40048 + Interview Questions in Physics in Class 11

1.	A solid sphere of mass M and radius R having moment of inertia about an axis passing through the centre of mass as I, is recast into a disc of thickness I, whose moment of inertia about an axis passing through its edge and perpendicular to its plane remains I. Then, radius of the disc will be
Answer» `(2R)/(sqrt(15))` `R sqrt((2)/(15))` `(4R)/(sqrt(15))` `(R)/(4)` Solution :Moment of INERTIA of solid sphere of mass M and RADIUS R about an axis passing through the centre of mass is `I = (2)/(5) MR^(2)` . Let the radius of the disc be r . Moment of inertia of circular disc of radius r and mass M about an axis passing through the centre of mass and perpendicular to its plane`= (1)/(2) Mr^(2)` Using theorem of parallel axes , moment of inertia of disc about its edge is `I. = (1)/(2) Mr^(2) + Mr^(2) = (3)/(2) Mr^(2)` Given `I = I. therefore (2)/(5) MR^(2) = (3)/(2) Mr^(2) or r = (2R)/(sqrt(15))`

Discussion

2.	An elevator is provided with a weighing machine ( making use of principle of spring balance ) at its floor . A man weighing 60 kg stands on the platform of the machine and finds that the reading shoots to 62 kg when the elevator starts and then comes down to 60 kg again. How do you explain this ?
Answer» Answer :INITIALLY moves with acceleration `0. 33 MS^(-1)` and then at a CONSTANT upward SPEED

Discussion

3.	One end of a 100 cm long rod is fixed. At its free end a screw is attached and the pitch of the screw is 0.5 mm. The rod can move along its length on turning the screw. The screw has a circular scale with 100 divisions. It moves by one small scale division of 0.5 mm per turn. At 20^(@)C, the pitch scale reads a little over zero and the circular scale reads 92. When the temperature is increased to 100^(@)C,the pitch scale reading changes to a little above 4 divisions and the circular scale reading is 72. Find the coefficient of linear expansion of the material of the rod.
Answer» SOLUTION :Screw pitch = 0.5 mm and total number of circular scale divisions = 100 `therefore` Least count of screw `""="screw pitch"/"total no. of circular scale divisions"=0.5/100mm` `therefore` The reading of the screw scale at `20^(@)C` `"" =0 times 0.5+92 times 0.005=0.46mm,` and the reading on that scale at `100^(@)C` `"" =4 times 0.5+72 times 0.005=2.36mm` `therefore` The LINEAR EXPANSION of the rod `""=2.36-0.46=1.9mm=0.19cm` `therefore` COEFFICIENT of linear expansion of the material of the rod `"" =0.19/(100 times (100-20))=2.375 times 10^(-5@)C^(-1)`

Discussion

4.	A simple pendulum is an object suspended by a weightless and inextensible string fixed rigidly to a support. The period of oscillation of the pendulum is T. What will be the period if the pendulum is suspended in a lift moving down with an acceleration equal to g/3.
Answer» `2πsqrt(3L/2g)`. `πsqrt(3L/g)`. `2πsqrt(3L/g)`. `2πsqrt(2L/3g)`. ANSWER :A

Discussion

5.	Speed is always non-zero.
Answer» ANSWER :FALSE. It can be ZERO but it cannot be NEGATIVE.

Discussion

6.	A boat containing some pieces of material is floating in a pond. What will happen to the level of water in the pond, if on unloading the pieces in the pond, the pieces (a) float (b) sink?
Answer» Solution :If M is the mass of boat and m is the mass of pieces in it, then initially as the system is floating, `M+m=V_(D)rho_(w)` i.e., the system displaces water `V_(D)=(M)/(rho_(w))+(m)/(rho_(w))""......(1)` When the pieces are dropped in the pond, the boat will STILL FLOAT, so it displaces water `M=V_(1)rho_(w)` i.e., `V_(1)=(M//rho_(w))`. (a) Now if the unloaded pieces floats in the pond, the water displaced by them `m=V_(2)rho_(w),i.e.,V_(2)=(m//rho_(w))`. So the total water displaced by the boat and the floating pieces `V_(1)+V_(2)=(M)/(rho_(w))+(m)/(rho_(w))...(2)` which is same as the water displaced by the floating system initially (Eqn, 1), so the level of water in the pond will remain unchanged. (b) Now if the unloaded pieces sink the water diplaced by them will be equal to their own volume, i.e., `V_(2)^(1)=(m)/(rho)" "["as "rho=(m)/(V)]` and so in this SITUATION the total volume of water displaced by boat and sinking pieces will be `V_(1)+V_(2)^(1)=((M)/(rho_(w))+(m)/(rho))""....(3)` Now as the pieces are sinking `rhogtrho_(w)`, so this volume will be lesser than initial water displaced by the floating system (Eqn. 1), so the level of water in the pond will GO down (or fall).

Discussion

7.	Whena particleis in uniform motion it doesnot have
Answer» radial velocity and radial ACCELEATION radial velocity and trasverse acceleration transversevelocity and radial acceleration transverse velcoityand transverse acceleartion ANSWER :b

Discussion

8.	If lambdadenotes the ratio of two specific heats of a gas, the ratio of slopes of adiabatic and isothermal PV curves at theirpoint of intersection is
Answer» `1//LAMBDA` `lambda` `lambda-1` `lambda+1` ANSWER :B

Discussion

9.	For water mu=4//3 and the velocity of light in vaccum is 3 times 10^8 ms^-1 the timetaken for light to travel a distance of 450m in water will be (nearly)
Answer» `1.5 mu s` `1 mu s` `2 mu s` `3 mu s` Answer :C

Discussion

10.	A uniform circular disc of radicu R lies in the XY - plane with its centre at the orgin of co-ordinate system. Its moment of inertia about an axis, lying in the xy-plane, parallel to the x-axis and passing through a point on the y-axis at a distance y = 2R is I_(1). Its moment of inertia about an axis lying in a plane perpendicular to xy-plane passing through a point on the x-axis at a distance x = d is I_(2). If I_(1)=I_(2), the value of .d. is
Answer» `(SQRT(19))/(2)R` `(sqrt(17))/(2)R` `(sqrt(15))/(2)R` `(sqrt(13))/(2)R` Answer :C

Discussion

11.	A block of mass 5kg is lying on a rough horizontal surface. The coefficient of static and kinetic friction are 0.3 and 0.1 and g=10 ms^(-2). If a horizontal force of 50 N is applied on the block, the frictional force is
Answer» 25 N 5 N 10 N Zero Answer :B

Discussion

12.	What kind of motion is described by the equation s = s_(0) + ut + (1) /(2)at^(2)?
Answer» Solution :The equation DESCRIBES the linear motion of a particle with a constant ACCELERATION a the initial DISPLACEMENT and velocity being `s_(0)` and U, respectively.

Discussion

13.	A grindstone has a moment of inertia of 6 kg m^(2). A constant torque is applied and the grindstone is found to have a speed of 150 rpm, 10 seconds after starting from rest. The torque is
Answer» SOLUTION :`tau=lalpha = L omega//t = 600 xx 2PI xx 2.5//10 = 942 Nm`

Discussion

14.	If a body of mass 36 gm moves with SHM of amplitude A=13cm and period T=12 sec. At a time t=0 the displacement isd x=+13cm. The shortest time of passage from x=+6.5cm to x=-6.5 is
Answer» 4 sec 2 sec 6 sec 3 sec Answer :B

Discussion

15.	Deduce Boyle's law based on kinetic theory.
Answer» Solution :Boyle's law: From equation `P=(2)/(3)(U)/(V)=(2)/(3)u`, we know that `PV=(2)/(3)U` But the internal energy of an IDEAL gas is equal to N TIMES the average kinetic energy `(in)` of each MOLECULE `U=Nin` For a fixed TEMPERATURE, the average translational kinetic energy `in` will remain CONSTANT. It implies that `PV=(2)/(3)Nin` Thus PV = constant Therefore, pressure of a given gas is inversely proportional to its volume provided the temperature remains constant. This is Boyle's law.

Discussion

16.	When a ideal gas with pressure P and volume V is compressed isothermally to one fourth of its volume, the pressure is P_(1). When the same gas is compressed polytropically according to the equation PV^(1.5) = constant to one fourth of its initial volume, the pressure is P_(2). THe ratio (P_(1))/(P_(2)) is
Answer» `(1)/(2)` `(1)/(2^(1.5))` 2 `2^(1.5)` Solution :For a ISOTHERMAL PROCESS, PV = constant `:. PV = P_(1) (V)/(4)` or `P_(1) = 4P` For the polytropic process, `PV^(1.5)`= constant `:. PV^(1.5) = P_(2)((V)/(4))^(1.5)` or `P_(2) = (2^(2))^(3//2)P = 8P :. (P_(1))/(P_(2)) = (1)/(2)`

Discussion

17.	A person rides a bike with a constant velocity vecvwith respect to ground and another biker accelerates with acceleration ā with respect to ground. Who can apply Newton's second law with respect to a stationary observer on the ground?
Answer» SOLUTION :Second biker cannot apply Newton.s second law, because he is moving with ACCELERATION `veca` with respect to EARTH (he is not in inertial frame). But the first biker can apply Newton.s second law because he is moving at CONSTANT VELOCITY with respect to Earth (he is in inertial frame).

Discussion

18.	The total kinetic energy of translatory motion of all the molecules of 5 litres of nitrogen exerting a pressure P is 3000 J.
Answer» the TOTAL k.e of 10 litres of `N_2` at a pressure of 2P is 3000 J the total k.e of 10 literes of He at a pressure of 2P is 3000 J the total k.e of 10 litres of `O_2` at a pressure of 2P is 20000 J Solution :`U = (nfRT)/(2)`

Discussion

19.	Referring to the above two questions, the acceleration due to gravity is given by
Answer» `10 m//sec^(2)` `5m//sec^(2)` `20m//sec^(2)` `2.5 m//sec^(2)` ANSWER :A

Discussion

20.	If vecA=3hat(i)+4hat(j) and vecB=7hat(i)+24hat(j), find a vector having the same magnitude as vecB and parallel to vecA
Answer» Solution :The vector parallel to `vecA` and having magnitude of `vecB` is `vecC=\|vecB\|(vecA)/(\|vecA\|) = \|vecB\|HATA ""B=sqrt(7^(2)+24^(2))=25` and `hatA=(vecA)/(A)=(3hat(i)+4hat(j))/(sqrt(3^(2)+4^(2)))=(1)/(5)(3hat(i)+4hat(j))` `vecC=25xx(1)/(5)(3hat(i)+4hat(j)) = 15 hat(i)+20hat(j)`

Discussion

21.	In an experiment, the same time period is recorded if a bar pendulum is suspended at distances 12 cm, 24 cm, 40 cm and 52 cm respectively from its end. The length of bar pendulum is
Answer» 84 CM 72 cm 64 cm 60 cm Answer :C

Discussion

22.	The equation of simple harmonic is as following y(t) = 10 sin (20t+ 45^(@)). Find the amplitude of SHM.
Answer» `a= 30` `a= 20` `a= 10` `a=5` SOLUTION :`a= 10`

Discussion

23.	What is meant by compliance?
Answer» SOLUTION :The RECIPROCAL of STIFFNESS CONSTANT is CALLED complieance .

Discussion

24.	A flat-bottom kettle placed on a stove is being used to boil water and the thermal conductivity of the material is 0.5 cal s^(-1) cm^(-1). If the amount of steam being produced in the kettle is at rate 10 g min^(-1), calculate the difference of temperature between the inner and outer surface of of the bottom. the latent heat of steam is 540 cal g^(-1)
Answer» ANSWER :`0.2^(@)C`

Discussion

25.	A drop of water of surface area A and radius R at a temperature T breaks into two drops of area A_1 and A_2 , radii r_1and r_2and having temperatures T_1and T_2 Then the incorrect statement is
Answer» `A =A_1 +A_2` `T=T_1 +T_2` `R=r_1 +r_2` `A LT(A_1 +A_2)` ANSWER :A::B::C

Discussion

26.	The elastic collision between two bodies, A and B, can be cosidered using the following model. A and B are free to move along a common line without friction. When their distance is greater than d = 1 m, the interacting force is zero , when their distance is less d, a constant repulsive force F = 6 N is present. The mass of body A is m_(A) = 1 kg and it is initially at rest, the mass of body B is m_(B) = 3 kg and it is approaching body A head-on with a speed v_(0) = 2 m//s. Find th eminimum distance between A and B :-
Answer» <P>`0.25 m` `0.50 m` `0.75 m` `1 m` Solution :`F_(ext) = 0` on system containing A & B `vec(P)` is conserved At minimum seperation both will MOVE with same velocity `P_(1) = P_(f)` `2 XX 3 = 3 xx v` `v = (3)/(2)` `W_(all) = DeltaKE` `W_(F) = DeltaKE` `-6x = (1)/(2) xx 3 xx 2^(2) - (1)/(2) xx 4 xx ((3)/(2))^(2)` `x = 0.25` Minimum separation `= d - x = 1 - 0.25 = 0.75`

Discussion

27.	Calculate the accelerations of the pulleys B and C and the tension in the string passing over the pulley A of the figureFigure 5.22.
Answer» ANSWER :`g//11`,12.46 KGF

Discussion

28.	A small cube (mass = m ) is on the inner curved surface of a funnel rotating about its own axis. Its wall inclines at an angle theta with the horizontal. The cube is kept at a distance r from the vertical axis of rotation of the funnel. If the coefficient of friction between the funnel and the cube is mu, for what frequency of rotation of the funnel, will the cube remain at rest on the surface of the funnel? It is implied that the cube will roll down if the funnel remains stationary.
Answer» Answer :`(1)/(2PI) SQRT((g(SIN theta PM mu con theta))/(R(cos theta pm mu sin theta)))`

Discussion

29.	Give examples of a one-dimensional motion where (a) The particle moving along positive x-direction comes to rest periodically and moves forward.(b) The particle moving along positive x-direction comes to rest periodically and moves backward.
Answer» SOLUTION :When we are writing an equation BELONGING to periodic nature it include SINE or cosine function. (a) The particle will be moveing along positive X-direction only if `x(t) =1 - sin t` Velocity `v (t) = (dx(t))/(dt) =1 - cos t` Acceleration `a (t) = (dv)/(dt) = sin t ` When `t =0, x (t) =0` When `t = pi , x (t) = pi gt 0` When `t =0, x (t) = 2pi gt 0` (b) Equation can be represented by `x (t) = sin t ` `therefore v = (d)/(dt) x (t) = cos t ` As DISPLACEMENT and velocity includes sin t and cos t hence these equations represent periodic.

Discussion

30.	Aeroplanes are streamlined to reduce
Answer» FLUID friction SLIDING friction KINETIC friction LIMITING friction Answer :A

Discussion

31.	Two bodies of masses m_(1) and (m_(2) are separated by certain distance . IfvecF_(12) is the force on m_(1) due to m_(2) and vecF_(12)is the force on m_(2) due to m_(1) , then
Answer» `F_(12) = F_(21)` `vecF_(12) = vecF_(21)` `vecF_(12) = -vecF_(21)` both a & c Answer :D

Discussion

32.	A student measured the diameter of a wire using a screw gauge with the least count 0.001 cm and listed the measurements. The measures value should be recorded as:
Answer» `5.320` CM `5.3` cm `5.32` cm `5.3200` cm Answer :A

Discussion

33.	The loss in weight of a solid when immersed in a liquid at 0^(@) C in w_(0) and t°C is 'w'. If cubical coefficient of expansion of the solid and the liquid are gamma_(s) and gamma_(t) then 'w'=
Answer» `w_(0) [1+ ( gamma_(s) - gamma_(l)) t ]` `w_(0) [ 1- ( gamma_(s) - gamma_(l)) t ]` ` w_(0) [ ( gamma_(s) - gamma_(l)) t ]` `( w_(0) t) /( [ gamma_(s) - gamma_(l) ]) ` ANSWER :A

Discussion

34.	The maximum displacement of an osicalliting particle is 0.05 m. If its time period is 1.57 s (i) What is the velocity at the mean positon? (ii) What is its acceleration at the exreme position?
Answer» `0.2ms^(-1),0.2ms^(-2)` `0.8ms^(-1),0.8ms^(-2)` `0.2ms^(-1),0.8ms^(-2)` `0.8ms^(-1),0.2ms^(-2)` ANSWER :C

Discussion

35.	A thin horizontal circular disc is rotating about a vertical axis passing through its centre. An insect is at rest at a point near the rim of the disc. The insect now moves along the diameter of the disc to reach its other end. During the journey of the insect. The angular speed of the disc:
Answer» REMAINS unchanged continuously decreases continuously increases first increased Answer :D

Discussion

36.	The force which always opposes the relative motion between an object and the surface where it is placed is
Answer» CONCURRENT FORCE FRICTIONAL force IMPULSIVE force coplanar force SOLUTION : frictional force

Discussion

37.	{:(,"SECTION-A",,"SECTION-B"),("a)","Incompressible liquid","e)","Density constant"),("b)","Turbulent flow","f)","Stream lines"),("c)","Tube of flow","g)","Constant"),("d)","Fluid flux rate in laminar flow","h)","Reynold's no."gt2000):}
Answer» a-f, B-e, c-g, d-h a-e, b-h, c-f, d-g a-g, b-f, c-e, d-h a-h, b-g, c-e, d-f Answer :B

Discussion

38.	A body is projected with a velocity 60 ms^(-1) at 30^(0) to horizontal. Its intial velocity vecotr is
Answer» `10hat(i)+10sqrt(3)HAT(J)` `30hat(i)+30sqrt(3)hat(j)` `30sqrt(3)hat(i)+30hat(j)` `30sqrt(3)hat(i)` ANSWER :C

Discussion

39.	The cylindrical tube of a spray pump has a cross -section of 8.0cm^(2) one end of which has 40 fine holes each ofdiameter 1.0mm . If the liquid flow inside the tube is 1.5mmin^(-1) , what is the speed of ejection of the liquid through the holes ?
Answer» SOLUTION :CROSS section area of pipe `A_(1)=8xx10^(-4)m^(2)` and speed `v_(1)=(1.5)/(60)ms^(-1)=0.025ms^(-1)` Area of holes at the end of other tube =40 `therefore` Area of cross section at other end , `A_(2)=40A` `=40pixx25xx10^(-8)m^(2)`and the speed of liquid at other end `v_(2)`=? From equation of CONTINUITY , `A_(1)v_(1)=A_(2)v_(2)` `8xx10^(-4)xx0.025=40xx3.14xx25xx10^(-8)xxv_(2)` `thereforev_(2)=(8xx10^(-4)xx0.025)/(40xx3.14xx25xx10^(-8))` `=0.00006369xx10^(-8)``=0.00006369xx10^(-4)` `thereforev_(2)=0.64ms^(-1)`

Discussion

40.	A body of mass 8kg is in limiting equi'ibrium over an inclined plane of inclination 30^(@. If the inclination is made 60^(@), the minimum force required to prevent the body from sliding down is (g = 10 ms ^(-2))
Answer» 80 N `(80)/(SQRT3) N` `(40 N)/(sqrt3)` `40 sqrt3 N` Answer :B

Discussion

41.	A block is pushed up a rough inclined plane of 45^(@). If the time of descent is three times the time of ascent, the coefficient of friction is
Answer» `0.6` `0.4` `0.8` `0.25` ANSWER :C

Discussion

42.	State the names of two substances which contract on heating?
Answer» SOLUTION :RUBBER, PLASTIC

Discussion

43.	A rod, when heated from 0^(@)C to 50^(@)C, expands by 1.0 mm. Another rod, twice as long as the first at 0^(@)C and of the same material, is heated from 0^(@)C to 25^(@)C. The second rod will expand by …………….. .
Answer» 0.5 mm 1.0 mm 2.0 mm 4.0 mm Solution :`Deltal=l_(0)alphaDeltat` `(Deltal_(2))/(Deltal_(1))=(2l_(o)Deltat_(2))/(l_(o)Deltat_(1))RARR (2xx25)/(50)xx1.0 rArr Deltal_(2)=1.0` mm

Discussion

44.	A spring balance has a scale that reads from 0 to 50 kg. The length of the scale is 20 cm. A body suspended from this spring, when displaced and released oscillates with period of 0.60 s. What is the weight of the body?
Answer» SOLUTION :Here `m=50kg,` MAX extension `y=20-0=20cm=0.2m,T=0.6s` max FORCE `F=mg=50xx9.8N` `:.k=F/u=(50xx9.8)/0.2=2450Nm^(-1)` there As `T=2pisqrt(m/k),m=(T^(2)k)/(4pi^(2))=((0.6)^(2)xx2450)/(4xx(3.14)^(2))=22.35kg` `:.` Weight of BODY `=mg=22.35xx9.8=219.1N`

Discussion

45.	The centre of gravity of a body on the earth coincides with its centre of mass for a small object whereas for an extended object it may not. What is the qualitative meaning of small and extended in this regard? For which of the following two coincides? A building, a pond, a lake, a mountain?
Answer» SOLUTION :If the vertical height of the object is very small as compared to the earth.s RADIUS, it is CALLED OBEJCT small, else it is extended. (1) Building and pond are small objects. (2) A deep lake and a mountain are examples of extended objects.

Discussion

46.	An engine of one metric ton is going up an inclined plane, 1 in 2 at the rate of 36 kmph. If the co-efficient of friction is 1//sqrt(3), the power of engine is
Answer» 9.8 W 98 W 980 W 98 KW ANSWER :D

Discussion

47.	A cylindrical vessel contains a liquid of density rho upto a height h. The liquid is closed by a piston of mass mand area of cross section A. There is a small hole at the biottom of the vessel. Find the speed v with which the liquid comes of out of the hole.
Answer» Solution :Applying Bernouylli.s THEOREM at 1 and 2 difference in pressure ENERGY between 1 and 2= difference in kinetic energy betwee 1 and 2 or `rhogh+(mg)/A=1/2 rho v^(2)` or `v=sqrt(2gh+(2MG)/(rhoA))=sqrt(2(gh+(mg)/(rhoA)))`

Discussion

48.	A hose pipe lying on the ground shoots a stream of water upward at an angle 60^(@) to the horizontal at a speed of 20 ms^(-1). The water strikes a wall 20m at a height of (g = 10ms^(-2))
Answer» 14.64 m 7.32 m 29.28 m 10 m Answer :A

Discussion

49.	The phase difference between velocity and displacement of simple harmonic oscillator
Answer» `PI` `(pi)/2` `(pi)/4` `(pi)/4` ANSWER :B

Discussion

50.	show that when reflection takes place from a boundary separating two media and the velocity in the second medium is infinitely large , the amplitude of the reflected wave is equal to the amplitude of the incident wave and there is a phase change of pi in the displacement wave.
Answer» Solution :Suppose a progressive wave of amplitudde `a` is travelling with SPEED `c` from left to right and there is a RIGID wall at ` x = 0 `. Then `y_(1) = a sin omega ( t - (x)/(c ))` is the equation of the incident wave Let `a'` be the amplitude of the reflected wave . Then ` y _(2) = a' sin omega ( t + ( x)/(c ))` is the equation of the reflected wave . By the principle of the superposition ` y = y_(1) + y_(2)` or `y = a sin omega ( t - ( x)/( c)) + a' sin omega ( t + (x)/( c))` Since the wall is rigid , at ` x = 0 , y = 0 , for all t` `:. 0 = a sin omega t + a' sin omega t = ( a + a') sin omega t` `because sin omega t != 0, a + a' = 0 or a = -a'` The negative sign shows that there is a phase change by `PI` in the displacement wave.

Discussion

Explore topic-wise InterviewSolutions in Current Affairs.

A solid sphere of mass M and radius R having moment of inertia about an axis passing through the centre of mass as I, is recast into a disc of thickness I, whose moment of inertia about an axis passing through its edge and perpendicular to its plane remains I. Then, radius of the disc will be

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{:(,"SECTION-A",,"SECTION-B"),("a)","Incompressible liquid","e)","Density constant"),("b)","Turbulent flow","f)","Stream lines"),("c)","Tube of flow","g)","Constant"),("d)","Fluid flux rate in laminar flow","h)","Reynold's no."gt2000):}

A body is projected with a velocity 60 ms^(-1) at 30^(0) to horizontal. Its intial velocity vecotr is

The cylindrical tube of a spray pump has a cross -section of 8.0cm^(2) one end of which has 40 fine holes each ofdiameter 1.0mm . If the liquid flow inside the tube is 1.5mmin^(-1) , what is the speed of ejection of the liquid through the holes ?

A body of mass 8kg is in limiting equi'ibrium over an inclined plane of inclination 30^(@. If the inclination is made 60^(@), the minimum force required to prevent the body from sliding down is (g = 10 ms ^(-2))

A block is pushed up a rough inclined plane of 45^(@). If the time of descent is three times the time of ascent, the coefficient of friction is

State the names of two substances which contract on heating?

A rod, when heated from 0^(@)C to 50^(@)C, expands by 1.0 mm. Another rod, twice as long as the first at 0^(@)C and of the same material, is heated from 0^(@)C to 25^(@)C. The second rod will expand by …………….. .

A spring balance has a scale that reads from 0 to 50 kg. The length of the scale is 20 cm. A body suspended from this spring, when displaced and released oscillates with period of 0.60 s. What is the weight of the body?

The centre of gravity of a body on the earth coincides with its centre of mass for a small object whereas for an extended object it may not. What is the qualitative meaning of small and extended in this regard? For which of the following two coincides? A building, a pond, a lake, a mountain?

An engine of one metric ton is going up an inclined plane, 1 in 2 at the rate of 36 kmph. If the co-efficient of friction is 1//sqrt(3), the power of engine is

A cylindrical vessel contains a liquid of density rho upto a height h. The liquid is closed by a piston of mass mand area of cross section A. There is a small hole at the biottom of the vessel. Find the speed v with which the liquid comes of out of the hole.

A hose pipe lying on the ground shoots a stream of water upward at an angle 60^(@) to the horizontal at a speed of 20 ms^(-1). The water strikes a wall 20m at a height of (g = 10ms^(-2))

The phase difference between velocity and displacement of simple harmonic oscillator

show that when reflection takes place from a boundary separating two media and the velocity in the second medium is infinitely large , the amplitude of the reflected wave is equal to the amplitude of the incident wave and there is a phase change of pi in the displacement wave.