50278 + Interview Questions in Physics

1.	Three charges Q,+q and +q are placed at the vertices of a right angled isosceles triangle as shown in figure. The net electrostatic energy of the configuration is zero, if Q is equal to
Answer» Three charges $Q, + q$ and $+ q$ are placed at the vertices of a right angled isosceles triangle as shown in figure. The net electrostatic energy of the configuration is zero, if $Q$ is equal to

Discussion

2.	A ball rolls off the top of a stairway horizontally with a velocity of 4.5 ms−1. Each step is 0.2 m high and 0.3 m wide. If g is 10 ms−2, then the ball will strike the nth step where n is equal to
Answer» A ball rolls off the top of a stairway horizontally with a velocity of $4.5 {ms}^{- 1}$ . Each step is $0.2 m$ high and $0.3 m$ wide. If $g$ is $10 {ms}^{- 2}$ , then the ball will strike the $n^{t h}$ step where $n$ is equal to

Discussion

3.	Given that, force varies with position(x) as F=1+2x+3x2+4x3+5x4, when x changes from 0 to 5 m, then work done by the force is
Answer» Given that, force varies with position $(x)$ as $F = 1 + 2 x + 3 x^{2} + 4 x^{3} + 5 x^{4}$ , when $x$ changes from $0$ to $5 m$ , then work done by the force is

Discussion

4.	What is avalanche effect
Answer» What is avalanche effect

Discussion

5.	What is the difference between a charge and a free electron
Answer» What is the difference between a charge and a free electron

Discussion

6.	A football is kicked with a velocity of 20 m/s at an angle of 45∘ with the horizontal. Find the time taken by the ball (in sec) to strike the ground. Give answer correct to 1 decimal place ___
Answer» A football is kicked with a velocity of 20 m/s at an angle of $45^{\circ}$ with the horizontal. Find the time taken by the ball (in sec) to strike the ground. Give answer correct to 1 decimal place ___

Discussion

7.	Kerosene oil is flowing through a pipe having constant cross section area with diameter 2.5 cm, at a rate of 10 litre/sec. The height of bottom and top end is 2 m and 8 m respectively from the datum line. Find the pressure at the lower end, if the pressure at the other end is 25×104 N/m2. (Density of kerosene =850 kg/m3)
Answer» Kerosene oil is flowing through a pipe having constant cross section area with diameter $2.5 cm$ , at a rate of $10 litre/sec$ . The height of bottom and top end is $2 m$ and $8 m$ respectively from the datum line. Find the pressure at the lower end, if the pressure at the other end is $25 \times 10^{4} {N/m}^{2}$ . (Density of kerosene $= 850 {kg/m}^{3})$

Discussion

8.	Distance between a frog and an insect on a horizontal plane is 9 m. Frog can jump with a maximum speed of √10 m/s . Minimum number of jumps required by the frog to catch the insect is (Take g=10 m/s2)
Answer» Distance between a frog and an insect on a horizontal plane is $9 m$ . Frog can jump with a maximum speed of $\sqrt{10} m / s$ . Minimum number of jumps required by the frog to catch the insect is (Take $g = 10 m / s^{2}$ )

Discussion

9.	The mass M shown in the figure oscillates in simple harmonic motion with amplitude A. The amplitude of the point P is
Answer» The mass M shown in the figure oscillates in simple harmonic motion with amplitude A. The amplitude of the point P is

9.

The mass M shown in the figure oscillates in simple harmonic motion with amplitude A. The amplitude of the point P is

Answer»

The mass M shown in the figure oscillates in simple harmonic motion with amplitude A. The amplitude of the point P is

Discussion

10.	A simple pendulum has a time period exactly 2s when used in a laboratory at north pole. What will be the time period if the same pendulum is used in a laboratory at equator? Account for the earth's rotation only. Take g Gmr2 = 9.8 m/s2 and radius of earth = 6400 km.
Answer» A simple pendulum has a time period exactly 2s when used in a laboratory at north pole. What will be the time period if the same pendulum is used in a laboratory at equator? Account for the earth's rotation only. Take g $\frac{G m}{r^{2}}$ = 9.8 m/s² and radius of earth = 6400 km.

Discussion

11.	A block of mass 20 kg is suspended through two light spring balances as shown in figure. Calculate the reading of spring balance (1) and (2) respectively.
Answer» A block of mass $20 kg$ is suspended through two light spring balances as shown in figure. Calculate the reading of spring balance $(1)$ and $(2)$ respectively.

Discussion

12.	A body is moving with a constant speed v in a circle of radius r. What is the angular acceleration?
Answer» A body is moving with a constant speed v in a circle of radius r. What is the angular acceleration?

Discussion

13.	A double convex thin lens made of glass (refractive index 1.5) has both radii of curvature of magnitude 20 cm. Incident light rays parallel to the axis of the lens will converge at distance L such that
Answer» A double convex thin lens made of glass (refractive index $1.5$ ) has both radii of curvature of magnitude $20 c m$ . Incident light rays parallel to the axis of the lens will converge at distance $L$ such that

Discussion

14.	If mean wavelength of light radiated by 100 W lamp is 5000 Å, then the number of photons radiated per second are
Answer» If mean wavelength of light radiated by 100 W lamp is 5000 Å, then the number of photons radiated per second are

Discussion

15.	What is the maximum potential difference that can be detected by a potentiometer?
Answer» What is the maximum potential difference that can be detected by a potentiometer?

Discussion

16.	According to sign convention, which of the distances measured in the figure are considered to be negative?
Answer» According to sign convention, which of the distances measured in the figure are considered to be negative?

Discussion

17.	Consider the situation of the previous problem.Suppose the block of mass m1 is pulled by a constant force F1 and the other block is pulled by a constant force F2.Find the maximum elongation that the spring will suffer.
Answer» Consider the situation of the previous problem.Suppose the block of mass $m_{1}$ is pulled by a constant force $F_{1}$ and the other block is pulled by a constant force $F_{2}$ .Find the maximum elongation that the spring will suffer.

Discussion

18.	A wire is bent in th eform of a regular hexagon and a total cahrge q is distributed uniformly on it. What is the electric field at the centre? you may answer this part without making any numerical calculations.
Answer» A wire is bent in th eform of a regular hexagon and a total cahrge q is distributed uniformly on it. What is the electric field at the centre? you may answer this part without making any numerical calculations.

Discussion

19.	For the force-displacement graph for a particle is as shown below. If the particle has mass of 2 kg and has initial velocity of 2 m/s, calculate final kinetic energy of particle, when it displaces from x=1 m to x=5 m.
Answer» For the force-displacement graph for a particle is as shown below. If the particle has mass of $2 kg$ and has initial velocity of $2 m/s$ , calculate final kinetic energy of particle, when it displaces from $x = 1 m$ to $x = 5 m$ .

Discussion

20.	A circular hoop of mass m and radius R rests flat on a horizontal frictionless surface. A bullet, also of mass m and moving with a velocity v, strikes the hoop and gets embedded in it. The thickness of the hoop is much smaller than R. The angular velocity with which the system rotates after the bullet strikes the hoop is:
Answer» A circular hoop of mass m and radius R rests flat on a horizontal frictionless surface. A bullet, also of mass m and moving with a velocity v, strikes the hoop and gets embedded in it. The thickness of the hoop is much smaller than R. The angular velocity with which the system rotates after the bullet strikes the hoop is:

20.

A circular hoop of mass m and radius R rests flat on a horizontal frictionless surface. A bullet, also of mass m and moving with a velocity v, strikes the hoop and gets embedded in it. The thickness of the hoop is much smaller than R. The angular velocity with which the system rotates after the bullet strikes the hoop is:

Answer»

A circular hoop of mass m and radius R rests flat on a horizontal frictionless surface. A bullet, also of mass m and moving with a velocity v, strikes the hoop and gets embedded in it. The thickness of the hoop is much smaller than R. The angular velocity with which the system rotates after the bullet strikes the hoop is:

Discussion

21.	The angular velocity and the amplitude of a simple pendulum is ω and a respectively. At a displacement X from the mean position if its kinetic energy is T and potential energy is V, then the ratio of T to V is [CBSE PMT 1991]
Answer» The angular velocity and the amplitude of a simple pendulum is ω and a respectively. At a displacement X from the mean position if its kinetic energy is T and potential energy is V, then the ratio of T to V is [CBSE PMT 1991]

21.

The angular velocity and the amplitude of a simple pendulum is ω and a respectively. At a displacement X from the mean position if its kinetic energy is T and potential energy is V, then the ratio of T to V is [CBSE PMT 1991]

Answer»

The angular velocity and the amplitude of a simple pendulum is ω and a respectively. At a displacement X from the mean position if its kinetic energy is T and potential energy is V, then the ratio of T to V is

[CBSE PMT 1991]

Discussion

22.	Silicon doped with Arsenic is an example of:
Answer» Silicon doped with Arsenic is an example of:

Discussion

23.	The electric field intensity due to a sphere (solid or hollow) at an external point varies as-
Answer» The electric field intensity due to a sphere (solid or hollow) at an external point varies as-

Discussion

24.	A man of mass M having a bag of mass m slips from the roof of a tall building of height H and starts falling vertically (figure).When at a height h from the ground, he notices that the ground below him is pretty hard, but there is a pond at a horizontal distance x from the line of fall. In order to save himself he throws the bag horizontally (with respect to himself) in the direction opposite to the pond. Calculate the minimum horizontal velocity imparted to the bag so that the man lands in the water.
Answer» A man of mass M having a bag of mass m slips from the roof of a tall building of height H and starts falling vertically (figure).When at a height h from the ground, he notices that the ground below him is pretty hard, but there is a pond at a horizontal distance x from the line of fall. In order to save himself he throws the bag horizontally (with respect to himself) in the direction opposite to the pond. Calculate the minimum horizontal velocity imparted to the bag so that the man lands in the water.

24.

A man of mass M having a bag of mass m slips from the roof of a tall building of height H and starts falling vertically (figure).When at a height h from the ground, he notices that the ground below him is pretty hard, but there is a pond at a horizontal distance x from the line of fall. In order to save himself he throws the bag horizontally (with respect to himself) in the direction opposite to the pond. Calculate the minimum horizontal velocity imparted to the bag so that the man lands in the water.

Answer»

A man of mass M having a bag of mass m slips from the roof of a tall building of height H and starts falling vertically (figure).When at a height h from the ground, he notices that the ground below him is pretty hard, but there is a pond at a horizontal distance x from the line of fall. In order to save himself he throws the bag horizontally (with respect to himself) in the direction opposite to the pond. Calculate the minimum horizontal velocity imparted to the bag so that the man lands in the water.

Discussion

25.	A solid sphere of density ρ and radius R is floating in a liquid of density σ with half its volume submerged. When the sphere pressed down slightly and released, it executes simple harmonic motion of time period T. If viscous effect is ignored, then
Answer» A solid sphere of density $ρ$ and radius R is floating in a liquid of density $σ$ with half its volume submerged. When the sphere pressed down slightly and released, it executes simple harmonic motion of time period T. If viscous effect is ignored, then

Discussion

26.	Water flows through a frictionless duct with a cross-section varying as shown in fig. Pressure p at points along the axis is represented by
Answer» Water flows through a frictionless duct with a cross-section varying as shown in fig. Pressure p at points along the axis is represented by

Discussion

27.	The ratio of the longest to the shortest wavelength in the Balmer series of Hydrogen spectrum is
Answer» The ratio of the longest to the shortest wavelength in the Balmer series of Hydrogen spectrum is

Discussion

28.	If charge on left of the 5 μF capacitor in the circuit segment shown in the figure is - 18 μC. The charge on the right plate of 3μF capacitor is
Answer» If charge on left of the 5 $μ F$ capacitor in the circuit segment shown in the figure is - 18 $μ C$ . The charge on the right plate of $3 μ F$ capacitor is

28.

If charge on left of the 5 μF capacitor in the circuit segment shown in the figure is - 18 μC. The charge on the right plate of 3μF capacitor is

Answer»

If charge on left of the 5 $μ F$ capacitor in the circuit segment shown in the figure is - 18 $μ C$ . The charge on the right plate of $3 μ F$ capacitor is

Discussion

29.	The charge on 3μF capacitor shown in the figure is:
Answer» The charge on $3 μ F$ capacitor shown in the figure is:

Discussion

30.	A car travels first half distance with uniform speed of 60 km/hr. What should be its uniform speed (in km/hr) for the second half of the distance so that its average speed over the entire journey becomes 90 km/hr.
Answer» A car travels first half distance with uniform speed of $60 km/hr$ . What should be its uniform speed (in $km/hr$ ) for the second half of the distance so that its average speed over the entire journey becomes $90 km/hr$ .

Discussion

31.	For the system shown in the figure, the cylinder on left has a mass (M) of 25 kg, cross-sectional area 20 cm2 and thickness 5 cm. It is connected to a spring of spring constant 1880 N/m. The piston on the right has mass m(=5 kg) and cross-sectional area 4 cm2. Initially heights of water column in both cylinders are equal and pistons are in equilibrium. The minimum mass m′ (in kg) to be kept on m so that water just spills out from the left is (g=10 m/s2)
Answer» For the system shown in the figure, the cylinder on left has a mass $(M)$ of $25 kg$ , cross-sectional area $20 {cm}^{2}$ and thickness $5 cm$ . It is connected to a spring of spring constant $1880 N/m$ . The piston on the right has mass $m (= 5 kg)$ and cross-sectional area $4 {cm}^{2}$ . Initially heights of water column in both cylinders are equal and pistons are in equilibrium. The minimum mass $m^{'}$ (in $kg)$ to be kept on $m$ so that water just spills out from the left is $(g = 10 {m/s}^{2})$

Discussion

32.	A uniform disc of radius R having charge Q distributed uniformly all over its surface is placed on a smooth horizontal surface. A magnetic field, B = kxt2, where k is a constant, x is the distance (in metre) from the centre of the disc and t is the time (in second), is switched on perpendicular to the plane of the disc. Find the torque (in N-m) acting on the disc after 15 sec. (Take 4kQ = 1 and R = 1m)
Answer» A uniform disc of radius R having charge Q distributed uniformly all over its surface is placed on a smooth horizontal surface. A magnetic field, B = $k x t^{2}$ , where k is a constant, x is the distance (in metre) from the centre of the disc and t is the time (in second), is switched on perpendicular to the plane of the disc. Find the torque (in N-m) acting on the disc after 15 sec. (Take 4kQ = 1 and R = 1m)

Discussion

33.	A particle of charge equal to that of an electron, -e and mass 208 times of the mass of the electron (called a mu-meson) moves in a circular orbit around a nucleus of charge +3e. (Take the mass of the nucleus to be infinite). Assume that the Bohr model of the atom is applicable to this system. If the value of n for which the radius of the orbit is approximately the same as that of the first Bohr orbit for the hydrogen atom, then the value of n4 rounded off to nearest integer is
Answer» A particle of charge equal to that of an electron, -e and mass 208 times of the mass of the electron (called a mu-meson) moves in a circular orbit around a nucleus of charge +3e. (Take the mass of the nucleus to be infinite). Assume that the Bohr model of the atom is applicable to this system. If the value of n for which the radius of the orbit is approximately the same as that of the first Bohr orbit for the hydrogen atom, then the value of $\frac{n}{4}$ rounded off to nearest integer is

Discussion

34.	Water flows through a horizontal tube of variable cross section figure. The area of cross section at A and B are 4 mm2 and 2mm2 respectively. If 1 cc of water enters per second through A, find (a) the speed of water at A, (b) the speed of water at B and (c) the pressure difference PA—PB.
Answer» Water flows through a horizontal tube of variable cross section figure. The area of cross section at A and B are 4 $m m^{2}$ and 2 $m m^{2}$ respectively. If 1 cc of water enters per second through A, find (a) the speed of water at A, (b) the speed of water at B and (c) the pressure difference $P_{A} — P_{B}$ .

34.

Water flows through a horizontal tube of variable cross section figure. The area of cross section at A and B are 4 mm2 and 2mm2 respectively. If 1 cc of water enters per second through A, find (a) the speed of water at A, (b) the speed of water at B and (c) the pressure difference PA—PB.

Answer»

Water flows through a horizontal tube of variable cross section figure. The area of cross section at A and B are 4 $m m^{2}$ and 2 $m m^{2}$ respectively. If 1 cc of water enters per second through A, find (a) the speed of water at A, (b) the speed of water at B and (c) the pressure difference $P_{A} — P_{B}$ .

Discussion

35.	A block of mass 2 kg is attached to a spring of force constant k=10 N/m as shown in the figure. Find the range in which the block can be kept without slipping when the block is pulled or pushed towards the spring (spring is elongated or compressed). Take g=10 m/s2.
Answer» A block of mass $2 kg$ is attached to a spring of force constant $k = 10 N/m$ as shown in the figure. Find the range in which the block can be kept without slipping when the block is pulled or pushed towards the spring (spring is elongated or compressed). Take $g = 10 {m/s}^{2}$ .

Discussion

36.	In the arrangement shown in the figure a block of mass m=2 kg lies on a wedge of mass M=8 kg. The initial acceleration of the wedge (if the surfaces are smooth) given by 3√3gx ms−2, then x is.
Answer» In the arrangement shown in the figure a block of mass $m = 2 k g$ lies on a wedge of mass $M = 8 k g$ . The initial acceleration of the wedge (if the surfaces are smooth) given by $\frac{3 \sqrt{3} g}{x} m s^{- 2}$ , then $x$ is.

Discussion

37.	Photo cells are used for the
Answer» Photo cells are used for the

Discussion

38.	A string 25 cm long and having a mass of 2.5 gm is under tension. A pipe closed at one end is 40 cm long. When the string is set vibrating in its first overtone and the air in the pipe in its fundamental frequency, 8 beats per second are heard. It is observed that decreasing the tension in the string decreases beat frequency. If the speed of sound in air is 320 m/s, the tension in the string is N.
Answer» A string $25 cm$ long and having a mass of $2.5 gm$ is under tension. A pipe closed at one end is $40 cm$ long. When the string is set vibrating in its first overtone and the air in the pipe in its fundamental frequency, $8$ beats per second are heard. It is observed that decreasing the tension in the string decreases beat frequency. If the speed of sound in air is $320 m/s$ , the tension in the string is N.

Discussion

39.	A police car moving at 22 m/s, chases a motorcyclist. The police man sounds his horn at 176 Hz, while both of them move towards a stationary siren of frequency 165 Hz. The speed of the motorcyclist in m/s, if he does not observe any beats is (velocity of sound in air = 330 m/s)
Answer» A police car moving at 22 m/s, chases a motorcyclist. The police man sounds his horn at 176 Hz, while both of them move towards a stationary siren of frequency 165 Hz. The speed of the motorcyclist in $m / s$ , if he does not observe any beats is (velocity of sound in air = 330 m/s)

Discussion

40.	Two capacitors of capacitance 2C and C are charged to potential difference 2V and V respectively. Now the charged capacitors are connected with a resistor R as shown in figure. Switch ‘S’ is closed at t = 0. What is the total heat produced in circuit till steady state is obtained?
Answer» Two capacitors of capacitance 2C and C are charged to potential difference 2V and V respectively. Now the charged capacitors are connected with a resistor R as shown in figure. Switch ‘S’ is closed at t = 0. What is the total heat produced in circuit till steady state is obtained?

40.

Two capacitors of capacitance 2C and C are charged to potential difference 2V and V respectively. Now the charged capacitors are connected with a resistor R as shown in figure. Switch ‘S’ is closed at t = 0. What is the total heat produced in circuit till steady state is obtained?

Answer»

Two capacitors of capacitance 2C and C are charged to potential difference 2V and V respectively. Now the charged capacitors are connected with a resistor R as shown in figure. Switch ‘S’ is closed at t = 0.

What is the total heat produced in circuit till steady state is obtained?

Discussion

41.	A man, standing between two cliffs, claps his hands and starts hearing a series of echoes at intervals of one second. If the speed of sound in air is 340 ms−1, The distance between the cliffs is
Answer» A man, standing between two cliffs, claps his hands and starts hearing a series of echoes at intervals of one second. If the speed of sound in air is 340 $m s^{- 1}$ , The distance between the cliffs is

Discussion

42.

A loudspeaker diaphragm 0.2 m in diameter is vibrating at 1 kHz with an amplitude of 0.01×10−3 m. Assume that the air molecules in the viscinity have the same amplitude of vibration. Density of air is 1.29 kg/m3. Then match the items given in column I to that in column II. (Take velocity of sound = 340 m/s. ) Column I Column II i. Pressure amplitude immediately in front of the diaphragm is (in N/m2) a. 2.7×10−2 ii. Sound intensity in front of the diaphragm is (in W/m2 ) b. 2.15×10−5 iii. The acoustic power radiated is (in W) c. 27.55 iv. Intensity at 10 m from the loud speaker (in W/m2) d. 0.865

Answer»

A loudspeaker diaphragm 0.2 m in diameter is vibrating at 1 kHz with an amplitude of $0.01 \times 10^{- 3} m$ . Assume that the air molecules in the viscinity have the same amplitude of vibration. Density of air is $1.29 k g / m^{3}$ . Then match the items given in column I to that in column II. (Take velocity of sound = $340 m / s .$ )

Column I

Column II

i. Pressure amplitude immediately in front of the diaphragm is (in

N / m^{2}

)

a.

2.7 \times 10^{- 2}

ii. Sound intensity in front of the diaphragm is (in

W / m^{2}

)

b.

2.15 \times 10^{- 5}

iii. The acoustic power radiated is (in

W

)

c.

27.55

iv. Intensity at

10 m

from the loud speaker (in

W / m^{2}

)

d.

0.865

Discussion

43.	When a source of sound of frequency f crosses a stationary observer with a speed vs(<< speed of sound v), the apparent change in frequency Δf is given by
Answer» When a source of sound of frequency $f$ crosses a stationary observer with a speed $v_{s}$ ( $<<$ speed of sound $v$ ), the apparent change in frequency $Δ f$ is given by

Discussion

44.	The velocity v of a particle depends upon the time t according to the equation v=a+bt+cd+t.The dimensions of a, b, c and d are
Answer» The velocity v of a particle depends upon the time t according to the equation $v = a + b t + \frac{c}{d + t}$ .The dimensions of a, b, c and d are

Discussion

45.	If the 10 kg and 20 kg bodies are considered to be system 1 and 30 kg body is considered as system 2. The number of forces that would appear to be acting as an external force for system 1 is
Answer» If the $10 kg$ and $20 kg$ bodies are considered to be system $1$ and $30 kg$ body is considered as system $2$ . The number of forces that would appear to be acting as an external force for system 1 is

Discussion

46.	A uniform bar with mass m lies symmetrically across two rapidly rotating fixed rollers A and B, with distance ′l′ between the bar's centre of mass and each roller. The rollers whose direction of rotation are shown in figure slip against the bar with coefficient of friction μ. Suppose the bar is displaced horizontally by a small distance ′x′ and then released, find the time period of oscillation.
Answer» A uniform bar with mass $m$ lies symmetrically across two rapidly rotating fixed rollers A and B, with distance $^{'} l^{'}$ between the bar's centre of mass and each roller. The rollers whose direction of rotation are shown in figure slip against the bar with coefficient of friction $μ$ . Suppose the bar is displaced horizontally by a small distance $^{'} x^{'}$ and then released, find the time period of oscillation.

Discussion

47.	A body of mass 10 kg is lying on a rough plane inclined at an angle of 30∘ to the horizontal and the co-efficient of friction is 0.5. The minimum force required to pull the body up the plane is (g=9.8 m/s2)
Answer» A body of mass $10 kg$ is lying on a rough plane inclined at an angle of $30^{\circ}$ to the horizontal and the co-efficient of friction is $0.5$ . The minimum force required to pull the body up the plane is ( $g = 9.8 {m/s}^{2}$ )

Discussion

48.	Find the acceleration of block A and B? Take g=10 m/s2
Answer» Find the acceleration of block $A$ and $B$ ? Take $g = 10 m / s^{2}$

Discussion

49.	Find the reading of the spring balance if M is in equilibrium. Assume all surfaces to be smooth. Take g=10 m/s2
Answer» Find the reading of the spring balance if $M$ is in equilibrium. Assume all surfaces to be smooth. Take $g = 10 m / s^{2}$

Discussion

50.	Is the value of k=14πϵ experimentally found? Or is it derived? If it is derived, how?
Answer» Is the value of $k = \frac{1}{4 π ϵ}$ experimentally found? Or is it derived? If it is derived, how?

Discussion

Explore topic-wise InterviewSolutions in Current Affairs.

Three charges Q,+q and +q are placed at the vertices of a right angled isosceles triangle as shown in figure. The net electrostatic energy of the configuration is zero, if Q is equal to

A ball rolls off the top of a stairway horizontally with a velocity of 4.5 ms−1. Each step is 0.2 m high and 0.3 m wide. If g is 10 ms−2, then the ball will strike the nth step where n is equal to

Given that, force varies with position(x) as F=1+2x+3x2+4x3+5x4, when x changes from 0 to 5 m, then work done by the force is

What is avalanche effect

What is the difference between a charge and a free electron

A football is kicked with a velocity of 20 m/s at an angle of 45∘ with the horizontal. Find the time taken by the ball (in sec) to strike the ground. Give answer correct to 1 decimal place ___

Distance between a frog and an insect on a horizontal plane is 9 m. Frog can jump with a maximum speed of √10 m/s . Minimum number of jumps required by the frog to catch the insect is (Take g=10 m/s2)

The mass M shown in the figure oscillates in simple harmonic motion with amplitude A. The amplitude of the point P is

A simple pendulum has a time period exactly 2s when used in a laboratory at north pole. What will be the time period if the same pendulum is used in a laboratory at equator? Account for the earth's rotation only. Take g Gmr2 = 9.8 m/s2 and radius of earth = 6400 km.

A block of mass 20 kg is suspended through two light spring balances as shown in figure. Calculate the reading of spring balance (1) and (2) respectively.

A body is moving with a constant speed v in a circle of radius r. What is the angular acceleration?

A double convex thin lens made of glass (refractive index 1.5) has both radii of curvature of magnitude 20 cm. Incident light rays parallel to the axis of the lens will converge at distance L such that

If mean wavelength of light radiated by 100 W lamp is 5000 Å, then the number of photons radiated per second are

What is the maximum potential difference that can be detected by a potentiometer?

According to sign convention, which of the distances measured in the figure are considered to be negative?

Consider the situation of the previous problem.Suppose the block of mass m1 is pulled by a constant force F1 and the other block is pulled by a constant force F2.Find the maximum elongation that the spring will suffer.

A wire is bent in th eform of a regular hexagon and a total cahrge q is distributed uniformly on it. What is the electric field at the centre? you may answer this part without making any numerical calculations.

For the force-displacement graph for a particle is as shown below. If the particle has mass of 2 kg and has initial velocity of 2 m/s, calculate final kinetic energy of particle, when it displaces from x=1 m to x=5 m.

The angular velocity and the amplitude of a simple pendulum is ω and a respectively. At a displacement X from the mean position if its kinetic energy is T and potential energy is V, then the ratio of T to V is [CBSE PMT 1991]

Silicon doped with Arsenic is an example of:

The electric field intensity due to a sphere (solid or hollow) at an external point varies as-

A solid sphere of density ρ and radius R is floating in a liquid of density σ with half its volume submerged. When the sphere pressed down slightly and released, it executes simple harmonic motion of time period T. If viscous effect is ignored, then

Water flows through a frictionless duct with a cross-section varying as shown in fig. Pressure p at points along the axis is represented by

The ratio of the longest to the shortest wavelength in the Balmer series of Hydrogen spectrum is

If charge on left of the 5 μF capacitor in the circuit segment shown in the figure is - 18 μC. The charge on the right plate of 3μF capacitor is

The charge on 3μF capacitor shown in the figure is:

A car travels first half distance with uniform speed of 60 km/hr. What should be its uniform speed (in km/hr) for the second half of the distance so that its average speed over the entire journey becomes 90 km/hr.

Water flows through a horizontal tube of variable cross section figure. The area of cross section at A and B are 4 mm2 and 2mm2 respectively. If 1 cc of water enters per second through A, find (a) the speed of water at A, (b) the speed of water at B and (c) the pressure difference PA—PB.

A block of mass 2 kg is attached to a spring of force constant k=10 N/m as shown in the figure. Find the range in which the block can be kept without slipping when the block is pulled or pushed towards the spring (spring is elongated or compressed). Take g=10 m/s2.

In the arrangement shown in the figure a block of mass m=2 kg lies on a wedge of mass M=8 kg. The initial acceleration of the wedge (if the surfaces are smooth) given by 3√3gx ms−2, then x is.

Photo cells are used for the

A police car moving at 22 m/s, chases a motorcyclist. The police man sounds his horn at 176 Hz, while both of them move towards a stationary siren of frequency 165 Hz. The speed of the motorcyclist in m/s, if he does not observe any beats is (velocity of sound in air = 330 m/s)

Two capacitors of capacitance 2C and C are charged to potential difference 2V and V respectively. Now the charged capacitors are connected with a resistor R as shown in figure. Switch ‘S’ is closed at t = 0. What is the total heat produced in circuit till steady state is obtained?

A man, standing between two cliffs, claps his hands and starts hearing a series of echoes at intervals of one second. If the speed of sound in air is 340 ms−1, The distance between the cliffs is

When a source of sound of frequency f crosses a stationary observer with a speed vs(&lt;&lt; speed of sound v), the apparent change in frequency Δf is given by

The velocity v of a particle depends upon the time t according to the equation v=a+bt+cd+t.The dimensions of a, b, c and d are

If the 10 kg and 20 kg bodies are considered to be system 1 and 30 kg body is considered as system 2. The number of forces that would appear to be acting as an external force for system 1 is

A body of mass 10 kg is lying on a rough plane inclined at an angle of 30∘ to the horizontal and the co-efficient of friction is 0.5. The minimum force required to pull the body up the plane is (g=9.8 m/s2)

Find the acceleration of block A and B? Take g=10 m/s2

Find the reading of the spring balance if M is in equilibrium. Assume all surfaces to be smooth. Take g=10 m/s2

Is the value of k=14πϵ experimentally found? Or is it derived? If it is derived, how?

When a source of sound of frequency f crosses a stationary observer with a speed vs(<< speed of sound v), the apparent change in frequency Δf is given by