50278 + Interview Questions in Physics

1.	A thin ring of radius R is made of a material of density ρ and Young’s modulus Y. If the ring is rotated about its centre in its own plane with angular velocity ω and the small increase in its radius is ρω2R3λY, then find λ___
Answer» A thin ring of radius R is made of a material of density $ρ$ and Young’s modulus Y. If the ring is rotated about its centre in its own plane with angular velocity $ω$ and the small increase in its radius is $\frac{ρ ω^{2} R^{3}}{λ Y}$ , then find $λ$ ___

Discussion

2.	A parallel plate capacitor has capacitance C. When its area filled with a dielectric of dielectric constant k = 2, as shown in figure
Answer» A parallel plate capacitor has capacitance C. When its area filled with a dielectric of dielectric constant k = 2, as shown in figure

2.

A parallel plate capacitor has capacitance C. When its area filled with a dielectric of dielectric constant k = 2, as shown in figure

Answer»

A parallel plate capacitor has capacitance C. When its area filled with a dielectric of dielectric constant k = 2, as shown in figure

Discussion

3.	Two identical tuning forks vibrating at the same frequency 256 Hz are kept fixed at some distance apart. A listener runs between the forks at a speed of 3.0 m/s so that he approaches one tuning fork and recedes from the other (figure 16-E10). Find the beat frequency observed by the listener. Speed of sound in air = 332 m/s.
Answer» Two identical tuning forks vibrating at the same frequency 256 Hz are kept fixed at some distance apart. A listener runs between the forks at a speed of 3.0 m/s so that he approaches one tuning fork and recedes from the other (figure 16-E10). Find the beat frequency observed by the listener. Speed of sound in air = 332 m/s.

3.

Two identical tuning forks vibrating at the same frequency 256 Hz are kept fixed at some distance apart. A listener runs between the forks at a speed of 3.0 m/s so that he approaches one tuning fork and recedes from the other (figure 16-E10). Find the beat frequency observed by the listener. Speed of sound in air = 332 m/s.

Answer»

Two identical tuning forks vibrating at the same frequency 256 Hz are kept fixed at some distance apart. A listener runs between the forks at a speed of 3.0 m/s so that he approaches one tuning fork and recedes from the other (figure 16-E10). Find the beat frequency observed by the listener. Speed of sound in air = 332 m/s.

Discussion

4.	Two loudspeakers L1 and L2 driven by a common oscillator and amplifier, are arranged as shown. The frequency of the oscillator is gradually increased from zero and the detector at D records a series of maxima and minima. If the speed of sound is 330 ms–1 then the frequency at which the first maximum is observed is :
Answer» Two loudspeakers $L_{1}$ and $L_{2}$ driven by a common oscillator and amplifier, are arranged as shown. The frequency of the oscillator is gradually increased from zero and the detector at $D$ records a series of maxima and minima. If the speed of sound is $330 {ms}^{- 1}$ then the frequency at which the first maximum is observed is :

Discussion

5.	Speed of sound in air is 332 m/s at NTP. What will be the speed of sound in hydrogen at NTP if the density of hydrogen at NTP is (1/16) that of air?
Answer» Speed of sound in air is $332 m/s$ at NTP. What will be the speed of sound in hydrogen at NTP if the density of hydrogen at NTP is $(1 / 16)$ that of air?

Discussion

6.	A body of mass 2 kg is thrown vertically upwards with an initial speed of 10 m/s. The work done by the force of gravity during the time the body reaches its maximum height. (Consider g=10 m/s2)
Answer» A body of mass $2 kg$ is thrown vertically upwards with an initial speed of $10 m/s$ . The work done by the force of gravity during the time the body reaches its maximum height. (Consider $g = 10 {m/s}^{2}$ )

Discussion

7.	For a wheel rotating at a rate of 60 rpm about an axis passing through its centre, the torque required to stop wheel's rotation in 2 minute will be (Given : MOI of wheel about its axis is 4 kg m2)
Answer» For a wheel rotating at a rate of $60 rpm$ about an axis passing through its centre, the torque required to stop wheel's rotation in 2 minute will be (Given : MOI of wheel about its axis is $4 {kg m}^{2})$

Discussion

8.	Two discs of moment of inertia I1 ,I2 are rotating with angular velocities ω1, ω2 along collinear axes passing through their centre of mass and perpendicular to their plane. If the two are made to rotate combined along the same axis the rotational KE of system will be
Answer» Two discs of moment of inertia $I_{1}$ , $I_{2}$ are rotating with angular velocities $ω_{1}$ , $ω_{2}$ along collinear axes passing through their centre of mass and perpendicular to their plane. If the two are made to rotate combined along the same axis the rotational KE of system will be

Discussion

9.	A small body of mass m=10 kg hangs at one end of a string of length l, the other end of which is fixed. It is given horizontal velocity u at its lowest position. The string just becomes slack, when it covers an angle 120∘ with the initial position. Find the tension in the string at the point of projection. Take g=10 m/s2
Answer» A small body of mass $m = 10 kg$ hangs at one end of a string of length $l$ , the other end of which is fixed. It is given horizontal velocity $u$ at its lowest position. The string just becomes slack, when it covers an angle $120^{\circ}$ with the initial position. Find the tension in the string at the point of projection. Take $g = 10 {m/s}^{2}$

Discussion

10.	2 towers AB and CD are situated a distance d apart. AB is 20m high and CD is 30m high from the ground. An object of mass m is thrown from the top of AB horizontally with a velocity of 10m/s towards CD. Simultaneously another object of mass 2m is thrown from the top of CD at an angle of 60° to the horizontal towards AB with the same magnitude of initial velocity as that of the first abject. The 2 objects move in the same vertical plane, collide in mid air and stick to each other. i) Calculate the distance d between the towers. ii) Find the position where the objects hit the ground. Explain in detail.
Answer» 2 towers AB and CD are situated a distance d apart. AB is 20m high and CD is 30m high from the ground. An object of mass m is thrown from the top of AB horizontally with a velocity of 10m/s towards CD. Simultaneously another object of mass 2m is thrown from the top of CD at an angle of 60° to the horizontal towards AB with the same magnitude of initial velocity as that of the first abject. The 2 objects move in the same vertical plane, collide in mid air and stick to each other. i) Calculate the distance d between the towers. ii) Find the position where the objects hit the ground. Explain in detail.

10.

2 towers AB and CD are situated a distance d apart. AB is 20m high and CD is 30m high from the ground. An object of mass m is thrown from the top of AB horizontally with a velocity of 10m/s towards CD. Simultaneously another object of mass 2m is thrown from the top of CD at an angle of 60° to the horizontal towards AB with the same magnitude of initial velocity as that of the first abject. The 2 objects move in the same vertical plane, collide in mid air and stick to each other. i) Calculate the distance d between the towers. ii) Find the position where the objects hit the ground. Explain in detail.

Answer»

2 towers AB and CD are situated a distance d apart. AB is 20m high and CD is 30m high from the ground. An object of mass m is thrown from the top of AB horizontally with a velocity of 10m/s towards CD. Simultaneously another object of mass 2m is thrown from the top of CD at an angle of 60° to the horizontal towards AB with the same magnitude of initial velocity as that of the first abject. The 2 objects move in the same vertical plane, collide in mid air and stick to each other.

i) Calculate the distance d between the towers.

ii) Find the position where the objects hit the ground.

Explain in detail.

Discussion

11.	A bowling ball is thrown down the alley in such a way that it slides with a speed v0 initially without rolling. What will it it's speed be when (and if) it starts pure rolling? The transition from pure sliding to pure rolling is gradual, so that both sliding and rolling takes place during this interval.
Answer» A bowling ball is thrown down the alley in such a way that it slides with a speed $v_{0}$ initially without rolling. What will it it's speed be when (and if) it starts pure rolling? The transition from pure sliding to pure rolling is gradual, so that both sliding and rolling takes place during this interval.

Discussion

12.	A train running at 30 m/s comes to rest at uniform deceleration within 44 s. The distance travelled by train before coming to rest is
Answer» A train running at $30 m / s$ comes to rest at uniform deceleration within $44 s$ . The distance travelled by train before coming to rest is

Discussion

13.	Two cars 1 and 2 move with velocities v1 and v2 respectively on a straight road in the same direction. When the cars are separated by a distance d, the driver of the car 1 applies brakes and the car moves with uniform retardation a1. Simultaneously, the car 2 starts accelerating with a2. If v1>v2, find the minimum initial separation between the cars to avoid collision between them.
Answer» Two cars 1 and 2 move with velocities $v_{1} a n d v_{2}$ respectively on a straight road in the same direction. When the cars are separated by a distance d, the driver of the car 1 applies brakes and the car moves with uniform retardation $a_{1}$ . Simultaneously, the car 2 starts accelerating with $a_{2}$ . If $v_{1} > v_{2}$ , find the minimum initial separation between the cars to avoid collision between them.

Discussion

14.	എന്താണ് ഭൂഗുരുത്വ ത്വരണം?
Answer» എന്താണ് ഭൂഗുരുത്വ ത്വരണം?

Discussion

15.	A system consists of two identical small balls of mass 2 kg each connected to the two ends of a 1 m long light rod. The system is rotating about a fixed axis through the centre of the rod and perpendicular to it at an angular speed of 9 rad/s. An impulsive force of average magnitude 10 N acts on one of the masses in the direction of its velocity for 0.20 s. Calculate the new angular velocity of the system.
Answer» A system consists of two identical small balls of mass $2 kg$ each connected to the two ends of a $1 m$ long light rod. The system is rotating about a fixed axis through the centre of the rod and perpendicular to it at an angular speed of $9 rad/s$ . An impulsive force of average magnitude $10 N$ acts on one of the masses in the direction of its velocity for $0.20 s$ . Calculate the new angular velocity of the system.

Discussion

16.	A ray of light incident normally on the face AB of the right-angled prism of refractive index of 1.5. The prism is partially immersed in a liquid of unknown refractive index. Find the value of refractive index of liquid so that the ray grazes along the side BC.
Answer» A ray of light incident normally on the face AB of the right-angled prism of refractive index of 1.5. The prism is partially immersed in a liquid of unknown refractive index. Find the value of refractive index of liquid so that the ray grazes along the side BC.

Discussion

17.	The force required to just move a body up the inclined plane is double the force required to just prevent the body from sliding down the plane. If the coefficient of friction is μ, then inclination θ of the plane is
Answer» The force required to just move a body up the inclined plane is double the force required to just prevent the body from sliding down the plane. If the coefficient of friction is $μ$ , then inclination $θ$ of the plane is

Discussion

18.	If a person traveled 15 m at an angle 60∘ North of East. Then, how much he traveled in East direction (in m)
Answer» If a person traveled $15 m$ at an angle $60^{\circ}$ North of East. Then, how much he traveled in East direction $(in m)$

Discussion

19.	A particle moves along a semicircle of radius 5 m in 2 seconds. The magnitude of average velocity of the particle is
Answer» A particle moves along a semicircle of radius $5 m$ in $2$ seconds. The magnitude of average velocity of the particle is

Discussion

20.	A particle stays at rest as seen in a frame. We can conclude that
Answer» A particle stays at rest as seen in a frame. We can conclude that

Discussion

21.	A conducting circular loop of radius r carries a constant current i. It is placed in a uniform magnetic field , such that is perpendicular to the plane of the loop. The magnetic force acting on the loop is? [BIT 1992; MP PET 1994; IIT 1983;MP PMT 1999; AMU (Engg.) 2000]
Answer» A conducting circular loop of radius r carries a constant current i. It is placed in a uniform magnetic field , such that is perpendicular to the plane of the loop. The magnetic force acting on the loop is? [BIT 1992; MP PET 1994; IIT 1983;MP PMT 1999; AMU (Engg.) 2000]

21.

A conducting circular loop of radius r carries a constant current i. It is placed in a uniform magnetic field , such that is perpendicular to the plane of the loop. The magnetic force acting on the loop is? [BIT 1992; MP PET 1994; IIT 1983;MP PMT 1999; AMU (Engg.) 2000]

Answer»

A conducting circular loop of radius r carries a constant current i. It is placed in a uniform magnetic field , such that is perpendicular to the plane of the loop. The magnetic force acting on the loop is?

[BIT 1992; MP PET 1994; IIT 1983;MP PMT 1999; AMU (Engg.) 2000]

Discussion

22.	A body of mass 2 kg is placed on a horizontal surface having kinetic friction 0.4 and static friction 0.5 If force applied on body is 20 Newton find acceleration of body
Answer» A body of mass 2 kg is placed on a horizontal surface having kinetic friction 0.4 and static friction 0.5 If force applied on body is 20 Newton find acceleration of body

Discussion

23.	In the figure, n moles of a monoatomic ideal gas undergo the process ABC as shown in the P−V diagram. The process AB is isothermal and BC is isochoric. The temperature of the gas at A is T0. Total heat given to the gas during the process ABC is measured to be Q. Heat absorbed by the gas in the process BC is
Answer» In the figure, $n$ moles of a monoatomic ideal gas undergo the process $A B C$ as shown in the $P - V$ diagram. The process $A B$ is isothermal and $B C$ is isochoric. The temperature of the gas at $A$ is $T_{0} .$ Total heat given to the gas during the process $A B C$ is measured to be $Q$ . Heat absorbed by the gas in the process $B C$ is

Discussion

24.	For the system shown in figure, find the speed with which the 12 kg block will hit the ground. Take g=10 m/s2.
Answer» For the system shown in figure, find the speed with which the $12 kg$ block will hit the ground. Take $g = 10 {m/s}^{2}$ .

Discussion

25.	Which of the lines in the figure represents the relation between Celsius and Fahrenheit temperatures?
Answer» Which of the lines in the figure represents the relation between Celsius and Fahrenheit temperatures?

Discussion

26.	The capacitance of a parallel plate condenser is C. The plates are square plates of side 1 unit. The plates are replaced by circular plates of diameter 1 unit. The capacitance now becomes?(with all others parameters remaining the same)
Answer» The capacitance of a parallel plate condenser is C. The plates are square plates of side 1 unit. The plates are replaced by circular plates of diameter 1 unit. The capacitance now becomes?(with all others parameters remaining the same)

Discussion

27.	20 gm ice at −10 ∘C is mixed with m gm steam at 100 ∘C. The minimum value of m so that finally all ice and steam converts into water is [ Use, specific heat and latent heat as Cice=0.5 cal/gm ∘C,Cwater=1 cal/gm ∘C,Lmelt =80 cal/gm and Lvapor =540 cal/gm ]
Answer» $20 gm$ ice at $- 10^{\circ} C$ is mixed with $m gm$ steam at $100^{\circ} C$ . The minimum value of $m$ so that finally all ice and steam converts into water is $[$ Use, specific heat and latent heat as $C_{i c e} = 0.5 cal/gm^{\circ} C, C_{water} = 1 cal/gm^{\circ} C, L_{m e l t}$ $= 80 cal/gm$ and $L_{v a p o r}$ $= 540 cal/gm$ $]$

Discussion

28.	A conducting square loop having edges of length 2.0 cm is rotated through 180∘ about a diagonal in 0.20 a. A magnetic field B exists in the region which is perpendicular to the loop in its initial position. If the average induced emf during the rotation is 20 mV, find the magnitude of the magnetic field.
Answer» A conducting square loop having edges of length 2.0 cm is rotated through $180^{\circ}$ about a diagonal in 0.20 a. A magnetic field B exists in the region which is perpendicular to the loop in its initial position. If the average induced emf during the rotation is 20 mV, find the magnitude of the magnetic field.

Discussion

29.	The ratio of the energies of the hydrogen atom in its first to second excited state is
Answer» The ratio of the energies of the hydrogen atom in its first to second excited state is

Discussion

30.	A particle is projected with a velocity v such that its range on the horizontal plane is twice the greatest height attained by it. The range of the projectile is (where g is acceleration due to gravity)
Answer» A particle is projected with a velocity v such that its range on the horizontal plane is twice the greatest height attained by it. The range of the projectile is (where g is acceleration due to gravity)

Discussion

31.	In the circuit shown is figure, switch is closed then find the work done by battery till next steady state is achieved.
Answer» In the circuit shown is figure, switch is closed then find the work done by battery till next steady state is achieved.

Discussion

32.	The cylindrical tube of a spray pump has radius R. One end of the tube has n fine holes each of radius r. If the speed of the liquid in the tube is V, then the speed of the ejection of the liquid through the holes is
Answer» The cylindrical tube of a spray pump has radius $R$ . One end of the tube has $n$ fine holes each of radius $r$ . If the speed of the liquid in the tube is $V$ , then the speed of the ejection of the liquid through the holes is

Discussion

33.	When a capacitor of capacitance C is filled with a dielectric (i.e. thickness of the dielectric is equal to the spacing between the plates) of dielectric constant k, what is the new capacitance?
Answer» When a capacitor of capacitance C is filled with a dielectric (i.e. thickness of the dielectric is equal to the spacing between the plates) of dielectric constant k, what is the new capacitance?

Discussion

34.	What is the angle between the following vectors? →A=3^i−2^j+^k →B=2^i+6^j−6^k
Answer» What is the angle between the following vectors? $\to A = 3^i - 2^j +^k$ $\to B = 2^i + 6^j - 6^k$

34.

What is the angle between the following vectors? →A=3^i−2^j+^k →B=2^i+6^j−6^k

Answer»

What is the angle between the following vectors?

$\to A = 3^i - 2^j +^k$

$\to B = 2^i + 6^j - 6^k$

Discussion

35.	The electric field in a region is radially outward with magnitude E=Aγ0. The charge contained in a sphere of radius γ0 centred at the origin is
Answer» The electric field in a region is radially outward with magnitude $E = A γ_{0}$ . The charge contained in a sphere of radius $γ_{0}$ centred at the origin is

Discussion

36.	Potential at the centroid of an equilateral triangle of side ‘a’, when equal charges each of magnitude ‘Q’ are placed at the vertices of the triangle is?
Answer» Potential at the centroid of an equilateral triangle of side ‘a’, when equal charges each of magnitude ‘Q’ are placed at the vertices of the triangle is?

Discussion

37.	If the direction cosines of a line are l, m and n then which of the following is true?
Answer» If the direction cosines of a line are l, m and n then which of the following is true?

Discussion

38.	Light of wavelength 2475 A∘ is incident on Barium. Photoelectrons emitted describe a circle of radius 100 cm in a magnetic field of flux density 1√17×10−5 T. Work function of the barium (in eV) is (Given em=1.7×1011 CKg−1)
Answer» Light of wavelength $2475 A^{\circ}$ is incident on Barium. Photoelectrons emitted describe a circle of radius $100 c m$ in a magnetic field of flux density $\frac{1}{\sqrt{17}} \times 10^{- 5} T$ . Work function of the barium (in $e V$ ) is (Given $\frac{e}{m} = 1.7 \times 10^{11} C K g^{- 1})$

38.

Light of wavelength 2475 A∘ is incident on Barium. Photoelectrons emitted describe a circle of radius 100 cm in a magnetic field of flux density 1√17×10−5 T. Work function of the barium (in eV) is (Given em=1.7×1011 CKg−1)

Answer»

Light of wavelength $2475 A^{\circ}$ is incident on Barium. Photoelectrons emitted describe a circle of radius $100 c m$ in a magnetic field of flux density $\frac{1}{\sqrt{17}} \times 10^{- 5} T$ . Work function of the barium (in $e V$ ) is (Given $\frac{e}{m} = 1.7 \times 10^{11} C K g^{- 1})$

Discussion

39.	List - 1 gives different lens configurations. Radius of curvature of each surface is depicted in figure. Refractive index of glass of lens is 32 and medium in which it is placed is 1.2 . Rays of light parallel to axis of lens from left passes through lens and get focused at distance 'x' from lens. List - 2 gives value of 'x' then correct match is.
Answer» List - 1 gives different lens configurations. Radius of curvature of each surface is depicted in figure. Refractive index of glass of lens is $\frac{3}{2}$ and medium in which it is placed is 1.2 . Rays of light parallel to axis of lens from left passes through lens and get focused at distance 'x' from lens. List - 2 gives value of 'x' then correct match is.

Discussion

40.	An L-shaped glass tube is kept inside a bus that is moving with constant acceleration. During the motion, level of the liquid in the left arm is at 12 cm whereas in the right arm, it is at 8 cm when the orientation of the tube is as shown. Assuming that the diameter of the tube is much smaller than the levels of the liquid and neglecting effects of surface tension, the acceleration of the bus will be (g=10 m/s2)
Answer» An L-shaped glass tube is kept inside a bus that is moving with constant acceleration. During the motion, level of the liquid in the left arm is at $12 cm$ whereas in the right arm, it is at $8 cm$ when the orientation of the tube is as shown. Assuming that the diameter of the tube is much smaller than the levels of the liquid and neglecting effects of surface tension, the acceleration of the bus will be $({g=10 m/s}^{2})$

Discussion

41.	When you speak to you friend, which of the following parameters have a unique value in the sound produced?
Answer» When you speak to you friend, which of the following parameters have a unique value in the sound produced?

Discussion

42.	A small solid sphere of mass m and radius r rolls without slipping on the inside a large hemisphere of radius R . The axis of symmetry of the hemisphere is vertical. Sphere starts at the top from rest. The sphere will exert a normal force on the hemisphere at its bottom equal to (n)1714mg. Then the value of n is
Answer» A small solid sphere of mass $m$ and radius $r$ rolls without slipping on the inside a large hemisphere of radius $R$ . The axis of symmetry of the hemisphere is vertical. Sphere starts at the top from rest. The sphere will exert a normal force on the hemisphere at its bottom equal to $(n) \frac{17}{14} m g$ . Then the value of $n$ is

Discussion

43.	If the radius of the earth were to shrink by one per cent, its mass remaining the same, the acceleration due to gravity on the earth's surface would :
Answer» If the radius of the earth were to shrink by one per cent, its mass remaining the same, the acceleration due to gravity on the earth's surface would :

Discussion

44.	A 60 Hz exciter sets string into a mode as shown in figure. Length of string is 45 cm. If displacement amplitudes of particles at x=7.5, x=18 & x=27 are A1,A2 & A3, then
Answer» A 60 $H z$ exciter sets string into a mode as shown in figure. Length of string is 45 $c m$ . If displacement amplitudes of particles at $x = 7.5$ , $x = 18$ & $x = 27$ are $A_{1}, A_{2} & A_{3}$ , then

Discussion

45.	Figure shows a conducting rod of negligible resistance that can slide on a smooth U-shaped rail made of wire of resistance 1 Ωm−1 . Position of the conducting rod at t=0 is shown. A time-dependent magnetic field B=2t (tesla) is switched on at t=0.The magnitude of the force required to move the conducting rod at a constant speed of 5 cm/s at the some intstant of t=2 s is equal to 1000x×10−3 N, where x is (Answer upto 2 decimal places).
Answer» Figure shows a conducting rod of negligible resistance that can slide on a smooth U-shaped rail made of wire of resistance 1 $Ω m^{- 1}$ . Position of the conducting rod at $t = 0$ is shown. A time-dependent magnetic field $B = 2 t$ (tesla) is switched on at $t = 0$ .The magnitude of the force required to move the conducting rod at a constant speed of $5 c m / s$ at the some intstant of $t = 2 s$ is equal to 1000 $x \times 10^{- 3} N$ , where $x$ is (Answer upto 2 decimal places).

Discussion

46.	1.which type of material(wire) is used in resistance thermometer? 2.which thermometer is more sensitive? mercury or gas 3.which range of temp. can you measure using platinum resistance thermometer?
Answer» 1.which type of material(wire) is used in resistance thermometer? 2.which thermometer is more sensitive? mercury or gas 3.which range of temp. can you measure using platinum resistance thermometer?

Discussion

47.	If the speed of the particle is v=4t3−3t2+3 m/s, the distance of the particle as a function of time t and the average speed in 2 sec respectively are
Answer» If the speed of the particle is $v = 4 t^{3} - 3 t^{2} + 3 m/s$ , the distance of the particle as a function of time $t$ and the average speed in $2 sec$ respectively are

Discussion

48.	Effective resistance of three conductors in parallel is 6047 ohm . One of the wire breaks and the effective resistance is 158 ohm . The resistance of the wire that broken is
Answer» Effective resistance of three conductors in parallel is $\frac{60}{47} o h m$ . One of the wire breaks and the effective resistance is $\frac{15}{8} o h m$ . The resistance of the wire that broken is

Discussion

49.	A thin rod of mass M and length L is rotating about an axis perpendicular to length of rod and passing through its centre. If half of the total rod that lies at one side of axis is cut and removed then the moment of inertia of remaining rod is
Answer» A thin rod of mass M and length L is rotating about an axis perpendicular to length of rod and passing through its centre. If half of the total rod that lies at one side of axis is cut and removed then the moment of inertia of remaining rod is

Discussion

50.	Two bodies of masses m1 and m2 are initially at rest placed infinite distance apart. They are then allowed to move towards each other under mutual gravitational attraction. Their relative velocity when they are r distance apart is
Answer» Two bodies of masses $m_{1}$ and $m_{2}$ are initially at rest placed infinite distance apart. They are then allowed to move towards each other under mutual gravitational attraction. Their relative velocity when they are r distance apart is

Discussion

Explore topic-wise InterviewSolutions in Current Affairs.

A thin ring of radius R is made of a material of density ρ and Young’s modulus Y. If the ring is rotated about its centre in its own plane with angular velocity ω and the small increase in its radius is ρω2R3λY, then find λ___

A parallel plate capacitor has capacitance C. When its area filled with a dielectric of dielectric constant k = 2, as shown in figure

Speed of sound in air is 332 m/s at NTP. What will be the speed of sound in hydrogen at NTP if the density of hydrogen at NTP is (1/16) that of air?

A body of mass 2 kg is thrown vertically upwards with an initial speed of 10 m/s. The work done by the force of gravity during the time the body reaches its maximum height. (Consider g=10 m/s2)

For a wheel rotating at a rate of 60 rpm about an axis passing through its centre, the torque required to stop wheel's rotation in 2 minute will be (Given : MOI of wheel about its axis is 4 kg m2)

Two discs of moment of inertia I1 ,I2 are rotating with angular velocities ω1, ω2 along collinear axes passing through their centre of mass and perpendicular to their plane. If the two are made to rotate combined along the same axis the rotational KE of system will be

A train running at 30 m/s comes to rest at uniform deceleration within 44 s. The distance travelled by train before coming to rest is

എന്താണ് ഭൂഗുരുത്വ ത്വരണം?

A ray of light incident normally on the face AB of the right-angled prism of refractive index of 1.5. The prism is partially immersed in a liquid of unknown refractive index. Find the value of refractive index of liquid so that the ray grazes along the side BC.

The force required to just move a body up the inclined plane is double the force required to just prevent the body from sliding down the plane. If the coefficient of friction is μ, then inclination θ of the plane is

If a person traveled 15 m at an angle 60∘ North of East. Then, how much he traveled in East direction (in m)

A particle moves along a semicircle of radius 5 m in 2 seconds. The magnitude of average velocity of the particle is

A particle stays at rest as seen in a frame. We can conclude that

A conducting circular loop of radius r carries a constant current i. It is placed in a uniform magnetic field , such that is perpendicular to the plane of the loop. The magnetic force acting on the loop is? [BIT 1992; MP PET 1994; IIT 1983;MP PMT 1999; AMU (Engg.) 2000]

A body of mass 2 kg is placed on a horizontal surface having kinetic friction 0.4 and static friction 0.5 If force applied on body is 20 Newton find acceleration of body

For the system shown in figure, find the speed with which the 12 kg block will hit the ground. Take g=10 m/s2.

Which of the lines in the figure represents the relation between Celsius and Fahrenheit temperatures?

The capacitance of a parallel plate condenser is C. The plates are square plates of side 1 unit. The plates are replaced by circular plates of diameter 1 unit. The capacitance now becomes?(with all others parameters remaining the same)

20 gm ice at −10 ∘C is mixed with m gm steam at 100 ∘C. The minimum value of m so that finally all ice and steam converts into water is [ Use, specific heat and latent heat as Cice=0.5 cal/gm ∘C,Cwater=1 cal/gm ∘C,Lmelt =80 cal/gm and Lvapor =540 cal/gm ]

The ratio of the energies of the hydrogen atom in its first to second excited state is

A particle is projected with a velocity v such that its range on the horizontal plane is twice the greatest height attained by it. The range of the projectile is (where g is acceleration due to gravity)

In the circuit shown is figure, switch is closed then find the work done by battery till next steady state is achieved.

The cylindrical tube of a spray pump has radius R. One end of the tube has n fine holes each of radius r. If the speed of the liquid in the tube is V, then the speed of the ejection of the liquid through the holes is

When a capacitor of capacitance C is filled with a dielectric (i.e. thickness of the dielectric is equal to the spacing between the plates) of dielectric constant k, what is the new capacitance?

What is the angle between the following vectors? →A=3^i−2^j+^k →B=2^i+6^j−6^k

The electric field in a region is radially outward with magnitude E=Aγ0. The charge contained in a sphere of radius γ0 centred at the origin is

Potential at the centroid of an equilateral triangle of side ‘a’, when equal charges each of magnitude ‘Q’ are placed at the vertices of the triangle is?

If the direction cosines of a line are l, m and n then which of the following is true?

Light of wavelength 2475 A∘ is incident on Barium. Photoelectrons emitted describe a circle of radius 100 cm in a magnetic field of flux density 1√17×10−5 T. Work function of the barium (in eV) is (Given em=1.7×1011 CKg−1)

When you speak to you friend, which of the following parameters have a unique value in the sound produced?

If the radius of the earth were to shrink by one per cent, its mass remaining the same, the acceleration due to gravity on the earth's surface would :

A 60 Hz exciter sets string into a mode as shown in figure. Length of string is 45 cm. If displacement amplitudes of particles at x=7.5, x=18 & x=27 are A1,A2 &amp; A3, then

1.which type of material(wire) is used in resistance thermometer? 2.which thermometer is more sensitive? mercury or gas 3.which range of temp. can you measure using platinum resistance thermometer?

If the speed of the particle is v=4t3−3t2+3 m/s, the distance of the particle as a function of time t and the average speed in 2 sec respectively are

Effective resistance of three conductors in parallel is 6047 ohm . One of the wire breaks and the effective resistance is 158 ohm . The resistance of the wire that broken is

A thin rod of mass M and length L is rotating about an axis perpendicular to length of rod and passing through its centre. If half of the total rod that lies at one side of axis is cut and removed then the moment of inertia of remaining rod is

Two bodies of masses m1 and m2 are initially at rest placed infinite distance apart. They are then allowed to move towards each other under mutual gravitational attraction. Their relative velocity when they are r distance apart is

A 60 Hz exciter sets string into a mode as shown in figure. Length of string is 45 cm. If displacement amplitudes of particles at x=7.5, x=18 & x=27 are A1,A2 & A3, then