50278 + Interview Questions in Physics

1.	A pendulum suspended from the ceiling of a train has a period T, when the train is at rest. When the train is accelerating with a uniform acceleration a, the period of oscillation will
Answer» A pendulum suspended from the ceiling of a train has a period T, when the train is at rest. When the train is accelerating with a uniform acceleration a, the period of oscillation will

1.

A pendulum suspended from the ceiling of a train has a period T, when the train is at rest. When the train is accelerating with a uniform acceleration a, the period of oscillation will

Answer»

A pendulum suspended from the ceiling of a train has a period T, when the train is at rest. When the train is accelerating with a uniform acceleration a, the period of oscillation will

Discussion

2.	The smallest division on the main scale of a Vernier callipers is 1 mm and 10 vernier divisions coincide with 9 main scale divisions. While measuring the diameter of a ring, the zero mark of the vernier scale lies between 5.0 cm and 5.1 cm and the eighth division of the vernier scale coincides with a main scale division. The diameter of the ring is :
Answer» The smallest division on the main scale of a Vernier callipers is $1 mm$ and 10 vernier divisions coincide with 9 main scale divisions. While measuring the diameter of a ring, the zero mark of the vernier scale lies between $5.0 cm$ and $5.1 cm$ and the eighth division of the vernier scale coincides with a main scale division. The diameter of the ring is :

Discussion

3.	Unpolarized light with an intensity of I0=16Wm2 is incident on a pair of polarizers. The first polarizer has its transmission axis aligned at 50∘ from the vertical. The second polarizer has its transmission axis aligned at 20∘ from the vertical. What is the intensity of the light when it emerges from the second polarizer?
Answer» Unpolarized light with an intensity of $I_{0} = 16 \frac{W}{m^{2}}$ is incident on a pair of polarizers. The first polarizer has its transmission axis aligned at $50^{\circ}$ from the vertical. The second polarizer has its transmission axis aligned at $20^{\circ}$ from the vertical. What is the intensity of the light when it emerges from the second polarizer?

Discussion

4.	For a projectile, the ratio of maximum height reached to the square of flight time is (g=10ms−2)
Answer» For a projectile, the ratio of maximum height reached to the square of flight time is $(g = 10 m s^{- 2})$

Discussion

5.	A man of mass 50 kg is standing on a platform of mass 200 kg kept on a smooth horizontal surface. The man starts moving on the platform with a velocity 20 km/hr relative to the platform. Find the recoil speed of the platform.
Answer» A man of mass $50 kg$ is standing on a platform of mass $200 kg$ kept on a smooth horizontal surface. The man starts moving on the platform with a velocity $20 km/hr$ relative to the platform. Find the recoil speed of the platform.

Discussion

6.	Three uniform bricks each of length 100 cm and mass m are arranged as shown in figure. The distance of centre of mass of the system of bricks from the wall is
Answer» Three uniform bricks each of length $100 cm$ and mass $m$ are arranged as shown in figure. The distance of centre of mass of the system of bricks from the wall is

Discussion

7.	A body constrained to move in the y - direction is subjected to a force given by →F=(−2^i+15^j+6^k)N. What is the work done by this force in moving the body a distance of 10 m along the y - axis?
Answer» A body constrained to move in the y - direction is subjected to a force given by $\to F = (- 2^i + 15^j + 6^k) N .$ What is the work done by this force in moving the body a distance of $10 m$ along the y - axis?

Discussion

8.	A person travels along a straight road for the first half time with a velocity v1 and the second half time with a velocity v2. Then, the mean or average velocity ¯v is given by
Answer» A person travels along a straight road for the first half time with a velocity $v_{1}$ and the second half time with a velocity $v_{2}$ . Then, the mean or average velocity $¯ v$ is given by

Discussion

9.	An air column in a pipe, which is closed at one end, will be in resonance with a vibrating body of frequency 166 Hz, if the length of the air column is
Answer» An air column in a pipe, which is closed at one end, will be in resonance with a vibrating body of frequency 166 Hz, if the length of the air column is

Discussion

10.	A change in a vector may occur due to the translation of frame of reference. Is the statement correct? Give reason.
Answer» A change in a vector may occur due to the translation of frame of reference. Is the statement correct? Give reason.

Discussion

11.	The energy supply being cut-off, an electric heater element cools down to the temperature of its surroundings, but it will not cool further because
Answer» The energy supply being cut-off, an electric heater element cools down to the temperature of its surroundings, but it will not cool further because

Discussion

12.	A string of negligible mass going over a clamped pulley of mass m supports a block of mass M as shown in the figure. The force on the pulley by the clamp is given by
Answer» A string of negligible mass going over a clamped pulley of mass m supports a block of mass M as shown in the figure. The force on the pulley by the clamp is given by

12.

A string of negligible mass going over a clamped pulley of mass m supports a block of mass M as shown in the figure. The force on the pulley by the clamp is given by

Answer»

A string of negligible mass going over a clamped pulley of mass m supports a block of mass M as shown in the figure. The force on the pulley by the clamp is given by

Discussion

13.	Certain neutron stars are believed to be rotating at about 1 rec/sec. If such a star has a radius of 20 km, the acceleration of an object on the equator of the star will be
Answer» Certain neutron stars are believed to be rotating at about 1 rec/sec. If such a star has a radius of 20 km, the acceleration of an object on the equator of the star will be

Discussion

14.	If the distance between two masses is doubled, the gravitational attraction between them
Answer» If the distance between two masses is doubled, the gravitational attraction between them

Discussion

15.	The distance of a planet from the sun is 5 times the distance between the earth and the sun. The Time period of the planet is:
Answer» The distance of a planet from the sun is $5$ times the distance between the earth and the sun. The Time period of the planet is:

Discussion

16.	A diametrical tunnel is dug across the earth. A ball is dropped into the tunnel from one side. The velocity of the ball when it reaches the centre of the earth is
Answer» A diametrical tunnel is dug across the earth. A ball is dropped into the tunnel from one side. The velocity of the ball when it reaches the centre of the earth is

Discussion

17.	The extension in a uniform rod of length l, mass m, cross sectional area A and young's modulus Y when it is suspended vertically at one end is
Answer» The extension in a uniform rod of length $l$ , mass $m$ , cross sectional area $A$ and young's modulus $Y$ when it is suspended vertically at one end is

Discussion

18.	A liquid is coming out from a vertical tube. The relation between the weight of the drop W, surface tension of the liquid T and radius of the tube r is given by, if the angle of contact is zero
Answer» A liquid is coming out from a vertical tube. The relation between the weight of the drop W, surface tension of the liquid T and radius of the tube r is given by, if the angle of contact is zero

Discussion

19.	The potential difference applied across a given resistor is altered so that the heat produced per second increases by a factor of 9. By what factor does the applied potential difference change? (b) In the figure shown, an ammeter A and a resistor of 4Ω are connected to the terminals of the source. The emf of the source is 12 V having the internal resistance of 2 Ω Calculate the voltmeter and ammeter readings
Answer» The potential difference applied across a given resistor is altered so that the heat produced per second increases by a factor of 9. By what factor does the applied potential difference change? (b) In the figure shown, an ammeter A and a resistor of 4 $Ω$ are connected to the terminals of the source. The emf of the source is 12 V having the internal resistance of 2 $Ω$ Calculate the voltmeter and ammeter readings

Discussion

20.	Two waves represented by equation, y1=2sin(πt−0.1x) and y2=2sin(πt−0.1x+ϕ) are superimposed. If the resultant wave has a maximum amplitude equal to 4 cm, the value of ϕ is :
Answer» Two waves represented by equation, $y_{1} = 2 sin (π t - 0.1 x)$ and $y_{2} = 2 sin (π t - 0.1 x + ϕ)$ are superimposed. If the resultant wave has a maximum amplitude equal to $4 cm$ , the value of $ϕ$ is :

Discussion

21.	A boy riding on a bicycle going at 12 km h−1 towards a vertical wall whistles at his dog on the ground. If the frequency of the whistle is 1600 Hz and the speed of sound in air is 330 m s−1, find (a) the frequency of the whistle as received by the wall (b) the frequency of the reflected whistle as received by the boy.
Answer» A boy riding on a bicycle going at 12 km $h^{- 1}$ towards a vertical wall whistles at his dog on the ground. If the frequency of the whistle is 1600 Hz and the speed of sound in air is $330 m s^{- 1}$ , find (a) the frequency of the whistle as received by the wall (b) the frequency of the reflected whistle as received by the boy.

Discussion

22.	A metal wire PQ of mass 10 g lies at rest on two horizontal metal rails separated by 4.90 cm (figure 34 - E9). A vertically downward magnetic field of magnitude 0.800 T exists in the space. The resistance of the circuit is slowly decreased and it is found that when the resistance goes below 20.0 Ω, the wire PQ starts sliding on the rails. Find the coefficient of friction.
Answer» A metal wire PQ of mass 10 g lies at rest on two horizontal metal rails separated by 4.90 cm (figure 34 - E9). A vertically downward magnetic field of magnitude 0.800 T exists in the space. The resistance of the circuit is slowly decreased and it is found that when the resistance goes below 20.0 $Ω$ , the wire PQ starts sliding on the rails. Find the coefficient of friction.

22.

A metal wire PQ of mass 10 g lies at rest on two horizontal metal rails separated by 4.90 cm (figure 34 - E9). A vertically downward magnetic field of magnitude 0.800 T exists in the space. The resistance of the circuit is slowly decreased and it is found that when the resistance goes below 20.0 Ω, the wire PQ starts sliding on the rails. Find the coefficient of friction.

Answer»

A metal wire PQ of mass 10 g lies at rest on two horizontal metal rails separated by 4.90 cm (figure 34 - E9). A vertically downward magnetic field of magnitude 0.800 T exists in the space. The resistance of the circuit is slowly decreased and it is found that when the resistance goes below 20.0 $Ω$ , the wire PQ starts sliding on the rails. Find the coefficient of friction.

Discussion

23.	Two small spheres, each having a mass of 20 g, are suspended from a common point by two insultating strings of length 40 cm each. The spehres are identically charged and the separation between the balls at equilibrium is found to be 4 cm. Find the charge on each spehere.
Answer» Two small spheres, each having a mass of 20 g, are suspended from a common point by two insultating strings of length 40 cm each. The spehres are identically charged and the separation between the balls at equilibrium is found to be 4 cm. Find the charge on each spehere.

Discussion

24.	A square of side 3 cm is placed at a distance of 25 cm from a concave mirror of focal length 10 cm. The centre of the square is at the axis of the mirror and the plane is normal to the axis. The area enclosed by the image of the wire is
Answer» A square of side 3 cm is placed at a distance of 25 cm from a concave mirror of focal length 10 cm. The centre of the square is at the axis of the mirror and the plane is normal to the axis. The area enclosed by the image of the wire is

Discussion

25.	A calorimeter contains 50 g of water at 50^0 C. The temperature falls to 450 C in 10 minutes. When the calorimeter contains 100 g of water at 500 C, it takes 18 minutes for the temperature to become 450 C. Find the water equivalent of the calorimeter.
Answer» A calorimeter contains 50 g of water at 50^0 C. The temperature falls to $45^{0}$ C in 10 minutes. When the calorimeter contains 100 g of water at $50^{0}$ C, it takes 18 minutes for the temperature to become $45^{0}$ C. Find the water equivalent of the calorimeter.

Discussion

26.	A short magnet oscillates in an oscillation magnetometer with a time period of 0.10 s where the earth's horizontal magnetic field is 24μT. A downward current of 18 A is established in a vertical wire placed 20 cm east of the magnet. Find the new time period.
Answer» A short magnet oscillates in an oscillation magnetometer with a time period of 0.10 s where the earth's horizontal magnetic field is $24 μ T$ . A downward current of 18 A is established in a vertical wire placed 20 cm east of the magnet. Find the new time period.

Discussion

27.	Two infinitely long parallel wires having linear charge densities λ1 and λ2 respectively are placed at a distance of R metres. The force per unit length on either wire will be (K=14πϵ0)
Answer» Two infinitely long parallel wires having linear charge densities $λ_{1}$ and $λ_{2}$ respectively are placed at a distance of R metres. The force per unit length on either wire will be $(K = \frac{1}{4 π ϵ_{0}})$

Discussion

28.	A body of mass 2 kg moving with a velocity (^i+2^j−3^k) ms−1 collides with another body of mass 3 kg moving with a velocity (2^i+^j+^k) in ms−1. If they stick together, the velocity in ms−1 of the composite body is
Answer» A body of mass 2 kg moving with a velocity $(^i + 2^j - 3^k) m s^{- 1}$ collides with another body of mass 3 kg moving with a velocity $(2^i +^j +^k)$ in $m s^{- 1}$ . If they stick together, the velocity in $m s^{- 1}$ of the composite body is

Discussion

29.	A body of mass m is thrown at an angle θ to the horizontal with the initial velocity u. Find the instantaneous power of gravity as function of time.
Answer» A body of mass m is thrown at an angle θ to the horizontal with the initial velocity u. Find the instantaneous power of gravity as function of time.

Discussion

30.	Five forces −→F1, −→F2, −→F3, −→F4 and −→F5 are acting on a particle of mass 2.0 kg so that it is moving with 4 m/s2 in east direction. If −→F1 force is removed then the acceleration becomes 7 m/s2 in north. Find the magnitude of acceleration of the block if only −→F1 is acting.
Answer» Five forces $_{1},_{2},_{3},_{4}$ and $_{5}$ are acting on a particle of mass $2.0 kg$ so that it is moving with $4 {m/s}^{2}$ in east direction. If $_{1}$ force is removed then the acceleration becomes $7 {m/s}^{2}$ in north. Find the magnitude of acceleration of the block if only $_{1}$ is acting.

Discussion

31.	Uniform electric field of 10NC-1 exist in the vertically downward direction find the increase is electric potential as one goes up through a height of 50 cm
Answer» Uniform electric field of 10NC^-1 exist in the vertically downward direction find the increase is electric potential as one goes up through a height of 50 cm

Discussion

32.	The instantaneous displacement of a simple pendulum oscillator is given by x=Acos (wt+π/4). It's speed will be maximum at time
Answer» The instantaneous displacement of a simple pendulum oscillator is given by x=Acos (wt+π/4). It's speed will be maximum at time

Discussion

33.	If we add impurities in semiconductor than the number of electrons in conduction band increase is this imply that the semiconductor with impurities will conduct more electricity? Or the electricity remains same?
Answer» If we add impurities in semiconductor than the number of electrons in conduction band increase is this imply that the semiconductor with impurities will conduct more electricity? Or the electricity remains same?

Discussion

34.	A force of 5×103 N is applied on the rod of length 1 m. Find the linear strain if elongation in the rod is 10 mm.
Answer» A force of $5 \times 10^{3} N$ is applied on the rod of length $1 m$ . Find the linear strain if elongation in the rod is $10 mm$ .

Discussion

35.	State the difference between mass and weight of a body.
Answer» State the difference between mass and weight of a body.

Discussion

36.	Torque acting on a current carrying coil is maximum when :
Answer» Torque acting on a current carrying coil is maximum when :

Discussion

37.	Derive the relation between momentum and impulse
Answer» Derive the relation between momentum and impulse

Discussion

38.	How this relation formed surface energy/area=surface tension? In byju's video they derived that surface energy =Surface tension . Please explain I am confused .
Answer» How this relation formed surface energy/area=surface tension? In byju's video they derived that surface energy =Surface tension . Please explain I am confused .

Discussion

39.	If we keep two similar loops made up of copper and constantan in a magnetic field for same amount of time, in which loop the induced e.m.f will be greater.
Answer» If we keep two similar loops made up of copper and constantan in a magnetic field for same amount of time, in which loop the induced e.m.f will be greater.

Discussion

40.	Why did the leaves of the electroscope collapse on touching?
Answer» Why did the leaves of the electroscope collapse on touching?

Discussion

41.	If pulley shown in the diagram are smooth and massless and a1 and a2 are acceleration of blocks of mass 4 kg and 8 kg respectively, then
Answer» If pulley shown in the diagram are smooth and massless and $a_{1}$ and $a_{2}$ are acceleration of blocks of mass $4 kg$ and $8 kg$ respectively, then

Discussion

42.	A swimmer wishes to cross a river 500 m wide flowing at a rate u. His speed with respect to still water is V. For this, he makes an angle θ with the vertical to the direction of flow of the river as shown. In order to cross the river in minimum time, the value θ of in degrees should be
Answer» A swimmer wishes to cross a river $500 m$ wide flowing at a rate $u$ . His speed with respect to still water is $V$ . For this, he makes an angle $θ$ with the vertical to the direction of flow of the river as shown. In order to cross the river in minimum time, the value $θ$ of in degrees should be

Discussion

43.	If two mirrors are kept at 600 to each other, then the number of images formed by them is
Answer» If two mirrors are kept at $60^{0}$ to each other, then the number of images formed by them is

Discussion

44.	The air of density ρ and moving with a velocity v strikes perpendicularly the inclined surface of area A, of a wedge kept on a horizontal surface. The mass of the wedge is m. Assuming the collisions to be perfectly inelastic, the minimum value of the coefficient of friction between the wedge and the ground so that the wedge does not move is (Assume mass of particles of air is negligible)
Answer» The air of density ρ and moving with a velocity v strikes perpendicularly the inclined surface of area A, of a wedge kept on a horizontal surface. The mass of the wedge is m. Assuming the collisions to be perfectly inelastic, the minimum value of the coefficient of friction between the wedge and the ground so that the wedge does not move is (Assume mass of particles of air is negligible)

Discussion

45.	In the figure shown, find the acceleration of the block B. Assume all surfaces to be smooth.
Answer» In the figure shown, find the acceleration of the block $B$ . Assume all surfaces to be smooth.

Discussion

46.	An electric fan has blades of length 30 cm as measured from the axis of rotation. If the fan is rotating at 1200 r.p.m. The acceleration of a point on the tip of the blade is about
Answer» An electric fan has blades of length 30 cm as measured from the axis of rotation. If the fan is rotating at 1200 r.p.m. The acceleration of a point on the tip of the blade is about

Discussion

47.	The given figure shows the shape of part of a long string in which transverse waves are produced by attaching one end of the string to tuning fork of frequency 250 Hz. What is the velocity of the waves?
Answer» The given figure shows the shape of part of a long string in which transverse waves are produced by attaching one end of the string to tuning fork of frequency 250 Hz. What is the velocity of the waves?

Discussion

48.	A solid uniform cylinder of mass M performs small oscillations in the horizontal plane if slightly displaced from its mean position as shown in the figure. Initially, the springs are at their natural lengths and the cylinder does not slip on the ground during oscillations due to friction between the ground and cylinder. The force constant of each spring is k. What is the time period of this oscillation?
Answer» A solid uniform cylinder of mass $M$ performs small oscillations in the horizontal plane if slightly displaced from its mean position as shown in the figure. Initially, the springs are at their natural lengths and the cylinder does not slip on the ground during oscillations due to friction between the ground and cylinder. The force constant of each spring is $k$ . What is the time period of this oscillation?

Discussion

49.	A sample of helium gas contains 50 atoms, following table gives number of molecules (N) moving with definite speed (v); rms (root mean square) speed of sample is approximately v6.08.09.011.013.0N10161194
Answer» A sample of helium gas contains 50 atoms, following table gives number of molecules ( $N$ ) moving with definite speed ( $v$ ); rms (root mean square) speed of sample is approximately $\begin{matrix} v & 6.0 & 8.0 & 9.0 & 11.0 & 13.0 N & 10 & 16 & 11 & 9 & 4 \end{matrix}$

Discussion

50.	Consider the disc kept on a rough horizontal surface as shown in the diagram. If a horizontal force ‘F’ has to be applied such that the disc starts pure rolling. What should be the
Answer» Consider the disc kept on a rough horizontal surface as shown in the diagram. If a horizontal force ‘F’ has to be applied such that the disc starts pure rolling. What should be the

50.

Consider the disc kept on a rough horizontal surface as shown in the diagram. If a horizontal force ‘F’ has to be applied such that the disc starts pure rolling. What should be the

Answer»

Consider the disc kept on a rough horizontal surface as shown in the diagram. If a horizontal force ‘F’ has to be applied such that the disc starts pure rolling. What should be the

Discussion

Explore topic-wise InterviewSolutions in Current Affairs.

A pendulum suspended from the ceiling of a train has a period T, when the train is at rest. When the train is accelerating with a uniform acceleration a, the period of oscillation will

For a projectile, the ratio of maximum height reached to the square of flight time is (g=10ms−2)

A man of mass 50 kg is standing on a platform of mass 200 kg kept on a smooth horizontal surface. The man starts moving on the platform with a velocity 20 km/hr relative to the platform. Find the recoil speed of the platform.

Three uniform bricks each of length 100 cm and mass m are arranged as shown in figure. The distance of centre of mass of the system of bricks from the wall is

A body constrained to move in the y - direction is subjected to a force given by →F=(−2^i+15^j+6^k)N. What is the work done by this force in moving the body a distance of 10 m along the y - axis?

A person travels along a straight road for the first half time with a velocity v1 and the second half time with a velocity v2. Then, the mean or average velocity ¯v is given by

An air column in a pipe, which is closed at one end, will be in resonance with a vibrating body of frequency 166 Hz, if the length of the air column is

A change in a vector may occur due to the translation of frame of reference. Is the statement correct? Give reason.

The energy supply being cut-off, an electric heater element cools down to the temperature of its surroundings, but it will not cool further because

A string of negligible mass going over a clamped pulley of mass m supports a block of mass M as shown in the figure. The force on the pulley by the clamp is given by

Certain neutron stars are believed to be rotating at about 1 rec/sec. If such a star has a radius of 20 km, the acceleration of an object on the equator of the star will be

If the distance between two masses is doubled, the gravitational attraction between them

The distance of a planet from the sun is 5 times the distance between the earth and the sun. The Time period of the planet is:

A diametrical tunnel is dug across the earth. A ball is dropped into the tunnel from one side. The velocity of the ball when it reaches the centre of the earth is

The extension in a uniform rod of length l, mass m, cross sectional area A and young's modulus Y when it is suspended vertically at one end is

A liquid is coming out from a vertical tube. The relation between the weight of the drop W, surface tension of the liquid T and radius of the tube r is given by, if the angle of contact is zero

Two waves represented by equation, y1=2sin(πt−0.1x) and y2=2sin(πt−0.1x+ϕ) are superimposed. If the resultant wave has a maximum amplitude equal to 4 cm, the value of ϕ is :

Two small spheres, each having a mass of 20 g, are suspended from a common point by two insultating strings of length 40 cm each. The spehres are identically charged and the separation between the balls at equilibrium is found to be 4 cm. Find the charge on each spehere.

A square of side 3 cm is placed at a distance of 25 cm from a concave mirror of focal length 10 cm. The centre of the square is at the axis of the mirror and the plane is normal to the axis. The area enclosed by the image of the wire is

A calorimeter contains 50 g of water at 50^0 C. The temperature falls to 450 C in 10 minutes. When the calorimeter contains 100 g of water at 500 C, it takes 18 minutes for the temperature to become 450 C. Find the water equivalent of the calorimeter.

A short magnet oscillates in an oscillation magnetometer with a time period of 0.10 s where the earth's horizontal magnetic field is 24μT. A downward current of 18 A is established in a vertical wire placed 20 cm east of the magnet. Find the new time period.

Two infinitely long parallel wires having linear charge densities λ1 and λ2 respectively are placed at a distance of R metres. The force per unit length on either wire will be (K=14πϵ0)

A body of mass 2 kg moving with a velocity (^i+2^j−3^k) ms−1 collides with another body of mass 3 kg moving with a velocity (2^i+^j+^k) in ms−1. If they stick together, the velocity in ms−1 of the composite body is

A body of mass m is thrown at an angle θ to the horizontal with the initial velocity u. Find the instantaneous power of gravity as function of time.

Uniform electric field of 10NC-1 exist in the vertically downward direction find the increase is electric potential as one goes up through a height of 50 cm

The instantaneous displacement of a simple pendulum oscillator is given by x=Acos (wt+π/4). It's speed will be maximum at time

If we add impurities in semiconductor than the number of electrons in conduction band increase is this imply that the semiconductor with impurities will conduct more electricity? Or the electricity remains same?

A force of 5×103 N is applied on the rod of length 1 m. Find the linear strain if elongation in the rod is 10 mm.

State the difference between mass and weight of a body.

Torque acting on a current carrying coil is maximum when :

Derive the relation between momentum and impulse

How this relation formed surface energy/area=surface tension? In byju's video they derived that surface energy =Surface tension . Please explain I am confused .

If we keep two similar loops made up of copper and constantan in a magnetic field for same amount of time, in which loop the induced e.m.f will be greater.

Why did the leaves of the electroscope collapse on touching?

If pulley shown in the diagram are smooth and massless and a1 and a2 are acceleration of blocks of mass 4 kg and 8 kg respectively, then

A swimmer wishes to cross a river 500 m wide flowing at a rate u. His speed with respect to still water is V. For this, he makes an angle θ with the vertical to the direction of flow of the river as shown. In order to cross the river in minimum time, the value θ of in degrees should be

If two mirrors are kept at 600 to each other, then the number of images formed by them is

In the figure shown, find the acceleration of the block B. Assume all surfaces to be smooth.

An electric fan has blades of length 30 cm as measured from the axis of rotation. If the fan is rotating at 1200 r.p.m. The acceleration of a point on the tip of the blade is about

The given figure shows the shape of part of a long string in which transverse waves are produced by attaching one end of the string to tuning fork of frequency 250 Hz. What is the velocity of the waves?

A sample of helium gas contains 50 atoms, following table gives number of molecules (N) moving with definite speed (v); rms (root mean square) speed of sample is approximately v6.08.09.011.013.0N10161194

Consider the disc kept on a rough horizontal surface as shown in the diagram. If a horizontal force ‘F’ has to be applied such that the disc starts pure rolling. What should be the