50278 + Interview Questions in Physics

1.	Find the resistance of the circuit shown below figure between points A and D.
Answer» Find the resistance of the circuit shown below figure between points A and D.

Discussion

2.	A projectile is fired with velocity u making angle θ with the horizontal. What is the change in velocity when it is at the highest point
Answer» A projectile is fired with velocity $u$ making angle $θ$ with the horizontal. What is the change in velocity when it is at the highest point

Discussion

3.	The friction coefficient between the table and the block shown in figure (6-E4) is 0.2. Find the tensions in the two strings.
Answer» The friction coefficient between the table and the block shown in figure (6-E4) is 0.2. Find the tensions in the two strings.

Discussion

4.	The same retarding force is applied to stop a train. The train stops after 80 m. If the speed is doubled, then the distance will be
Answer» The same retarding force is applied to stop a train. The train stops after 80 m. If the speed is doubled, then the distance will be

4.

The same retarding force is applied to stop a train. The train stops after 80 m. If the speed is doubled, then the distance will be

Answer»

The same retarding force is applied to stop a train. The train stops after 80 m. If the speed is doubled, then the distance will be

Discussion

5.	What is the resultant of three coplanar forces 300 N at 0o, 400 N at 30∘ and 400 N at 150∘ with x− axis?
Answer» What is the resultant of three coplanar forces $300 N$ at $0^{o}$ , $400 N$ at $30^{\circ}$ and $400 N$ at $150^{\circ}$ with $x -$ axis?

Discussion

6.	A particle starts from rest with a time-varying acceleration, a=(2t−4). Here t is in s and a in m/s2. After what time (in s) particle comes to rest?
Answer» A particle starts from rest with a time-varying acceleration, $a = (2 t - 4)$ . Here $t$ is in $s$ and $a$ in $m / s^{2}$ . After what time (in $s$ ) particle comes to rest?

Discussion

7.	When a tuning fork of frequency 341 is sounded with another tuning fork, six beats per second are heard. When the second tuning fork is loaded with wax and sounded with the first tuning fork, the number of beats is two per second. The natural frequency of the second tuning fork is [MP PET 1989]
Answer» When a tuning fork of frequency 341 is sounded with another tuning fork, six beats per second are heard. When the second tuning fork is loaded with wax and sounded with the first tuning fork, the number of beats is two per second. The natural frequency of the second tuning fork is [MP PET 1989]

7.

When a tuning fork of frequency 341 is sounded with another tuning fork, six beats per second are heard. When the second tuning fork is loaded with wax and sounded with the first tuning fork, the number of beats is two per second. The natural frequency of the second tuning fork is [MP PET 1989]

Answer»

When a tuning fork of frequency 341 is sounded with another tuning fork, six

beats per second are heard. When the second tuning fork is loaded with wax

and sounded with the first tuning fork, the number of beats is two per

second. The natural frequency of the second tuning fork is

[MP PET 1989]

Discussion

8.	A metallic rod of length ′l′ is tied to a string of length 2l and made to rotate with angular speed ω on a horizontal table with one end of the string fixed. If there is a vertical magnetic field ‘B′ in the region, the e.m.f. induced across the ends of the rod is
Answer» A metallic rod of length $^{'} l^{'}$ is tied to a string of length $2 l$ and made to rotate with angular speed $ω$ on a horizontal table with one end of the string fixed. If there is a vertical magnetic field $‘ B^{'}$ in the region, the e.m.f. induced across the ends of the rod is

Discussion

9.	A particle experiences a constant acceleration for 20 sec after starting from rest. If it travels a distance S1 in the first 10 sec and a distance S2 in the next 10 sec, then
Answer» A particle experiences a constant acceleration for 20 sec after starting from rest. If it travels a distance $S_{1}$ in the first 10 sec and a distance $S_{2}$ in the next 10 sec, then

9.

A particle experiences a constant acceleration for 20 sec after starting from rest. If it travels a distance S1 in the first 10 sec and a distance S2 in the next 10 sec, then

Answer»

A particle experiences a constant acceleration for 20 sec after starting from rest. If it travels a distance $S_{1}$ in the first 10 sec and a distance $S_{2}$ in the next 10 sec, then

Discussion

10.	A longitudinal sound wave given by p=5sinπ3(x−400t) (p is in N/m2, x is in metres and t is in seconds) is sent down a closed organ pipe. If the pipe vibrates in its second overtone, the length of the pipe is
Answer» A longitudinal sound wave given by $p = 5 sin \frac{π}{3} (x - 400 t)$ ( $p$ is in ${N/m}^{2}$ , $x$ is in metres and $t$ is in seconds) is sent down a closed organ pipe. If the pipe vibrates in its second overtone, the length of the pipe is

Discussion

11.	(a) Define wavefront. Use Huygens' principle to verify the laws of refraction. (b) How is linearly polarised light obtained by the process of scattering of light ? Find the Brewster angle for air-glass interface, when the refractive index of glass =1.5.
Answer» (a) Define wavefront. Use Huygens' principle to verify the laws of refraction. (b) How is linearly polarised light obtained by the process of scattering of light ? Find the Brewster angle for air-glass interface, when the refractive index of glass =1.5.

Discussion

12.	A convex lens of diameter 8.0 cm is used to focus a parallel bam of light of wavelength 620 nm. If the light be focused at a distance of 20 cm from the lens, what would be th eradius of the central bright spot formed?
Answer» A convex lens of diameter 8.0 cm is used to focus a parallel bam of light of wavelength 620 nm. If the light be focused at a distance of 20 cm from the lens, what would be th eradius of the central bright spot formed?

Discussion

13.	A rectangular wire-loop of width a is suspended from the insulated pan of a spring balance as shown in figure (34 - E5). A current i exists in the anticlock wise direction in the loop. A magnetic field B exists in the lower region. Find the change in the tension of the spring if the current in the loop is reversed.
Answer» A rectangular wire-loop of width a is suspended from the insulated pan of a spring balance as shown in figure (34 - E5). A current i exists in the anticlock wise direction in the loop. A magnetic field B exists in the lower region. Find the change in the tension of the spring if the current in the loop is reversed.

13.

A rectangular wire-loop of width a is suspended from the insulated pan of a spring balance as shown in figure (34 - E5). A current i exists in the anticlock wise direction in the loop. A magnetic field B exists in the lower region. Find the change in the tension of the spring if the current in the loop is reversed.

Answer»

A rectangular wire-loop of width a is suspended from the insulated pan of a spring balance as shown in figure (34 - E5). A current i exists in the anticlock wise direction in the loop. A magnetic field B exists in the lower region. Find the change in the tension of the spring if the current in the loop is reversed.

Discussion

14.	A balloon which always remains spherical on inflation, is being inflated pumping in 900 cubic cm of gas per second. Find the rate at which the radius of the balloon increases when the radius is 15 cm.
Answer» A balloon which always remains spherical on inflation, is being inflated pumping in 900 cubic cm of gas per second. Find the rate at which the radius of the balloon increases when the radius is 15 cm.

Discussion

15.	A block of mass m, attached to a spring of spring constant k, oscillates on a smooth horizontal table. The other end of the spring is fixed to a wall. If it has a speed v when the spring is at its natural length, how far will it move on the table before coming to an instantaneous rest?
Answer» A block of mass m, attached to a spring of spring constant k, oscillates on a smooth horizontal table. The other end of the spring is fixed to a wall. If it has a speed v when the spring is at its natural length, how far will it move on the table before coming to an instantaneous rest?

Discussion

16.	Eight small drops of equal size are falling through air with a steady velocity of 10 cm/sec. If the drops coalesce, what would be the terminal velocity of the bigger drop?
Answer» Eight small drops of equal size are falling through air with a steady velocity of $10 cm/sec$ . If the drops coalesce, what would be the terminal velocity of the bigger drop?

Discussion

17.	A pilot of mass 75 kg in a jet aircraft executes a loop with a constant speed of 360 km/hr. If the radius of the loop is 200 m, the force exerted by seat on the pilot at the top of the loop is (Take g=10 m/s2)
Answer» A pilot of mass $75 kg$ in a jet aircraft executes a loop with a constant speed of $360 km/hr$ . If the radius of the loop is $200 m$ , the force exerted by seat on the pilot at the top of the loop is $(Take g = 10 {m/s}^{2})$

Discussion

18.	∫(t√t+√tt2)dt is equal to
Answer» $\int (\frac{t \sqrt{t} + \sqrt{t}}{t^{2}}) d t$ is equal to

Discussion

19.	A particle was initially at point at height Re from the earth’s surface The work done to bring this particle to earth’s surface is −XGMem2Re. Find the value of X (m= mass of particle).___
Answer» A particle was initially at point at height $R_{e}$ from the earth’s surface The work done to bring this particle to earth’s surface is $\frac{- X G M_{e} m}{2 R_{e}}$ . Find the value of X (m= mass of particle).___

Discussion

20.	A cylinder of radius R made of a material of thermal conductivity K1 is surrounded by a cylindrical shell of inner radius R and outer radius 2R made of material of thermal conductivity K2. The two ends of the combined system are maintained at two different temperatures. There is no loss of heat across the cylindrical surface and the system is in steady state. The effective thermal conductivity of the system is
Answer» A cylinder of radius R made of a material of thermal conductivity $K_{1}$ is surrounded by a cylindrical shell of inner radius R and outer radius 2R made of material of thermal conductivity $K_{2}$ . The two ends of the combined system are maintained at two different temperatures. There is no loss of heat across the cylindrical surface and the system is in steady state. The effective thermal conductivity of the system is

Discussion

21.	The activity of a radioactive sample is A1 at time t1 and A2 at time t2. If Tav is the average life time of the radioactive sample, then the number of atoms that decay during interval (t2−t1)
Answer» The activity of a radioactive sample is $A_{1}$ at time $t_{1}$ and $A_{2}$ at time $t_{2}$ . If $T_{a v}$ is the average life time of the radioactive sample, then the number of atoms that decay during interval $(t_{2} - t_{1})$

Discussion

22.	In a radioactive element the fraction of initial amount remaining after its mean life time is :
Answer» In a radioactive element the fraction of initial amount remaining after its mean life time is :

Discussion

23.	The position x of a particle varies with time (t) as x=at2−bt3. The acceleration of the particle will be equal to zero at time
Answer» The position x of a particle varies with time (t) as $x = a t^{2} - b t^{3}$ . The acceleration of the particle will be equal to zero at time

Discussion

24.	The linear charge density on a dielectric ring of radius R varies with θ as λ=λ0cosθ2, where λ0 is a constant. Find the potential at the centre of the ring. [in volt]
Answer» The linear charge density on a dielectric ring of radius R varies with $θ$ as $λ = λ_{0} cos \frac{θ}{2},$ where $λ_{0}$ is a constant. Find the potential at the centre of the ring. [in volt]

Discussion

25.	In the shown figure mA,mB and mC are the masses of the three blocks, the incline is frictionless mA=5 kg,mB=10 kg,mC= 2kg. coefficient of friction between A and B is 0.5 and between B and C is 0.1 (Take g = 10 m/s2) On the basis of above data answer the following questions. What is the frictional force on block A
Answer» In the shown figure $m_{A}, m_{B} a n d m_{C}$ are the masses of the three blocks, the incline is frictionless $m_{A} = 5 k g, m_{B} = 10 k g, m_{C} = 2 k g$ . coefficient of friction between A and B is 0.5 and between B and C is 0.1 (Take g = 10 $m / s^{2}$ ) On the basis of above data answer the following questions. What is the frictional force on block A

25.

In the shown figure mA,mB and mC are the masses of the three blocks, the incline is frictionless mA=5 kg,mB=10 kg,mC= 2kg. coefficient of friction between A and B is 0.5 and between B and C is 0.1 (Take g = 10 m/s2) On the basis of above data answer the following questions. What is the frictional force on block A

Answer»

In the shown figure $m_{A}, m_{B} a n d m_{C}$ are the masses of the three blocks, the incline is frictionless $m_{A} = 5 k g, m_{B} = 10 k g, m_{C} = 2 k g$ . coefficient of friction between A and B is 0.5 and between B and C is 0.1 (Take g = 10 $m / s^{2}$ ) On the basis of above data answer the following questions.

What is the frictional force on block A

Discussion

26.	A body of mass 5 kg is moving along a straight line with a velocity of 2 ms−1. A variable force F started acting on it for a time period of 0.5 s as shown in force - time curve. The final velocity of the block is
Answer» A body of mass $5 kg$ is moving along a straight line with a velocity of $2 {ms}^{- 1}$ . A variable force $F$ started acting on it for a time period of $0.5 s$ as shown in force - time curve. The final velocity of the block is

Discussion

27.	Light of frequency 8×1015Hz is incident on a substance of photoelectric work function 6.125 eV. The maximum kinetic energy of the emitted photoelectrons is
Answer» Light of frequency $8 \times 10^{15} H z$ is incident on a substance of photoelectric work function 6.125 eV. The maximum kinetic energy of the emitted photoelectrons is

Discussion

28.	A charge ‘q’ is moving towards the centre of an earthed conducting sphere of radius ‘b’ with uniform velocity ‘v’. Distance of two points A and B from the centre of sphere are ‘3a’ and ‘2a’. Conducting sphere is earthed with an ammeter and resistance in series as shown Heat energy produced in the resistance till the point charge moves from A to B is
Answer» A charge ‘q’ is moving towards the centre of an earthed conducting sphere of radius ‘b’ with uniform velocity ‘v’. Distance of two points A and B from the centre of sphere are ‘3a’ and ‘2a’. Conducting sphere is earthed with an ammeter and resistance in series as shown Heat energy produced in the resistance till the point charge moves from A to B is

Discussion

29.	The given figure shows the isotherms of a fixed mass of an ideal gas at three temperatures TA,TB and TC then
Answer» The given figure shows the isotherms of a fixed mass of an ideal gas at three temperatures $T_{A}, T_{B}$ and $T_{C}$ then

Discussion

30.	A certain quantity of heat is given to a wire of length‘L’ and its temperature raises by T. γ is the co – efficient of volume expansion of wire and ‘Y’ is young’s modulus of wire, the energy stored per unit volume in the wire is
Answer» A certain quantity of heat is given to a wire of length‘L’ and its temperature raises by T. γ is the co – efficient of volume expansion of wire and ‘Y’ is young’s modulus of wire, the energy stored per unit volume in the wire is

Discussion

31.	The maximum charge that can be given to a conducting sphere [in mC] of radius 1m if the dielectric strength of air is 3×106 V/m. is
Answer» The maximum charge that can be given to a conducting sphere [in mC] of radius 1m if the dielectric strength of air is $3 \times 10^{6}$ V/m. is

Discussion

32.	Given that the displacement of an oscillating particle is given by y=A sin[Bx + Ct + D]. The dimension formula for ABCD is (where x is displacement and t is time)
Answer» Given that the displacement of an oscillating particle is given by $y = A sin[Bx + Ct + D]$ . The dimension formula for ABCD is (where x is displacement and t is time)

Discussion

33.	In air , a metallic sphere with an internal cavity weighs 40g and in water weighs 20g . the volume of the cavity if the density of material with cavity is 8g/cm^3
Answer» In air , a metallic sphere with an internal cavity weighs 40g and in water weighs 20g . the volume of the cavity if the density of material with cavity is 8g/cm^3

Discussion

34.	A block of mass 100 g slides on a rough horizontal surface. If the speed of the block decreases from 10 m s−1 to 5 m s−1, find the thermal energy developed in the process.
Answer» A block of mass 100 g slides on a rough horizontal surface. If the speed of the block decreases from 10 m $s^{- 1}$ to 5 m $s^{- 1}$ , find the thermal energy developed in the process.

Discussion

35.	Figure shows a hemisphere and a supported rod. Hemisphere is moving right with a uniform velocity v2 and the end of rod which is in contact with ground is moving left with a velocity v1. The rate at which the angle θ is decreasing will be
Answer» Figure shows a hemisphere and a supported rod. Hemisphere is moving right with a uniform velocity $v_{2}$ and the end of rod which is in contact with ground is moving left with a velocity $v_{1}$ . The rate at which the angle $θ$ is decreasing will be

Discussion

36.	Find out acceleration of the block. Initially the block is at rest. μs = 0.5 μK = 0.3
Answer» Find out acceleration of the block. Initially the block is at rest. $μ_{s}$ = 0.5 $μ_{K}$ = 0.3

36.

Find out acceleration of the block. Initially the block is at rest. μs = 0.5 μK = 0.3

Answer»

Find out acceleration of the block. Initially the block is at rest.

$μ_{s}$ = 0.5

$μ_{K}$ = 0.3

Discussion

37.	A coin is pushed down tangentially from an angular position θ on a cylindrical surface, with a velocity v as shown in the figure. If the coefficient of friction between the coin and surface is μ, find the tangential acceleration of the coin.
Answer» A coin is pushed down tangentially from an angular position $θ$ on a cylindrical surface, with a velocity v as shown in the figure. If the coefficient of friction between the coin and surface is $μ$ , find the tangential acceleration of the coin.

37.

A coin is pushed down tangentially from an angular position θ on a cylindrical surface, with a velocity v as shown in the figure. If the coefficient of friction between the coin and surface is μ, find the tangential acceleration of the coin.

Answer»

A coin is pushed down tangentially from an angular position $θ$ on a cylindrical surface, with a velocity v as shown in the figure. If the coefficient of friction between the coin and surface is $μ$ , find the tangential acceleration of the coin.

Discussion

38.	For the spring block arrangement as shown in figure: Given that k1=2k2. If force applied by the first spring on the block is F1 and force applied by the second spring on the block is F2, choose the correct option if the block is in equilibrium with the action of an external force 30 N on the block.
Answer» For the spring block arrangement as shown in figure: Given that $k_{1} = 2 k_{2}$ . If force applied by the first spring on the block is $F_{1}$ and force applied by the second spring on the block is $F_{2}$ , choose the correct option if the block is in equilibrium with the action of an external force $30 N$ on the block.

Discussion

39.	An ideal solenoid of cross-sectional area 10−4 m2 has 500 turns per metre. At the centre of this solenoid, another coil of 100 turns is wrapped closely around it. If the current in the coil changes from 0 to 2 A in 3.14 millisecond, the emf developed in the second coil is
Answer» An ideal solenoid of cross-sectional area $10^{- 4} m^{2}$ has 500 turns per metre. At the centre of this solenoid, another coil of 100 turns is wrapped closely around it. If the current in the coil changes from 0 to 2 A in 3.14 millisecond, the emf developed in the second coil is

Discussion

40.	Which of the following option is incorrect? List IList II(A) The minimum value of the expressionsec4αtan2β+sec4βtan2α ∀ α,β∈(0,π/2) is(1) 1(B) If z1, z2 are two non-zero complex numberssatisfying the equation∣∣∣z1+z2z1−z2∣∣∣=1 , then the value of z1z2+¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯(z1z2) is(2) 2(C) Number of integers in the range of functiony=x2+x+3x2+2x+6, x∈R is(3) 0(D) If y=(3)(−3)1/(1−x),thenlimx→1+y is(4) 8
Answer» Which of the following option is incorrect? $\begin{matrix} List I & List II \begin{matrix} (A) The minimum value of the expression \frac{{sec}^{4} α}{{tan}^{2} β} + \frac{{sec}^{4} β}{{tan}^{2} α} \forall α, β \in (0, π / 2) is \end{matrix} & (1) 1 \begin{matrix} (B) If z_{1}, z_{2} are two non-zero complex numbers satisfying the equation ∣ ∣ ∣ \frac{z_{1} + z_{2}}{z_{1} - z_{2}} ∣ ∣ ∣ = 1, then the value of \frac{z_{1}}{z_{2}} + ¯ ¯¯¯¯¯¯¯¯¯¯¯¯¯ ¯ (\frac{z_{1}}{z_{2}}) is \end{matrix} & (2) 2 \begin{matrix} (C) Number of integers in the range of function y = \frac{x^{2} + x + 3}{x^{2} + 2 x + 6}, x \in R is \end{matrix} & (3) 0 \begin{matrix} (D) If y = (3)^{(- 3)^{1 / (1 - x)}}, then lim x \to 1^{+} y is \end{matrix} & (4) 8 \end{matrix}$

Discussion

41.	A point P moves in counter-clockwise direction on a circular path as shown in the figure. The movement of 'P' is such that it sweeps out a length s=t3+5, where s is in meters and t is in seconds. The radius of the path is 20 m. The acceleration of 'P' when t = 2 s is nearly
Answer» A point P moves in counter-clockwise direction on a circular path as shown in the figure. The movement of 'P' is such that it sweeps out a length $s = t^{3} + 5$ , where s is in meters and t is in seconds. The radius of the path is 20 m. The acceleration of 'P' when t = 2 s is nearly

Discussion

42.	The figure shows a spherical shell of mass M. The point A is not at the centre but away from the centre of the shell. If a particle of mass m is placed at A, then
Answer» The figure shows a spherical shell of mass M. The point A is not at the centre but away from the centre of the shell. If a particle of mass m is placed at A, then

42.

The figure shows a spherical shell of mass M. The point A is not at the centre but away from the centre of the shell. If a particle of mass m is placed at A, then

Answer»

The figure shows a spherical shell of mass M. The point A is not at the centre but away from the centre of the shell. If a particle of mass m is placed at A, then

Discussion

43.	If in a pn junction diode, a square input signal of 10 V is applied as shown, then the output signal across R1 will be:
Answer» If in a pn junction diode, a square input signal of 10 V is applied as shown, then the output signal across $R_{1}$ will be:

43.

If in a pn junction diode, a square input signal of 10 V is applied as shown, then the output signal across R1 will be:

Answer»

If in a pn junction diode, a square input signal of 10 V is applied as shown,

then the output signal across $R_{1}$ will be:

Discussion

44.	5 balls of mass 1 kg,2 kg,3 kg,4 kg and 5 kg are tied in a horizontal plane with the massless rod as shown in figure. Balls are rotating about XX′ axis with constant angular velocity ω=10 rad/s. Find the magnitude of angular momentum [in kg m2/s] about axis XX′.
Answer» $5$ balls of mass $1 kg, 2 kg, 3 kg, 4 kg$ and $5 kg$ are tied in a horizontal plane with the massless rod as shown in figure. Balls are rotating about $X X^{'}$ axis with constant angular velocity $ω = 10 rad/s$ . Find the magnitude of angular momentum [in ${kg m}^{2} /s$ ] about axis $X X^{'}$ .

Discussion

45.	A stone with weight W is thrown vertically upward into the air from ground level with initial speed v0. If a constant force f due to air drag acts on the stone throughout its flight. The maximum height attained by the stone is
Answer» A stone with weight $W$ is thrown vertically upward into the air from ground level with initial speed $v_{0}$ . If a constant force $f$ due to air drag acts on the stone throughout its flight. The maximum height attained by the stone is

Discussion

46.	A block of mass 0.18 kg is attached to a spring of force-constant 2 N/m. The coefficient of friction between the block and the floor is 0.1. Initially the block is at rest and the spring is un-stretched. An impulse is given to the block as shown in the figure. The block slides a distance of 0.06 m and comes to rest for the first time. The initial velocity of the block in m/s is v = N / 10. Find N
Answer» A block of mass 0.18 kg is attached to a spring of force-constant 2 N/m. The coefficient of friction between the block and the floor is 0.1. Initially the block is at rest and the spring is un-stretched. An impulse is given to the block as shown in the figure. The block slides a distance of 0.06 m and comes to rest for the first time. The initial velocity of the block in m/s is v = N / 10. Find N

Discussion

47.	A block of mass M has a circular cut with a frictionless surface as shown. The block rests on the horizontal frictionless surface of a fixed table. Initially the right edge of the block is at x=0, in a co-ordinate system fixed to the table. A point mass m is released from rest at the topmost point of the path as shown and it slides down. When the mass loses contact with the block, its position is x and the velocity is v. At that instant, which of the following options is/are correct?
Answer» A block of mass $M$ has a circular cut with a frictionless surface as shown. The block rests on the horizontal frictionless surface of a fixed table. Initially the right edge of the block is at $x = 0$ , in a co-ordinate system fixed to the table. A point mass $m$ is released from rest at the topmost point of the path as shown and it slides down. When the mass loses contact with the block, its position is $x$ and the velocity is $v$ . At that instant, which of the following options is/are correct?

Discussion

48.	The superposition takes place between two waves of frequency f and amplitude a. The total intensity is directly proportional to [MP PMT 1986]
Answer» The superposition takes place between two waves of frequency f and amplitude a. The total intensity is directly proportional to [MP PMT 1986]

48.

The superposition takes place between two waves of frequency f and amplitude a. The total intensity is directly proportional to [MP PMT 1986]

Answer»

The superposition takes place between two waves of frequency f and amplitude a. The total intensity is directly proportional to

[MP PMT 1986]

Discussion

49.	Three particles each of mass m, are situated at the vertices of an equilateral triangle of side length a. The only forces acting on the particles are their mutual gravitational forces. It is desired that each particle moves in a circle while maintaining the original separation a. Find the initial velocity that should be given to each particle and also the time required for the circular motion
Answer» Three particles each of mass m, are situated at the vertices of an equilateral triangle of side length a. The only forces acting on the particles are their mutual gravitational forces. It is desired that each particle moves in a circle while maintaining the original separation a. Find the initial velocity that should be given to each particle and also the time required for the circular motion

Discussion

50.	How does oscillation of a charged body in a magnetic field make elecrromagnetic radiation to travel wth velocity of light?
Answer» How does oscillation of a charged body in a magnetic field make elecrromagnetic radiation to travel wth velocity of light?

Discussion

Explore topic-wise InterviewSolutions in Current Affairs.

Find the resistance of the circuit shown below figure between points A and D.

A projectile is fired with velocity u making angle θ with the horizontal. What is the change in velocity when it is at the highest point

The friction coefficient between the table and the block shown in figure (6-E4) is 0.2. Find the tensions in the two strings.

The same retarding force is applied to stop a train. The train stops after 80 m. If the speed is doubled, then the distance will be

What is the resultant of three coplanar forces 300 N at 0o, 400 N at 30∘ and 400 N at 150∘ with x− axis?

A particle starts from rest with a time-varying acceleration, a=(2t−4). Here t is in s and a in m/s2. After what time (in s) particle comes to rest?

When a tuning fork of frequency 341 is sounded with another tuning fork, six beats per second are heard. When the second tuning fork is loaded with wax and sounded with the first tuning fork, the number of beats is two per second. The natural frequency of the second tuning fork is [MP PET 1989]

A metallic rod of length ′l′ is tied to a string of length 2l and made to rotate with angular speed ω on a horizontal table with one end of the string fixed. If there is a vertical magnetic field ‘B′ in the region, the e.m.f. induced across the ends of the rod is

A particle experiences a constant acceleration for 20 sec after starting from rest. If it travels a distance S1 in the first 10 sec and a distance S2 in the next 10 sec, then

A longitudinal sound wave given by p=5sinπ3(x−400t) (p is in N/m2, x is in metres and t is in seconds) is sent down a closed organ pipe. If the pipe vibrates in its second overtone, the length of the pipe is

(a) Define wavefront. Use Huygens' principle to verify the laws of refraction. (b) How is linearly polarised light obtained by the process of scattering of light ? Find the Brewster angle for air-glass interface, when the refractive index of glass =1.5.

A convex lens of diameter 8.0 cm is used to focus a parallel bam of light of wavelength 620 nm. If the light be focused at a distance of 20 cm from the lens, what would be th eradius of the central bright spot formed?

A balloon which always remains spherical on inflation, is being inflated pumping in 900 cubic cm of gas per second. Find the rate at which the radius of the balloon increases when the radius is 15 cm.

A block of mass m, attached to a spring of spring constant k, oscillates on a smooth horizontal table. The other end of the spring is fixed to a wall. If it has a speed v when the spring is at its natural length, how far will it move on the table before coming to an instantaneous rest?

Eight small drops of equal size are falling through air with a steady velocity of 10 cm/sec. If the drops coalesce, what would be the terminal velocity of the bigger drop?

A pilot of mass 75 kg in a jet aircraft executes a loop with a constant speed of 360 km/hr. If the radius of the loop is 200 m, the force exerted by seat on the pilot at the top of the loop is (Take g=10 m/s2)

∫(t√t+√tt2)dt is equal to

A particle was initially at point at height Re from the earth’s surface The work done to bring this particle to earth’s surface is −XGMem2Re. Find the value of X (m= mass of particle).___

The activity of a radioactive sample is A1 at time t1 and A2 at time t2. If Tav is the average life time of the radioactive sample, then the number of atoms that decay during interval (t2−t1)

In a radioactive element the fraction of initial amount remaining after its mean life time is :

The position x of a particle varies with time (t) as x=at2−bt3. The acceleration of the particle will be equal to zero at time

The linear charge density on a dielectric ring of radius R varies with θ as λ=λ0cosθ2, where λ0 is a constant. Find the potential at the centre of the ring. [in volt]

A body of mass 5 kg is moving along a straight line with a velocity of 2 ms−1. A variable force F started acting on it for a time period of 0.5 s as shown in force - time curve. The final velocity of the block is

Light of frequency 8×1015Hz is incident on a substance of photoelectric work function 6.125 eV. The maximum kinetic energy of the emitted photoelectrons is

The given figure shows the isotherms of a fixed mass of an ideal gas at three temperatures TA,TB and TC then

A certain quantity of heat is given to a wire of length‘L’ and its temperature raises by T. γ is the co – efficient of volume expansion of wire and ‘Y’ is young’s modulus of wire, the energy stored per unit volume in the wire is

The maximum charge that can be given to a conducting sphere [in mC] of radius 1m if the dielectric strength of air is 3×106 V/m. is

Given that the displacement of an oscillating particle is given by y=A sin[Bx + Ct + D]. The dimension formula for ABCD is (where x is displacement and t is time)

In air , a metallic sphere with an internal cavity weighs 40g and in water weighs 20g . the volume of the cavity if the density of material with cavity is 8g/cm^3

A block of mass 100 g slides on a rough horizontal surface. If the speed of the block decreases from 10 m s−1 to 5 m s−1, find the thermal energy developed in the process.

Figure shows a hemisphere and a supported rod. Hemisphere is moving right with a uniform velocity v2 and the end of rod which is in contact with ground is moving left with a velocity v1. The rate at which the angle θ is decreasing will be

Find out acceleration of the block. Initially the block is at rest. μs = 0.5 μK = 0.3

A coin is pushed down tangentially from an angular position θ on a cylindrical surface, with a velocity v as shown in the figure. If the coefficient of friction between the coin and surface is μ, find the tangential acceleration of the coin.

For the spring block arrangement as shown in figure: Given that k1=2k2. If force applied by the first spring on the block is F1 and force applied by the second spring on the block is F2, choose the correct option if the block is in equilibrium with the action of an external force 30 N on the block.

An ideal solenoid of cross-sectional area 10−4 m2 has 500 turns per metre. At the centre of this solenoid, another coil of 100 turns is wrapped closely around it. If the current in the coil changes from 0 to 2 A in 3.14 millisecond, the emf developed in the second coil is

A point P moves in counter-clockwise direction on a circular path as shown in the figure. The movement of 'P' is such that it sweeps out a length s=t3+5, where s is in meters and t is in seconds. The radius of the path is 20 m. The acceleration of 'P' when t = 2 s is nearly

The figure shows a spherical shell of mass M. The point A is not at the centre but away from the centre of the shell. If a particle of mass m is placed at A, then

If in a pn junction diode, a square input signal of 10 V is applied as shown, then the output signal across R1 will be:

5 balls of mass 1 kg,2 kg,3 kg,4 kg and 5 kg are tied in a horizontal plane with the massless rod as shown in figure. Balls are rotating about XX′ axis with constant angular velocity ω=10 rad/s. Find the magnitude of angular momentum [in kg m2/s] about axis XX′.

A stone with weight W is thrown vertically upward into the air from ground level with initial speed v0. If a constant force f due to air drag acts on the stone throughout its flight. The maximum height attained by the stone is

The superposition takes place between two waves of frequency f and amplitude a. The total intensity is directly proportional to [MP PMT 1986]

How does oscillation of a charged body in a magnetic field make elecrromagnetic radiation to travel wth velocity of light?