_(1) alpha_(1) = y_(2) alpha_(2)` |
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| 10. |
The Young's modulus and rigidity modulus of a metal are 40 GPa and 20 GPa respectively. Then the bulk modulus is |
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Answer» 13.33GPa |
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| 11. |
If a spring has time period 'T' and cut into 'n' equal parts, then the time period of each part will be |
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Answer» `Tsqrt(N)` |
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| 12. |
A stone of mass 0.5 kg is attached to a string of length 2 m and is whirled in a horizontal circle. If the string can with stand a tension of 9N, the maximum velocity with which the stone can be whirled is: |
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Answer» `6 ms^(-1)` |
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| 13. |
These particles are projected vertically upward from a point on the surface of the earth with velocities sqrt((2gR//3)), sqrt((gR)), sqrt((4gR//3)) respectively where R is the radius of the earth and g is the acceleration due to gravity on the surface of the earth. The maximum heights attained are respectively h_(1), h_(2), h_(3) |
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Answer» `h_(1) : h_(2) = 2: 3` |
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| 14. |
What is the maximum speed with which a cyclist can move without skidding, in a circular path of radius 10 m, on a road where the coefficient of friction between the tyre and the road is 0.5 ? |
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| 15. |
A disc of radius 10 cm is rolling on a horizontal surface. The velocity of its centre is "4ms"^(-1) and angular velocity of rotation of the disc is "50 rads"^(-1). What is the distance (in cm) of instantaneous axis of rotation from the centre of the disc ? |
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| 16. |
A force of 5N acts on a body for 2 ms. If the mass of the body is 5g, calculate the change of velocity. |
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| 17. |
(A) Owls can move freely during night ( R) Owls have large number of rods on their retina. |
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Answer» Both A and R are true and R is the CORRECT explanation of A |
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| 18. |
What will be the difference observed when one heats mercury and water from 0^(@)C ? |
| Answer» Solution :Mercury expands continuously from `0^(@)C` when heat is supplied to it. But when WATER is heated from `0^(@)C`, it contracts up to `4^(@)C`, attains a minimum VOLUME,and then expands LIKE other liquids from `4^(@)C.` | |
| 19. |
The acceleration of10 kg block when F = 30 N , |
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Answer» `2 m// s^(2)`  Common ACCELERATION  `a_(C) = (F)/(M_(1) + M_(2)) = (30)/(15) = 2m//sec^(2)` `f_(2) - f_(1) = 5 xx a` as `"" f_(2) - f_(1) = 35 Ngt f_("required")` [`f_("required")` to have common acceleration = 10 N] |
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| 20. |
The vessels shown in the figure has two sections of areas of cross - section A_(1)andA_(2). A liquid of density rho fills both the sections, up to a height h is each. Neglect atmospheric pressure. a) The pressure at the base of the vessel is 2hrhog. b) The force exerted by the liquid on the base of the vessel is 2hrhogA_(2). c) The weight of the liquid is lt2hrhogA_(2). d) The walls of the vessels at the level X exert a downward force hrhog(A_(2)-A_(1)) on the liquid. |
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Answer» a, and C are CORRECT |
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| 21. |
pseudo force |
| Answer» SOLUTION :A pseudoforceis aforcethatarisesdue tothenon-inertialnatureof theframeconsideredIt has noorigin. | |
| 22. |
A capillary tube of radus r is immersed in water and water rises in it to a height h. The mass of water in the capillary tube is 5g . Another capillary tube of radius 2r is immersed in water. The mass of water that will rise in this tube is ……. |
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Answer» `2.5g` MASS of water in the FIRST tube , `m=pir^(2)hrho=pir^(2)xx((2Tcostheta)/(rrhog))xxdelta` `=(2pirTcostheta)/(g)` `thereforempropttr therefore(m.)/(m)=(2r)/(r)=2` or `m.=2m=2xx5g=10g` |
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| 23. |
In the given figure a ring of mass m, is kept on a horizontal surface while a body of equal mass 'm' attached through a light string, which is wounded on the ring, When the system is released the ring rolls without slipping. Choose the correct option (Ngelect mass of the pulley) |
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Answer» Acceleration of the centre of mass of ring is 2g/3 |
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| 24. |
A motor is used to lift water from a well of depth 10m and to fill a water tank of volume 30m^(3) in 10 minutes. The tank is at a height of 20m above ground. If 20% of energy is wasted, the power of the motor is |
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Answer» 18.75 kW |
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| 25. |
The breaking stress for a metal is 7.8 xx 10^9 Nm^-2. Calculate the maximum length of the wire of this metal which may be suspended breaking. The density of the metal =7.8 xx 10^3kg m^-3. Take g =10 N kg^-1 |
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Answer» Solution :BREAKING stress = Maximum stress that the wire can withstand = `7.8 xx 10^(9) Nm^(–2)` When the wire is suspended vertically, it tends to break under its own weight. LET its length be I and cross-sectional area A. Weight of wire = mg = VOLUME `xx` density `xx` g = `Alrho`g Stress=` ("Weight")/(A)= Alrhog//A=lrhog` For the wire not to break, `lrho` g = Breaking stress = `7.8 xx 10^(9) Nm^(–2)` `:. "" l=(7.8xx10^(9))/(rhog)=(7.8xx10^(9))/(7.8xx10^(3)xx10)=10^(5)`m. |
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| 26. |
A uniform cylinder of length L and mass M having cross sectional area A is suspended , with its length vertical, from a fixed point by a massless spring of spring constant k,such that it is half submerged in a liquid of density sigma at equilibrium position. What is the extension of the spring when it is in equilibrium? |
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| 27. |
Figure (a) shows P-Tcurve of an ideal gas during a process. Does compression or expansion takes place when the gas in heated ?" " |
| Answer» Solution :We draw costant volume LINES (isochores) throughthe initial and final `1 "and" 2` (see EXAMPLE 71) . The volume `V_(2)` is greater than `V_(1)`. Hence during heating of the gas EXPANSION took place. | |
| 28. |
The radius in kiometers to which the present radius of the earth (R = 6400 km ) is to be compressed so that the escape velocity is increases to ten times is |
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Answer» 6.4 |
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| 29. |
The driver of a trucksuddenly finds a wall in front of him. To avoid collision with the wall he should |
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Answer» APPLY brake at once |
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| 30. |
Identify the correct order in which the value of M.I. decreases for the following (i) M.I. of solid sphere of mass 'M' and radius 'R' about its diameter of rotation (ii) M.I. of uniform ring of mass 'M' and radius 'R' about its 'R' about its tangent perpendicular to its plane (iii) M.I. of uniform disc of mass 'M' and radius 'R' about its diameter (iv) M.I. of a uniform solid cylinder of mass 'M' about its own axis rotation |
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Answer» iii, I, iv, II |
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| 31. |
Two circular rings of equal mass and radius are placed touching each other. The moment of inertia of the system about tangential axis in the plane of system passing through point of contact of rings is |
| Answer» Answer :A | |
| 32. |
The coefficient of performace of a refrigerator is 5. If the temperature inside freezer is - 20^(@)C, the temperature of the surroundings to which it rejects heat is |
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Answer» `11^(@)C` where `T_(1)` and `T_(2)` are the temperature of HOT and COLD reservoirs (in kelvin) respectively. Here, `alpha = 5, T_(2) = -20^(@)C = -20 + 273 K = 253 K, T_(1) = ?` `:. 5 = (253 K)/(T_(1) - 253 K)` `5T_(1) - 5(253 K) = 253 K = 6(253 K)` `T_(1) = (6)/(5)(253 K) = 303.6 K = 303.6 - 273 = 30.6^(@) ~~ 31^(@)C` |
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| 33. |
A body is sliding down a rough inclined plane of angle of inclination thetafor which the coefficient of friction varies with distance x as mu(x) = kx, where k is a constant. Here x is the distance moved by the body down the plane. The net force on the body will be zero at a distance x_(0) given by : |
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Answer» `(TAN THETA)/(K)` |
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| 34. |
The earth is assumed to be a sphere of radius R. A platform is arranged at a height R from the surface of the earth. The escape velocity of a body from this platform is fu, where v is its escape velocity from the surface of the earth the value of f is .......... |
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Answer» `1/sqrt2` If a body of MASS m isprojected at height R from the surface of earth with the velocity `v_e` so that it goes beyond the earth.s gravitational field and escape from earth then , `1/2 mv_e^2 =(GM)/(2R) .m` `:. v_e = sqrt((GM)/R) " or " v_e = sqrt(gR)` Now `,v = sqrt(2gR) ` for `v = sqrt2 v_e ` or `v_e =1/sqrt2 v` `:. f =1/sqrt 2` |
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| 35. |
In the question number 66, if wheel starts from rest, what is the kinetic energy of the wheel when 2 m of the cord is unwound? |
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Answer» 20 J As `tau=FR=(25)N(0.2)m = 5Nm` Moment of inertia of flywheel about its axis is `I=(MR^(2))/(2) = ((20kg)(0.2m)^(2))/(2) = 0.4 kg m^(2)` As `tau=Ialpha` `therefore` Angular accelerations of the WHEEL, `alpha=tau/I = (5Nm)/(0.4 kg m^(2))=12/5 rad s^(-2)` Angular displacement of wheel, `theta= ("LENGTH of unwound string")/("Radius of the wheel")= (2m)/(0.2m)=10 rad` LET `omega` be final angular velocity. As `omega^(2) = omega_(0)^(2)+2alphatheta` since, the wheel starts from rest, therefore `omega_(0)=0` `therefore omega^(2) = 2 x (12.5 rad s^(-2))(10 rad) = 250 rad^(2)s^(-2)` `therefore` Kinetic energy gained, `K=1/2Iomega^(2)` `K=1/2 xx 0.4 kg m^(2) xx 250 rad^(2)s^(-2)= 50J` |
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| 36. |
Explain the different types of modulus of elasticity. |
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Answer» Solution :From Hooke.s law, the stress in a body is proportional to the corresponding strain, provided the deformation is very SMALL. Here we shall define the elastic modulus of a given material. There are three types of elastic modulus. (a) Young.s modulus (b) Rigidity modulus (or Shear modulus) (e) Bulk modulus Young.s Modulus: When a wire is stretched or COMPRESSED, then the ratio between tensile stress (or compressive stress) and tensile strain (or compressive strain) is defined as Young.s modules. `"Young modulus of a material"= ("Tensile stress or compressive stress")/("Tensile strain or compressive strain")` `Y= (sigma_(t))/(epsilon_(t))` S.I. unit of Young modulus is `N m^(2-)` or PASCAL.Bulk modulus: Bulk modulus is defined as the ratio of volume stress to the volume strain. Bulk modulus, `K = ("Normal (Perpendicular) stress or Pressure")/("Volume strain ")` The normal stress or pressure is`stigma_(n)= (F_(N))/(DeltaA)= DeltaP` The volume strain is `epsilon_(v)= (DeltaV)/(V)` Therefore, Bulk modulus is `K= -(sigma_(n))/(epsilon_(v))= (DeltaP)/( (DeltaV)/(V))` The NEGATIVE sign indicates when pressure is applied on the body, its volume decreases. Further, the equation implies that a material can be easily compressed if it has a small value of bulk modulus. In other words, bulk modulus measures the resistance of solids to change in their volume. For an example, we know that gases can be easily compressed than solids, which means, gas has a small value of bulk modulus compared to solids. The S.I. unit of K is the same as that of pressure i.e., `N m^(-2)` or Pa (pascal). The rigidity modulus or shear modulus: The rigidity modulus is defined as the ratio of the shearing stress to shearing strain, `eta_(R)= ("shearing stress")/(( "angle of shear or shearing strain")` The shearing stress is `sigma_(s)= ("Tangential force")/("area over whichit is applied")= (F_(t))/(DeltaA)` The angle of shear or shearing strain`epsilon_(s)= (x)/(h)= theta` Therefore, Rigidity modulus is `eta_(R)= (sigma_(s))/(epsilon_(s))= ((F_(t))/(DeltaA))/((x)/(h))= ((F_(t))/(DeltaA))/(theta)` Further, the above implies, that a material can be easily TWISTED if it has small value of rigidity modulus. For example, consider a wire, when it is twisted through an angle `theta`, a restoring torque is developed, that is `tau prop theta` This means that for a larger torque, wire will twist by a larger amount (angle of shear `theta` is large). Since, rigidity modulus is inversely proportional to angle of shear, the modulus of rigidity is small. The S.I. unit of `eta_(R)` is the same as that of pressure i.e., `N m^(-2)` or pascal. |
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| 37. |
The force acting on a particle moving alongx - axis varies with the position of the particle shown in the figure then body is in stable equilibrium at 1) x = x_(1) 2) x = x_(2) 3) both x_(1) and x_(2) 4) neither x_(1) nor x_(2) |
| Answer» Solution :If particle at `x_(2)` is displaced to RIGHT, the FORCE on it is negative and is BROUGHT BACK to `x_(2)`. Similarly if particle is displaced to left, the force on it is positive and is again brought back to `x_(2)`. Hence the particle is in stable equilibrium at `x_(2)`. | |
| 38. |
The square of the resultant of two forces 4N and 3N exceeds the square of the resultant of the two forces by 12 when they are mutually perpendicular. The angle between the vectors is |
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Answer» `30^(@)` |
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| 39. |
Stem correction' in plantium resistance thermometers are eliminated by the use of |
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Answer» cells |
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| 40. |
Give relation between displacement and pathlength ? |
| Answer» SOLUTION :PATH LENGTH `GE` DISPLACEMENT. | |
| 41. |
A particle moves according to the equation t= sqrtx +3, where will be the particle come to the rest for the first time |
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Answer» Solution :`x=(t-3)^(2)""x=t^(2)-6t+9` `v=(DX)/(DT)=2t-6 ""0=2t-6 RARR t=3s` |
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| 42. |
On the basis of the moduli of elasticity , distinguish between solid, liquid and gaseous substances. |
| Answer» Solution :We know that there are three moduli of elasticity- 1. Young.s modulus 2. BULK modulus and 3. modulus of rigidity. Since solids have definite length, VOLUME and shape, it has all the three moduli of elasticity. Liquid and gaseous substances have no difinite length or shape, but have volume only. Hence a liquid or a gaseous substance only has bulk modulus. This modulus of a GAS is MUCH less than that of a liquid. But the bulk moduli of a solid and a liquid are nearly equal in magnitude. | |
| 43. |
The ratio of K^(2)//R^(2) of a thin uniform ring about an axis passing through the center and perpendicular to the plane is |
| Answer» ANSWER :A | |
| 44. |
A needle of length 3 cm is floating on the surface of water. Calculate the minimum force needed to lift the needle above the surface of water. Surface tension of water is 0.072 N/m. |
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Answer» |
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| 45. |
If the velocity of a rotating body of mass 50 kg is given by barV=3bari+4barj+5bark and radius vector barr=2 bari+3barj+4bark. Then its angular momentum is |
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Answer» `50 bari+50 barj+50 BARK` |
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| 46. |
A long horizontal rod has a bead which can slide along its length and is initially placed at a distance L from one end A of the rod. The rod is set in angular motion about A with a constant angular acceleration, alpha. If the coefficient of friction between the rod and bead is mu, and gravity is neglected, then the time after which the bead starts slipping is : |
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Answer» `SQRT((MU)/(ALPHA))` |
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| 47. |
Two 10 kg bodies are attached to a spring balance as shown in figure. The reading of the balance will be |
| Answer» Answer :B | |
| 48. |
A particle is moving in a circular path whose portion vector is given by barr= (acost)hat i +(asin t)hat jthen, the tangential component of acceleration at t= (pi)/(2)sec is |
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Answer» 0 |
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| 49. |
If the mass of each molecule of a gas is halved and speed is doubled , find the ratio of initial and final pressure. |
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Answer» Solution :LET initial and FINAL pressures be `P_1 and P_2` Here, `M_1 = M, C_1 = C, V_1 = V,` `M_2 = M//@, C_2=2C,V_2=V,` As `P_1 = 1/3 M_1/V_1C_1^2` `P_2 =1/3M_2/V_2C_2^2` Ratio of PRESSURE : `:.P_1/P_2=M_1/M_2xxV_2/V_1xxC_1^2/C_2^2` `=M/(M//2)xxV/Vxx(C/(2C))^2=1/2` |
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| 50. |
Figure shows the pressure P versus volume V graphs for two different gas sample at a given temperature. M_A and M_B are masses of two samples, n_A and n_B are numbers of moles. Which of the following must be incorrect. |
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Answer» `M_A GT M_B` `RARR n_1 gt n_2` |
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