40048 + Interview Questions in Physics in Class 11

1.	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
Answer» `R//2 SQRT(3)` R/2 `sqrt(3)R//2` `R//sqrt(3)` ANSWER :D

Discussion

2.	Type of satellites are given in Column-I and their uses are given in Column-II. Match them properly : {:("Column-I","Column-II"),("(1) Polar satellite","(a) Tele communication"),("(2) Geo-stationary satellite","(b) Investigation"),(,"(c) For information about atmosphere"):}
Answer» ANSWER :(1-b), (2-a)

Discussion

3.	A force of 100 dynes acts on a particle of mass 0.5 kg for 10 sec. Calculate the velocity of the particle and the K.E produced.
Answer» SOLUTION :20cm/s,`10^5`ERGS

Discussion

4.	A wave stretched between two rigid supports vibrate in its fundamental mode with a frequency of 45 Hz. The mass of wire is3.5 xx 10^(-2) kg and its linear mass density is 4.0 xx 10^(-2) kg m^(-1). What is (a) the speed of transverse wave on the string, and (b) the tension in the string?
Answer» SOLUTION :(a) `79 MS^(-1)` (b) `248N`

Discussion

5.	A cappilary of diameter d mm is dipped in water such that the water rises to a height of 30 mm. If the radius of the capillary is made ((2)/(3)) of its previous value, then compute the height up to which water will rise in the new capillary ?
Answer» Solution :We KNOW the height of the CAPILLARY RISE `H = (2T cos theta)/(r dg)` where T = surface tension, r = RADIUS , d = density , g = acceleration due to gavity Now, `h_1r_1 = h_2r_2implies (h_2)/(h_1) = (r_1)/(r_2)` Here , `r_2 = 2/3 r_1 and h_1 = 30 mm` `h_2 = (r_1)/((2/3)r_1) xx 30 = 3/2 xx 30` `h_2 = 45 mm`.

Discussion

6.	Choose the correct statement from the following statement ?
Answer» The DOT product is associative The dot product is commutative The dot product is not commutative The dot product is applied only to UNIT vectors . Answer :B

Discussion

7.	(A) : In taking into account the fact that any object which floats must have an average density less than that of water, during world war 1, a number of cargo vessels are made of concrete. (R ) : Concrete cargo vessels filled with air floats on water.
Answer» Both (A) and (R ) are TRUE and (R ) is the correct EXPLANATION of (A) Both (A) and (R ) are true and (R ) is not the correct explanation of (A) (A) is true but (R ) is FALSE Both (A) and (R ) are false ANSWER :A

Discussion

8.	A oscillator of mass 100g executes damped oscillation. When it complete 100 oscillations its amplitude of oscillation becomes half to its original amplitude. If time period is 2s, then find the value of damping coefficient.
Answer» SOLUTION :`B= 0.693" DYNE SECOND/"CM`

Discussion

9.	At two particular closest instants of time t_(1)and t_(2)the displacements of a particle performing SHM are equal. At these instants.
Answer» INSTANTANEOUS SPEEDS are equal. instantaneous ACCELERATION are equal. phases of the MOTION are unequal. all of the above Answer :D

Discussion

10.	The escape velocity of the surface of earth is 11.2 km/s. What would be the escape velocity of the surface of another planet of the samemass but (1^(th))/4 times the radius of the earth ?
Answer» 44.8 km/s 22.4 km/s 5.6 km/s 11.2 km/s Solution :`implies` For surface of earth. `v_e=SQRT((2GM_e)/R_e)= 11.2 (km)/s` For PLANET `v_p = (sqrt(2GM_p))/R_p` mass of planet `M_p=M_e` Radius of planet `R_p = R_e/4` `v_p = sqrt((2GM_e)/(R_e/4)) ` `=2 sqrt((2GM_e)/R_e)` `=2(v_e)` `= 1 (11.2 km//s) ` ` =22.4km//s `

Discussion

11.	A man running has half the kinetic energy of a boy of half his mass. The man speeds up by 1 ms^(-1) and then has KE as that of the boy. What was the original speed of man?
Answer» `sqrt(2) ms^(-1)` `(sqrt(2)-1) ms^(-1)` `(sqrt(2) +1) ms^(-1)` None of these Answer :C

Discussion

12.	What is the displacement of a body in SHM when the potential energy becomes three times than kinetic energy?
Answer» Solution :`(1)/(3)U =K` `(1)/(3) (kx^(2))/(2) = (1)/(2)k(A^(2)-x^(2))` `therefore x^(2) = 3A^(2) -3x^(2)` `therefore 4x^(2) = 3A^(2)` `therefore x^(2)=(3A^2)/(4)` `therefore x = pm (SQRT(3)A)/(sqrt(2))`.

Discussion

13.	If for a gas R/(C_v)=0.67, this gas is made up of molecules which are
Answer» monoatomic DIATOMIC POLYATOMIC mixture of diatomic and polyatomic molecules Answer :A

Discussion

14.	A body weights w_(1) in air and w_(2) in water. The specific gravity of the material of the body is
Answer» `(W_(1))/(W_(2))` `(W_(1)-W_(2))/(W_(1))` `(W_(1)-W_(2))/(W_(2))` `(W_(1))/(W_(1)-W_(2))` ANSWER :D

Discussion

15.	A and B are the numerical values of a physical quantity and C and D are its units in two systems of mesurement . If C > D, then
Answer» `A GT B` `A LT B` A= B A & B cannot be related Answer :B

Discussion

16.	A pendulum has a string of length 99.39 cm. how much length of the pendulum must be shortened to keep the current time of the pendulum if it loses 4 s a day?
Answer» 0.0009 cm 0.009 cm 0.09 cm 0.9 cm Solution :Time lost by PENDULUM per day=4s, dn=-4s NUMBER of seconds in a day, n=`24xx3600s` LET dl be the length by which the pendulum should be SHORTENED to keep the correct time `(dn)/(n)=-(dl)/(2l)implies(-4)/(24xx3600)=(-dl)/(2xx99.39)` `impliesdl=0.00920cm`

Discussion

17.	Hydrostatic pressure is a scalar quantity, even though pressure is force divided by area and force is a vector? Why?
Answer» SOLUTION :For a QUANTITY to be vector, it should have magnitude and DIRECTION. Pressure does not DEPEND on direction, so it is a SCALAR.

Discussion

18.	A black body at a high temperature T radiates energy at the rate of E. When the temperature falls to T/2,the radiated energy will be
Answer» E/4 E/2 2E E/16 Answer :D

Discussion

19.	Angular momentum is ………………….. Vector.
Answer» `vecpxx VECR` `vecrxx VECP` `(vecr)/(vecp)` `vecr.vecp` ANSWER :B

Discussion

20.	Only …. Waves can be propagated by fluid medium.
Answer» SOLUTION :LONGITUDINAL.

Discussion

21.	The Poisson's ratio o should satisfy the relation
Answer» `-1 LT SIGMA lt 0.5` `-0.5 lt sigma lt 1` `0.5 lt sigma lt 1` `-1 lt sigma lt -0.5` ANSWER :A

Discussion

22.	What is GUT ?
Answer» Solution :GUT MEANS GRAND UNIFICATION THEORY which COMBINES all forces into a single force.

Discussion

23.	Red shift means
Answer» SOURCE is going away from observer Source is COMING TOWARDS observer There is no relative motion between observer & source NONE of these Answer :A

Discussion

24.	At a certain height a body at rest exlpoles into two equal fragements with one fragment receiving a horizontal velocity of 10 ms^(-1). The time interval after the exlosion for which the velocity vectors of the two frgaments become perpendicular to each other is (g = 10ms^(-2))
Answer» 1s 2 s 1.5 s 1. 75 s Answer :A

Discussion

25.	The P.E of a string when stretched by 2 cm is U.Its P.E when stretched by 10 cm is
Answer» U/25 U/5 5U 25U Answer :D

Discussion

26.	The cross product of the vectors (2i+3j+4k) and (i+4j-5k)is
Answer» `-hati-14hatj+11hatk` `hati-14hatj+11hatk` `-hati+14hatj+11hatk` `-hati+14hatj+5hatk` ANSWER :C

Discussion

27.	The height and width of each step of a staircase are 20 cm and 30 cm respectively. A ball rolls off the top of a stair with horizontal velocity v and hits the fifth step. The magnitude of v is (g = 10 ms^(-2))
Answer» `1.5 SQRT(5) MS^(-1)` `3sqrt(5) ms^(-1)` `7.5 ms^(-1)` `1.5 ms^(-1)` ANSWER :A

Discussion

28.	The bob A of a pendulum of length 1m released from 30^(@) to the vertical hits another bob B of same mass at rest on the table. How high does the bob A rise after the collision and find the velocity of B.
Answer» Solution :The bob of pendulum acquires a velocity `V= sqrt(2gl(1- cos THETA))`, on REACHING the lower most POSITION and makes elastic collision with the bob B of same mass. Hence the bodies simply EXCHANGE their velocities after collision. The bob of pendulum does not RISE at all and velocity of B is `V= sqrt(2gl(1- cos theta))= 1.62 ms^(-1)`

Discussion

29.	The angular speed of a motor wheel is increased from 600 rpm to 1560 rpm in 8 seconds. (i) What is its angular acceleration, assuming the acceleration to be uniform? (ii) How many revolutions does the engine make during this time?
Answer» SOLUTION :`alpha=4pi" RADS"^(-1)andn=144`

Discussion

30.	What are personal errors ?
Answer» SOLUTION :These are the ERRORS which ARISE DUE to the inexperience of the observer.

Discussion

31.	The dimensional formula ML^(2) T^(-2) represents
Answer» MOMENT of a force Force Acceleration Momentum Answer :A

Discussion

32.	A Fahrenheat thermonmeter reads 113^(@)F while a faulty celsius thermometer reads 44^(@)C. The correction to be applied to the celsius thermometer is
Answer» ANSWER :`+1^@C`

Discussion

33.	Shape of the earth is not perfect spherical. How we can say ?
Answer» Solution :`IMPLIES` Because on the earth SURFACE value of .g. is foundto be different at different places. As `g = (GM_e)/(R_e^2)`g is different means RADIUS of earth R, is not same at all places on the earth.

Discussion

34.	A body of mass m is taken from the Earth's surface to a height equal to the radius R of the earth. If g is the acceleration to gravity at the surface of the Earth, then find the change in the potential energy of the body .......
Answer» `1/4mgR` `1/2`MGR mgR 2mgR Solution :CHANGEIN P.E `= (-GMM)/(R+R) -(-(GMm)/R)=(GMm)/(2R) = 1/2 mgR`

Discussion

35.	For object at rest on any planet, its escape speed v_e is directly proportional to its mass and radius.
Answer» Answer :False, it is directly proportional to square ROOT of mass and RADIUS. `[:'v_e=sqrt(-(2GM)/R)]`

Discussion

36.	A gas is enclosed in a vessel of volume V at a pressure P. It is being pumped out of the vessel by means of a piston - pump with a stroke volume v. What is the final pressure in the vessel after n strokes of the pump? (Assume temperature remains constant).
Answer» `P [ (1)/( 1- ( UPSILON//V) )]^(1//N)` `P [ (1)/( 1+ ( upsilon//V) )]` `P ( 1+ ( upsilon)/( V) )` `(( 1+ (upsilon)/( V) )^(n) )/(P)` ANSWER :B

Discussion

37.	A body of mass m resting on a smooth horizontal plane starts moving under a constant force F. During its rectilinear motion, the angle theta between the direction of force and horizontal plane varies as 8 = kx , where k is a constant and x is the distance travelled by the body from the initial position. What is the velocity of the body?
Answer» `(2F)/m tan theta` `SQRT((2Fsin theta)/(mK)` `sqrt((Fcos theta)/(mk))` `sqrt((2Fcos theta)/(mk)` ANSWER :B

Discussion

38.	Some quantity of heat is given to a substance. The quantity which determines the temperature of the body is
Answer» Mass specific heat Water EQUIVALENT THERMAL conductivity Answer :C

Discussion

39.	A force of 3N and 4N are acting perpendicular to an object, the resultant force is
Answer» 9N 16N 5N 7N

Discussion

40.	When a projectile attains the escape velocity, then on surface of planet its
Answer» KE is GREATER than PE numarically PE is greater than KE NUMERICALLY Both PE and KE are numerically equa none Answer :C

Discussion

41.	What is the density of water at a depth where pressure is 80.0 atm, given that its density at the surface is 1.03xx103" kg m"^(-3) ?
Answer» ANSWER :`1.034xx10^(3)" Kg/m"^(3)`

Discussion

42.	In ________ the translational motion is more than rotational motion.
Answer» Slipping frictional motion Circular motion Sliding Answer :d

Discussion

43.	Two seconds after projection, a projectile is moving at 30^(@) above the horizontal . After one more second it is moving horizontally. If g=10ms^(-2), the velocity of projection is
Answer» `10 SQRT(3) ms^(-1)` 20 m/s 10 m/s `20 sqrt(3)` m/s Answer :D

Discussion

44.	N molecules each of mass m of gas A and 2N molecules each of mass 2m of gas B are contained in the same vessel at temperature T. The mean square of the velocity of molecules of gas B is v^2 and the mean square of x component of the velocity of molecules of gas A is w^2. The ratio (w^2)/( v^2) is
Answer» `1` `2` `1/3` `2/3` ANSWER :D

Discussion

45.	A copper wire of negligible mass, length (l), cross-sectional area (A) is kept on a smooth horizontal table with one end fired, a ball of mass 'm' is attached at other end. The wire and the ball are rotated with angular velocity 'omega'. If wire elongates by Delta lthen find Young's modulus of wire. If on increasing the angular velocity from omegato omega^1 the wire breakdown, obtain breaking stress (Delta l lt lt l)
Answer» Solution :a)`R = L + Delta l` ` F = T mr w^2 = m (l+Delta l)omega^2 ` as `Delta l` in small ` F = ml omega^2 "" y = (Fl)/(Ae)"" y = ((ml omega^2)l)/(A Delta l)` B) we know breaking stress= breaking force/area of cross SECTION ` = (ml omega^(1^2) )/(A)`

Discussion

46.	When a source of sound approaches a stationary listener, the sound appears to be ______to the listener . (Fill in the blank)
Answer» SOLUTION :N/A

Discussion

47.	1gm water at 100^@C and 10^(5)Papressure converts into 1841cm^3 of steam at constant temperature and pressure. If latent heat of vaporization of water is 2250J/g. The change in internal energy of water in this process is
Answer» zero 2250J 2066J none ANSWER :C

Discussion

48.	The equation of a certain gas can be written as (T^(7//5))/(P^(2//5)) const.. Its specific heat at constant volume will be
Answer» `3/2 R` `5/2 R` `7/2R` `2R` ANSWER :B

Discussion

49.	If the coefficient of apparent expansion of the liquid is greater than the coefficient of real expansion of the liquid, what do you infer?
Answer» Solution :We know `gamma _(g) = gamma _(s) + gamma_("essel")If gamma _(s)gtgamma _(R ) gt gamma _(s)`the COEFFICIENT of volume EXPANSION of the VESSEL MUST be negative. I.e., the material of the vessel contracts on heating.

Discussion

50.	A tangentialforce of 2100 N is appliedon a surfaceof area 3xx10^(-6)m^(2) which is0.1 m from a fixed face. The force producesa shift of 7 mm of upper surface with respectto bottom. Calculatethe modulusof rigidity of the material.
Answer» Solution :`F=2100N, A=3XX10^(-6) m^(2)`, `L=0.1m, DELTAX=7xx10^(-3)m`. `G=(FL)/( A Deltax)=(2100xx0.1)/(3xx10^(-6)xx7xx10^(-3))=1xx10^(10)NM^(-2)`

Discussion

Explore topic-wise InterviewSolutions in Current Affairs.

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

Type of satellites are given in Column-I and their uses are given in Column-II. Match them properly : {:("Column-I","Column-II"),("(1) Polar satellite","(a) Tele communication"),("(2) Geo-stationary satellite","(b) Investigation"),(,"(c) For information about atmosphere"):}

A force of 100 dynes acts on a particle of mass 0.5 kg for 10 sec. Calculate the velocity of the particle and the K.E produced.

A wave stretched between two rigid supports vibrate in its fundamental mode with a frequency of 45 Hz. The mass of wire is3.5 xx 10^(-2) kg and its linear mass density is 4.0 xx 10^(-2) kg m^(-1). What is (a) the speed of transverse wave on the string, and (b) the tension in the string?

A cappilary of diameter d mm is dipped in water such that the water rises to a height of 30 mm. If the radius of the capillary is made ((2)/(3)) of its previous value, then compute the height up to which water will rise in the new capillary ?

Choose the correct statement from the following statement ?

(A) : In taking into account the fact that any object which floats must have an average density less than that of water, during world war 1, a number of cargo vessels are made of concrete. (R ) : Concrete cargo vessels filled with air floats on water.

A oscillator of mass 100g executes damped oscillation. When it complete 100 oscillations its amplitude of oscillation becomes half to its original amplitude. If time period is 2s, then find the value of damping coefficient.

At two particular closest instants of time t_(1)and t_(2)the displacements of a particle performing SHM are equal. At these instants.

The escape velocity of the surface of earth is 11.2 km/s. What would be the escape velocity of the surface of another planet of the samemass but (1^(th))/4 times the radius of the earth ?

A man running has half the kinetic energy of a boy of half his mass. The man speeds up by 1 ms^(-1) and then has KE as that of the boy. What was the original speed of man?

What is the displacement of a body in SHM when the potential energy becomes three times than kinetic energy?

If for a gas R/(C_v)=0.67, this gas is made up of molecules which are

A body weights w_(1) in air and w_(2) in water. The specific gravity of the material of the body is

A and B are the numerical values of a physical quantity and C and D are its units in two systems of mesurement . If C > D, then

A pendulum has a string of length 99.39 cm. how much length of the pendulum must be shortened to keep the current time of the pendulum if it loses 4 s a day?

Hydrostatic pressure is a scalar quantity, even though pressure is force divided by area and force is a vector? Why?

A black body at a high temperature T radiates energy at the rate of E. When the temperature falls to T/2,the radiated energy will be

Angular momentum is ………………….. Vector.

Only …. Waves can be propagated by fluid medium.

The Poisson's ratio o should satisfy the relation

What is GUT ?

Red shift means

At a certain height a body at rest exlpoles into two equal fragements with one fragment receiving a horizontal velocity of 10 ms^(-1). The time interval after the exlosion for which the velocity vectors of the two frgaments become perpendicular to each other is (g = 10ms^(-2))

The P.E of a string when stretched by 2 cm is U.Its P.E when stretched by 10 cm is

The cross product of the vectors (2i+3j+4k) and (i+4j-5k)is

The height and width of each step of a staircase are 20 cm and 30 cm respectively. A ball rolls off the top of a stair with horizontal velocity v and hits the fifth step. The magnitude of v is (g = 10 ms^(-2))

The bob A of a pendulum of length 1m released from 30^(@) to the vertical hits another bob B of same mass at rest on the table. How high does the bob A rise after the collision and find the velocity of B.

The angular speed of a motor wheel is increased from 600 rpm to 1560 rpm in 8 seconds. (i) What is its angular acceleration, assuming the acceleration to be uniform? (ii) How many revolutions does the engine make during this time?

What are personal errors ?

The dimensional formula ML^(2) T^(-2) represents

A Fahrenheat thermonmeter reads 113^(@)F while a faulty celsius thermometer reads 44^(@)C. The correction to be applied to the celsius thermometer is

Shape of the earth is not perfect spherical. How we can say ?

A body of mass m is taken from the Earth's surface to a height equal to the radius R of the earth. If g is the acceleration to gravity at the surface of the Earth, then find the change in the potential energy of the body .......

For object at rest on any planet, its escape speed v_e is directly proportional to its mass and radius.

A gas is enclosed in a vessel of volume V at a pressure P. It is being pumped out of the vessel by means of a piston - pump with a stroke volume v. What is the final pressure in the vessel after n strokes of the pump? (Assume temperature remains constant).

Some quantity of heat is given to a substance. The quantity which determines the temperature of the body is

A force of 3N and 4N are acting perpendicular to an object, the resultant force is

When a projectile attains the escape velocity, then on surface of planet its

What is the density of water at a depth where pressure is 80.0 atm, given that its density at the surface is 1.03xx103" kg m"^(-3) ?

In ________ the translational motion is more than rotational motion.

Two seconds after projection, a projectile is moving at 30^(@) above the horizontal . After one more second it is moving horizontally. If g=10ms^(-2), the velocity of projection is

N molecules each of mass m of gas A and 2N molecules each of mass 2m of gas B are contained in the same vessel at temperature T. The mean square of the velocity of molecules of gas B is v^2 and the mean square of x component of the velocity of molecules of gas A is w^2. The ratio (w^2)/( v^2) is

When a source of sound approaches a stationary listener, the sound appears to be ______to the listener . (Fill in the blank)

1gm water at 100^@C and 10^(5)Papressure converts into 1841cm^3 of steam at constant temperature and pressure. If latent heat of vaporization of water is 2250J/g. The change in internal energy of water in this process is

The equation of a certain gas can be written as (T^(7//5))/(P^(2//5)) const.. Its specific heat at constant volume will be

If the coefficient of apparent expansion of the liquid is greater than the coefficient of real expansion of the liquid, what do you infer?

A tangentialforce of 2100 N is appliedon a surfaceof area 3xx10^(-6)m^(2) which is0.1 m from a fixed face. The force producesa shift of 7 mm of upper surface with respectto bottom. Calculatethe modulusof rigidity of the material.