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This section includes InterviewSolutions, each offering curated multiple-choice questions to sharpen your knowledge and support exam preparation. Choose a topic below to get started.
| 37501. |
A bullet fired into a fixed target loses half of its velocity in penetrating 15 cm. How much further it will penetrate before coming to rest? |
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Answer» 5cm |
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| 37502. |
What is the orbital radius of a geo-stationary satellite? What is the height from the surface of the earth ? |
| Answer» Solution :Orbital radius of a geo-stationary SATELLITE is 42, 250 km. Its height above the SURFACE of the earth is nearly 35,800km. | |
| 37503. |
The point where the entire weight of the body acts is called as |
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Answer» CENTER of MASS |
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| 37504. |
A smooth tunnel is dug along the radius of the earth that ends at the centre of earth. A ball is released from the surface of earth along the coefficient of restitiution is 0.2 between the end of tunnel and ball then the total distancetravelled by the ball second collision at the centre of earth is |
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Answer» `(6)/(5)R` |
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| 37505. |
A box of mass 8 kg ios placed on a roulgh inclined plane of inclination 30^(@) Its downward motion cn be prevented byu applying a horizontal force F, then value of F for which friction between the block and the incline surface is minimum is |
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Answer» `80/sqrt(3)` |
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| 37506. |
Give one example each of central force and non-central force. |
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Answer» Solution :`implies`For CENTRAL force : Gravitational force, electrostatic force. For non-central force : NUCLEAR force, magnetic force acting between two current CARRYING LOOPS. |
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| 37507. |
The kinetic energy of a given sample of an ideal gas depends only on its |
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Answer» Volume |
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| 37508. |
A given of gas occupies a volume of 100 c.c at one atmospheric and at 100^(@)C. At the same temperature, how much volume the same gas occupies at 4 atmospheric pressure ? |
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| 37509. |
The kinetic theory of gases gives the formula PV=(1)/(3)Nmv^(bar2) for the pressure P exerted by a gas enclosed in a voluem V. The term Nm represents |
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Answer» the mass of a mole of the GAS |
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| 37510. |
A man is moving with a constant velocity along a line parallel to X-axis away from the origin. Its angular momentum w.r.t origin is [Hint : L = mv times r = constant, as m, v and r are constants] |
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Answer» Zero |
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| 37511. |
The motion of a body falling from rest in a resisting medium is described by the equation (dv)/(dt)= a-bv where a and b are constants . The velocity at any time t is given by |
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Answer» `V = a/b(1-E^(BT))` |
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| 37512. |
Specific heat of oxygen at a constant pressure is 0.2174 kcal/kg K. If the ratio of its specific heat is 1.4,find the universal gas constant given that J=4200J/kcal and molecular weight of oxygen is 32. |
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Answer» Solution :We have seen that `C_(p)=(gammaR)/(gamma-1)` `C_(p)`=MOLAR heat capacity at constant pressure=Principal specific heat at constant pressure `XX` Molecular weight. As specific heat of OXYGEN at constant pressure is given on kcal//kg K. we have to convert it into J/kg K `C_(p)=0.2174xx4200xx32 J/"Kmole"` `K=(gammaR)/(gamma-1) = (1.4R)/((1.4-1))` `R=(0.2174xx4200xx32xx0.4)/(1.4) = 8348J/"kmoleK"` . |
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| 37513. |
A family uses 8 kW of power. Compare this area to that of the roof of a typical house. |
| Answer» Solution :comparable to the roof of a large house jjof DIMENSION `14M xx 14m`. | |
| 37514. |
The width of a river is 2sqrt(3) km. A boat is rowed in direction perpendicular to the banks of river. If the drift of the boat due to flow is 2km, the displacement of the boat is |
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Answer» 3 km |
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| 37515. |
A bullet of mass 10 g and speed 500 m/s is fired into a door and gets embedded exactly at the centre of the door. The door is 1.0 m wide and weighs 12 kg. It is hinged at one end and rotates about a vertical axis practically without friction. Find the angular speed of the door just after the bullet embeds into it. |
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| 37516. |
At what depth below the surface of the earth, acceleration due to gravity g will be half its value 1600 km above the surface of the earth ? |
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Answer» `4.2 XX 10^(6)` m |
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| 37517. |
A graph of potential energy V(x) verses x is shown in figure .A particle of energy E_(0) is executing motion in it . Draw graph of velocity and kinetic energy verses x for one complete cycleAFA. |
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Answer» Solution :We KNOW that Total `E = K +U ` `E = K+V(x) "" ( :. U = V(x))` `K = E_(0)-V(x) "" ( :. E =E_(0))` at A , x = 0 ,V(x) = `E_(0)` ` :.K =E_(0)-E_(0)=0` at B , `V(x) lt E_(0)` ` :. K =E_(0)` (Maximum) K=0 At F, the variation is as below ,  VELOCITY versus x graph : As `KE =1/2 mv^(2)` ` :. ` At A and F , where KE = 0 , v = 0 At C and d , KE is maximum .Therefore , v is `PM` MAX . At B . KE is positive but not maximum . Therefore , v is `pm ` some value ( `lt` max) The variation is shown in the DIAGRAM . 
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| 37518. |
Suppose there existed a planet that went around the Sun twice as fast as the earth. What would be its orbital size as compared to that of the earth ? |
| Answer» SOLUTION :SMALLER by a FACTOR of 0.63. | |
| 37519. |
The temperature of a gas is raise from 27^(@)C to 927^(@)C. The root mean squre speed of its molecules.............. . |
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Answer» become`SQRT(927)/27` TIMES the EARLIER value |
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| 37520. |
Three identical spheres each of radius R are placed on a horizontal surface touching one another. If one of the spheres is removed, the shift in the centre of mass of the system is |
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Answer» `R//2sqrt(3)` |
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| 37521. |
A uniform rod of density rho is placed in a wide tank containing a liquid of density rho_(0)(rho_(0)gtrho). The depth of liquid in the tank is half the length of the rod. The rod is in equilibrium, with its lower end resting on the bottom of the tank. In this position the rod makes an angle theta with the horizontal. Determine theta. |
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| 37522. |
A man insidea moving train throwa a baoll verticallyupwards . How will the motion of ball appears to a stationary observe (a) inside the train and (b) outside the train? |
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Answer» Solution :(a) With respect to stationary observe inside the train , ball has only one velocity component , along vertical. So, to him , the ball will APPEAR to move straight , VERTICALLYUPWARDS and then downwards . (b) With respect to observe outside the train , the ball has both COMPONENTS of velocity , horizontal and vertical. So, to him the ball will appear to move in a parabolic PATH . |
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| 37523. |
What happens in a eleastic collision of two identical bodies moving opposite to each other ? |
| Answer» Solution :The direction of VELOCITY of both BODIES BECOMES reverse and its values CHANGES . | |
| 37524. |
A horse has to apply more forse to start a cart than to keep it moving. Why ? |
| Answer» Solution :Since LIMITING friction is GREATER than KINETIC friction. | |
| 37525. |
A block of mass m is placed on a smooth sphere of radius R. It slides when pushed slightly. At what vertical distance h, from the top, will it leave the sphere? |
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Answer» `(R)/(4)`  Let the block leave the sphere at point B, which is at a distance h from the top of the sphere. `THEREFORE(mv^2)/( R ) =mg COSTHETA -N` where N is the normal reaction and v is the velocity of block at point B. When the block leaves the sphere at point B, the normal reaction N becomes ZERO. `therefore(mv^2)/( R )= mgcos thetaorcos theta =(v^2)/(Rg)` From figure,` cos theta = (R-h)/( R)` ` therefore(R-h)/(R ) = (2 gh)/(Rg) "" [:.v= sqrt(2 gh)]` ` orR-h =2hor 3h=Rorh=(R )/(3 )` |
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| 37526. |
A balloon rases up with uniform velocity 'u'. A body is dropped from ballon. The time of descent for the body is given by is |
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Answer» `SQRT((2H)/(g))` |
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| 37527. |
State and explian Stefan - Boltzmann law. |
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Answer» Solution :Stefan.s law states that the rate of emission or radiant energy by unit area of a perfectly BLACK BODY is directly proportional to the fourth power of its absolute temperature. `i.e.,E prop T^(4) or E = SIGMA T^(4) `, where `sigma` isthe Stefan.s CONSTANT. If the body is not perfectly black and its emissivity or relative emittance is .e. then `E = e sigma T^(4)` . |
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| 37528. |
If vecP + vecQ = vecR and vecP - vecQ = vecS, then R^(2) + S^(2) is equal to |
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Answer» <P>`P^(2) + Q^(2)` |
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| 37529. |
A mass of 3 kg is attached at end of rope with 6 kg mass. At upper end of rope tension will be …... . |
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Answer» |
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| 37530. |
What is the average distance between atoms (interatomic distance) in water? Use the data given in Examples 13.1 and 13.2. |
| Answer» Solution :A given mass of WATER in vapour state has `1.67 xx 10^(3)` TIMES the volume of the same mass of water in liquid state . This is also the increase in the amount of volume available for each molecule of water. When volume INCREASES by`10^(3)`times the radius increases by `V^(1//3)` or 10times, i.e., `10 xx 2 À = 20 Å`. So the average DISTANCE is `2 xx 20 = 40 Å`. | |
| 37531. |
A glass tube of diameter 0.06cm is dipped in methyl alcohol. If angle of contact is 0^@ density ofmethyl alcohol 0.8 g cm^(-3) and surface tension 0.023 Nm^(-1), the height to which it rises in the tube is |
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| 37532. |
What are the answers to (a) and (b) for an inelastic collision ? |
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Answer» Equal to10kJ |
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| 37533. |
In a hydraulic lift, the area of smaller piston is 5 cm^2. The weight raised by larger piston is 900 kgf, if a force of 150 kg fis applied on smaller piston. Calculate the area of larger piston. |
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Answer» Solution :`a=5 CM^(2) =5 xx 10^(-4) m^(2)` f=150kgf `=150 xx 9.8 N` `F=900 xx 9.8 N` As `f/a=F/A` `(150 xx 9.8)/(5 xx 10^(-4)) =(900) xx 9.8)/(A))` Solving we get `A=30 xx 10^(-4) m^(2)` |
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| 37534. |
For a stationary wave y = 10 sin ((pi x )/(4)) cos (2pi t )metre, distance between two consecutive nodes is ...... m. |
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Answer» 4 `therefore (2pi)/(lamda) = (pi)/(4) implies lamda = 8 m` Required distance `= (lamda)/(2) = (8)/(2) = 4 m` |
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| 37535. |
A solid sphere rolls down two different inclined planes of the same heights but different angles of inclination. (a) Will it reach the bottom with the same speed in each case? (b) Will it take longer to roll down one plane than the other? (c ) If so, which one and why? |
Answer» Solution :(a) In figure two inclined planes AB and AC is shown with angle of inclination `theta_(1)andtheta_(2)` respectively and have equal height h. Here `theta_(1)gttheta_(2)`.  The velocity of solid sphere at the bottom of the inclined plane of angle `theta`. `V=sqrt((2gh)/((1+(K^(2))/(R^(2)))))` Radius of gyration for sphere `K^(2)=(2)/(5)R^(2)` `therefore v=sqrt((2gh)/(1+(2)/(5)))` `therefore v=sqrt((10)/(7)gh)` In this formula there is no term of angle, MEANS the velocity of sphere at the bottom does not depend on the angle and as h is same in the two cases velocity must be same. Time taken to roll down the two planes will also be the same. (b) Yes, if solid sphere rolls down from both the slopes (1) ROLLING time from slope (1) is less and rolling time from slope (2) is more (c ) It will TAKE more time for slope (2) because acceleration of body parallel to the surface of slope of angle `theta` `a=(gsintheta)/(sqrt(1+(K^(2))/(R^(2))))` but for solid sphere `K^(2)=(2)/(5)R^(2)` `therefore a=(gsintheta)/(1+(2)/(5))=(5gsintheta)/(7)`, Here `(5)/(7)` and g are constant `therefore apropsintheta....(1)` `therefore (a_(1))/(a_(2))=(sintheta_(1))/(sintheta_(2))` [From eqn. (1)] but in first phase sin is increasing function and `theta_(1)gttheta_(2)impliessintheta_(1)gtsintheta_(2)` `IMPLIES (sintheta_(1))/(sintheta_(2))gt1` `therefore (a_(1))/(a_(2))gt1....(2)` Now in equation of motion `v=v_(0)+at,v` is same and `v_(0)=0` `therefore` at is constant `therefore a_(1)t_(1)=a_(2)t_(2)` `therefore (a_(1))/(a_(2))=(t_(2))/(t_(1))` `therefore (t_(2))/(t_(1))gt1` [`because` from eqn. (2)] `therefore t_(2)gtt_(1)` (c) Short method : Suppose `d_(1)` = distance (AB) of slope-1 `d_(2)` = distance (AC) of slope-2 `t_(1)` = time taken by slope AB `t_(2)` = time taken by slope AC Here, solid sphere rolls at the same velocity from both the slope. Hence, time taken depend on the distance of slope. If distance is more, time taken is also more. Here `d_(2)gtd_(1) [because theta_(1)gttheta_(2)]` `therefore t_(2)gtt_(1)` |
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| 37536. |
An object is projected vertically up from the earth’s surface with velocity sqrt(Rg)where R is the radius of the earth and ‘g’ is the acceleration due to earth on the surface of earth. The maximum height reached by the object is nR. Find value of n. |
| Answer» SOLUTION :YES, a BODY in CIRCULAR MOTION. | |
| 37537. |
A liquid is kept in a cylindrical vessel which is rotated along is its axis. The liquid rises at the side. If the radius of the vessel is 5cm and the speed of rotation is 4 rev/s, then the difference in the height of the liquid at the centre of the vessel and its sides is |
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Answer» 8mc |
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| 37538. |
Velocity of the body on reaching the ground is same in magnitude in the following cases (a) a body projected vertically from the top of tower of height .h. with velocity .u. (b) a body thrown down wards with velocity .u. from the top of tower of height .h. (c) a body projected horizontally with a velocity .u. from the top of tower height .h. (d) a body dropped from the top tower of height .h. |
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Answer» a, d, c and d are correct |
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| 37539. |
Number of significant digits in 20.00.......... |
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Answer» 1 |
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| 37540. |
Letbe the angular velocity of the earth's rotation about its axis. An object weighed by a spring balance gives the same reading at the equator as at height h above the poles(h lt lt R). The value of h is |
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Answer» `(OMEGA^(2) R^(2))/(g)` |
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| 37541. |
The energy possessed by a body by virtue of its motion is called as |
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Answer» POTENTIAL energy |
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| 37542. |
A body of mass 1 kg is moving with velocity 30 ms^(-1) due north. It is acted on by a force of 10 N due west for 4 seconds. Find the velocity of the body after the force ceases to act. |
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Answer» `50m//s , TAN^(-1) (3/4)` |
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| 37543. |
A system consistsof a thin ring of radius R and a very long uniform wiere oriented along axis of the ring with one of its ends coinciding with the centre of the ring. If mass of ring is m and the linearmass density of the wire is lambda, then the ineraction force between the ring and the wire is F = (KGmlambda)/(R ), Then find the value of k |
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| 37544. |
A solid cylinder and a hollow cylinder , both of the same mass and same external diameter are released from the same height at the same time on an inclined plane . Both roll down without slipping . Which one will reach the bottom first ? |
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Answer» Both together only when angle of inclination of PLANE is `45^(@)` Here , l is length of INCLINE plane For solid cylinder `K^(2) = (R^2)/(2)` For hollow cylinder `K^2 - R^2` HENCE , solid cylinder will reach the bottom first . 
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| 37545. |
Planck's constnat has the same dimensions as |
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Answer» Energy |
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| 37546. |
The distance travelled by a falling body in the last second of its motion, to that in the last but one second is 7 : 5, the velocity with which body strikes the ground is |
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Answer» 19.6 m/s |
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| 37547. |
A satellite does not need any fuel to move around the earth. Give reason. |
| Answer» Solution :The gravitational FORCE between SATELLITE and EARTH provides the centripetal force required by the satellite to move in a CIRCULAR orbit. | |
| 37548. |
The gas constant for a molecule is (terms have usual meaning) a) K b) R/N c) R/NT d) Rim |
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Answer» Only 'a' |
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| 37549. |
A simple pendulum has time period T_(1). The point of suspension is now moved upwards according to the relation =kt^(2),Ik=1m//sec^(2)) where y is the vertical displacement. The time period now becomes T_(2) then find the ratio of (T_(1)^(2))/(T_(2)^(2)) (g=10m//sec^(2)) |
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Answer» SOLUTION :`y-kt^(2)/1//2at^(2)` ACCELERATION `implies1/2a=k=1""impliesa=2m//sec^(2)` `T_(1)=2pisqrt(l/G)` and `T_(2)=2pisqrt(l/(g+a))` `(T_(1)^(2))/(T_(2)^(2))=(g+a)/g=(10+2)/10=6/5` |
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| 37550. |
A transverse harmonic wave on a string is described by y(x,t) = 3.0 sin (36 t + 0.018x + pi//4) where x and y are in cm and t in s. The positive direction of x is from left to right (a) Is this a travelling wave or a stationary wave? If it is travelling what are the speed and direction of its propagation? (b) What are its amplitude and frequency? (c ) What is the initial phase at the origin ? (d) What is the least distance between two successive crests in the wave? |
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Answer» SOLUTION :(a) A travelling WAVE. It travels from right to left with a SPEED of `20 ms^(-1)` (b) 3.0cm, 5.7Hz (C ) `pi//4` (d) 3.5m |
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