50278 + Interview Questions in Physics

1.	A small sphere carrying a charge ‘q’ is hanging in between two parallel plates by a string of length L. Time period of pendulum is T0. When parallel plates are charged, the time period changes to T. The ratio TT0 is equal to
Answer» A small sphere carrying a charge ‘q’ is hanging in between two parallel plates by a string of length L. Time period of pendulum is $T_{0}$ . When parallel plates are charged, the time period changes to T. The ratio $\frac{T}{T_{0}}$ is equal to

Discussion

2.	The band gap between the valence and the conduction bands in zinc oxide (ZnO) is 3.2 eV. Suppose an electron in the conduction band combines with a hole in the valence band and the excess energy is released in the form of electromagnetic radiation. Find the maximum wavelength that can be emitted in this process.
Answer» The band gap between the valence and the conduction bands in zinc oxide (ZnO) is 3.2 eV. Suppose an electron in the conduction band combines with a hole in the valence band and the excess energy is released in the form of electromagnetic radiation. Find the maximum wavelength that can be emitted in this process.

Discussion

3.	The surface of water in a water tank on the top of a house is 4 m above the tap level. Find the pressure of water at the tap when the tap is closed. Is it necessary specify that the tap is closed? Take g =10 ms−2.
Answer» The surface of water in a water tank on the top of a house is 4 m above the tap level. Find the pressure of water at the tap when the tap is closed. Is it necessary specify that the tap is closed? Take g =10 $m s^{- 2}$ .

Discussion

4.	Two particles having masses m1 and m2 are situated in a plane perpendicular to line AB at a distance of r1 and r2 respectively as shown. Find the moment of inertia about axis passing through centre of mass and perpendicular to line joining m1 and m2.
Answer» Two particles having masses $m_{1}$ and $m_{2}$ are situated in a plane perpendicular to line AB at a distance of $r_{1}$ and $r_{2}$ respectively as shown. Find the moment of inertia about axis passing through centre of mass and perpendicular to line joining $m_{1}$ and $m_{2}$ .

4.

Two particles having masses m1 and m2 are situated in a plane perpendicular to line AB at a distance of r1 and r2 respectively as shown. Find the moment of inertia about axis passing through centre of mass and perpendicular to line joining m1 and m2.

Answer»

Two particles having masses $m_{1}$ and $m_{2}$ are situated in a plane perpendicular to line AB at a distance of $r_{1}$ and $r_{2}$ respectively as shown. Find the moment of inertia about axis passing through centre of mass and perpendicular to line joining $m_{1}$ and $m_{2}$ .

Discussion

5.	A Man has to go 50 M due month, 40 m due east and 20 M due south walk to reach a field. (a) what distance he has to walk to reach the field? (b) What is his displacement from his house to the field ?
Answer» A Man has to go 50 M due month, 40 m due east and 20 M due south walk to reach a field. (a) what distance he has to walk to reach the field? (b) What is his displacement from his house to the field ?

5.

A Man has to go 50 M due month, 40 m due east and 20 M due south walk to reach a field. (a) what distance he has to walk to reach the field? (b) What is his displacement from his house to the field ?

Answer»

A Man has to go 50 M due month, 40 m due east and 20 M due south walk to reach a field.

(a) what distance he has to walk to reach the field?

(b) What is his displacement from his house to the field ?

Discussion

6.	When NPN transistor is used as an amplifier :
Answer» When NPN transistor is used as an amplifier :

6.

When NPN transistor is used as an amplifier :

Answer»

When NPN transistor is used as an amplifier :

Discussion

7.	The relationship between Young's modulus Y, Bulk modulus K and modulus of rigidity η is
Answer» The relationship between Young's modulus Y, Bulk modulus K and modulus of rigidity $η$ is

Discussion

8.	One mole of an ideal gas undergoes a process pp01+(V/V0)2 where p0 and V0 are constants. Find the temperature of the gas when V=V0.
Answer» One mole of an ideal gas undergoes a process $p \frac{p_{0}}{1 + (V / V_{0})^{2}}$ where $p_{0}$ and $V_{0}$ are constants. Find the temperature of the gas when $V = V_{0}$ .

8.

One mole of an ideal gas undergoes a process pp01+(V/V0)2 where p0 and V0 are constants. Find the temperature of the gas when V=V0.

Answer»

One mole of an ideal gas undergoes a process

$p \frac{p_{0}}{1 + (V / V_{0})^{2}}$

where $p_{0}$ and $V_{0}$ are constants. Find the temperature of the gas when $V = V_{0}$ .

Discussion

9.	A glass contains some water at room temperature 200C. Refrigerated water is added to it slowly. When the temperature of the glass reaches 100 C, small droplets condense on the outer surface. Calculate the relative humidity in the room. The boiling point of water at a pressure of 17.5 mm of mercury is 200 C and at 8.9 mm of mercury it is 100 C.
Answer» A glass contains some water at room temperature $20^{0}$ C. Refrigerated water is added to it slowly. When the temperature of the glass reaches $10^{0}$ C, small droplets condense on the outer surface. Calculate the relative humidity in the room. The boiling point of water at a pressure of 17.5 mm of mercury is $20^{0}$ C and at 8.9 mm of mercury it is $10^{0}$ C.

Discussion

10.	The moment of inertia of a uniform circular disc of radius ′R′ and mass ′M′ about an axis passing from the edge of the disc and normal to the disc is
Answer» The moment of inertia of a uniform circular disc of radius $^{'} R^{'}$ and mass $^{'} M^{'}$ about an axis passing from the edge of the disc and normal to the disc is

Discussion

11.	In YDSE, the width of one slit is different from other, so that the amplitude of light from one slit is double that from the other. If Im is the maximum intensity, the intensity when they interfere with a phase difference of Φ is
Answer» In YDSE, the width of one slit is different from other, so that the amplitude of light from one slit is double that from the other. If $I_{m}$ is the maximum intensity, the intensity when they interfere with a phase difference of $Φ$ is

Discussion

12.	An arc lamp requires a direct current of 10 A at 80 V to function. If it is connected to a 220 V (rms), 50 Hz AC supply, the series inductor needed for it to work is close to
Answer» An arc lamp requires a direct current of $10 A$ at $80 V$ to function. If it is connected to a $220 V$ (rms), $50 Hz$ AC supply, the series inductor needed for it to work is close to

Discussion

13.	A particle of mass m is placed on top of a smooth hemispherical wedge of mass 4m at rest. The hemispherical wedge is kept on a frictionless horizontal surface. The particle is given a gentle push. The angular velocity of the particle relative to the wedge, if wedge has velocity v when particle has falls by an angle θ with respect to the wedge is
Answer» A particle of mass $m$ is placed on top of a smooth hemispherical wedge of mass $4 m$ at rest. The hemispherical wedge is kept on a frictionless horizontal surface. The particle is given a gentle push. The angular velocity of the particle relative to the wedge, if wedge has velocity $v$ when particle has falls by an angle $θ$ with respect to the wedge is

Discussion

14.	A liquid takes 5 minutes to cool from 800 C to 500 C . How much time will it take to cool from 600 C to 300 C ? The temperature of the surrounding is 200 C .
Answer» A liquid takes 5 minutes to cool from $80^{0} C t o 50^{0} C$ . How much time will it take to cool from $60^{0} C t o 30^{0} C$ ? The temperature of the surrounding is $20^{0}$ C .

Discussion

15.	The accompanying figure shows two concentric spherical shells isolated from each other. The smaller shell has radius b and net charge +Q. The larger shell has radius 2b and net charge –Q. If R is the distance from the common center, which is wrong
Answer» The accompanying figure shows two concentric spherical shells isolated from each other. The smaller shell has radius b and net charge +Q. The larger shell has radius 2b and net charge –Q. If R is the distance from the common center, which is wrong

15.

The accompanying figure shows two concentric spherical shells isolated from each other. The smaller shell has radius b and net charge +Q. The larger shell has radius 2b and net charge –Q. If R is the distance from the common center, which is wrong

Answer»

The accompanying figure shows two concentric spherical shells isolated from each other. The smaller shell has radius b and net charge +Q. The larger shell has radius 2b and net charge –Q. If R is the distance from the common center, which is wrong

Discussion

16.	An open organ pipe of length l is sounded together with another open organ pipe of length l + x in their fundamental tones. Speed of sound in air is v. The beat frequency heard will be (x ≪ l)
Answer» An open organ pipe of length l is sounded together with another open organ pipe of length l + x in their fundamental tones. Speed of sound in air is v. The beat frequency heard will be (x ≪ l)

Discussion

17.	Figure shows four situations in which a force acts on a box while the box slides rightward a distance d across a frictionless floor. The magnitude of the forces are identical with their orientations as shown. Identify under which condition the work done on the box during the displacement will be negative.
Answer» Figure shows four situations in which a force acts on a box while the box slides rightward a distance d across a frictionless floor. The magnitude of the forces are identical with their orientations as shown. Identify under which condition the work done on the box during the displacement will be negative.

Discussion

18.	A cabin rotates on a smooth horizontal table with a uniform angular velocity ω in a circular path of radius R (cabin is in a horizontal plane). A smooth path AB is made inside the cabin as shown in figure. If a particle is released from A to reach B along the path AB, then find the time taken by the particle to reach point B, considering length of path AB =L.
Answer» A cabin rotates on a smooth horizontal table with a uniform angular velocity $ω$ in a circular path of radius $R$ (cabin is in a horizontal plane). A smooth path $AB$ is made inside the cabin as shown in figure. If a particle is released from $A$ to reach $B$ along the path $AB$ , then find the time taken by the particle to reach point $B$ , considering length of path $AB$ $= L$ .

Discussion

19.	A force acts on a 30 g particle in such a way that the position of the particle as a function of time is given by x=3t−4t2+t3, where x is in meters and t is in seconds. The work done during the first 4 seconds is
Answer» A force acts on a $30 g$ particle in such a way that the position of the particle as a function of time is given by $x = 3 t - 4 t^{2} + t^{3}$ , where $x$ is in meters and $t$ is in seconds. The work done during the first $4$ seconds is

Discussion

20.	A car which has an initial velocity of 4 m/s accelerates at the rate of 2 m/s2 for 5 seconds. What will be the distance (in m) that it covers in these 5 seconds ?
Answer» A car which has an initial velocity of 4 m/s accelerates at the rate of $2 {m/s}^{2}$ for 5 seconds. What will be the distance (in $m$ ) that it covers in these 5 seconds ?

Discussion

21.	The upper half of an inclined plane of inclination θ is perfectly smooth while lower half is rough. A block starting from rest at the top of the plane will again come to rest at the bottom if the coefficient of friction between the block and lower half of plane is given by
Answer» The upper half of an inclined plane of inclination $θ$ is perfectly smooth while lower half is rough. A block starting from rest at the top of the plane will again come to rest at the bottom if the coefficient of friction between the block and lower half of plane is given by

Discussion

22.	A uniform rectangular lamina is shown in figure. Find the moment of inertia Icom about z axis which passes through its centre and perpendicular to its plane. Here b=10 m, l=20 m & M=12 kg.
Answer» A uniform rectangular lamina is shown in figure. Find the moment of inertia $I_{com}$ about $z$ axis which passes through its centre and perpendicular to its plane. Here $b = 10 m$ , $l = 20 m & M = 12 kg$ .

Discussion

23.	How to resolve velocity vector of a projectile motion into horizontal and vertical components?And how to find the time of flight using the components?
Answer» How to resolve velocity vector of a projectile motion into horizontal and vertical components?And how to find the time of flight using the components?

Discussion

24.	A disc is rolling (without slipping) on a horizontal surface. C is its centre and Q and P are two points equidistant from C. Let vP, vQ and vC be the magnitude of velocities of points P,Q and C respectively, then
Answer» A disc is rolling (without slipping) on a horizontal surface. C is its centre and Q and P are two points equidistant from C. Let $v_{P}, v_{Q} a n d v_{C}$ be the magnitude of velocities of points P,Q and C respectively, then

24.

A disc is rolling (without slipping) on a horizontal surface. C is its centre and Q and P are two points equidistant from C. Let vP, vQ and vC be the magnitude of velocities of points P,Q and C respectively, then

Answer»

A disc is rolling (without slipping) on a horizontal surface. C is its centre and Q and P are two points equidistant from C. Let $v_{P}, v_{Q} a n d v_{C}$ be the magnitude of velocities of points P,Q and C respectively, then

Discussion

25.	A block B of specific gravity 2 and another block C of specific gravity 0.5. Both are joined together and they are floating inside water such that they are completely dipped inside water, the ratio of the masses of the blocks B and C is
Answer» A block B of specific gravity 2 and another block C of specific gravity 0.5. Both are joined together and they are floating inside water such that they are completely dipped inside water, the ratio of the masses of the blocks B and C is

Discussion

26.	A 700 g solid cube having an edge of length 10 cm float in water. How much volume of the cube is outside the water? (Density of water = 1000 kg m−3)
Answer» A 700 g solid cube having an edge of length 10 cm float in water. How much volume of the cube is outside the water? (Density of water = 1000 kg $m^{- 3}$ )

Discussion

27.

What should be the length of aluminium and steel rod, so that steel rod is always 10 cm longer than aluminium, at all temperatures? αAl=12×10−5/oC αSteel=7×10−5/oC

Answer»

What should be the length of aluminium and steel rod, so that steel rod is always 10 cm longer than aluminium, at all temperatures?

α_{A l} = 12 \times 10 - 5 /^{o} C

α_{S t e e l} = 7 \times 10 - 5 /^{o} C

Discussion

28.	If XL>XC and R1=R2 then. Choose the correct alternative
Answer» If $X_{L} > X_{C}$ and $R_{1} = R_{2}$ then. Choose the correct alternative

28.

If XL>XC and R1=R2 then. Choose the correct alternative

Answer»

If $X_{L} > X_{C}$ and $R_{1} = R_{2}$ then. Choose the correct alternative

Discussion

29.	A solid ball of mass m is allowed to fall from a height h to a pan suspended with a spring of spring constant k. Assume the ball does not rebound and pan is massless, then amplitude of the oscillation is
Answer» A solid ball of mass $m$ is allowed to fall from a height $h$ to a pan suspended with a spring of spring constant $k$ . Assume the ball does not rebound and pan is massless, then amplitude of the oscillation is

Discussion

30.	Two identical rods are joined as shown. The system is pivoted at point O and is released from rest from the horizontal position. The speed of point A when OB become vertical is
Answer» Two identical rods are joined as shown. The system is pivoted at point $O$ and is released from rest from the horizontal position. The speed of point $A$ when $O B$ become vertical is

Discussion

31.	Figure shows the force versus displacement graph of the particle. Find out the work done by the force to displace the particle from x=0 to x=20 m.
Answer» Figure shows the force versus displacement graph of the particle. Find out the work done by the force to displace the particle from $x = 0$ to $x = 20 m$ .

Discussion

32.	Two ships are 80 km apart on North-South vertical at an instant as shown in the figure. The one farther North is streaming South at 40 km/hr and the other is streaming East at 30 km/hr. What is their distance of closest approach?
Answer» Two ships are $80 km$ apart on North-South vertical at an instant as shown in the figure. The one farther North is streaming South at $40 km/hr$ and the other is streaming East at $30 km/hr$ . What is their distance of closest approach?

Discussion

33.	A projectile has the same range R for two angles of projection. If T1 and T2 be the times of flight in the two cases, then R is
Answer» A projectile has the same range $R$ for two angles of projection. If $T_{1}$ and $T_{2}$ be the times of flight in the two cases, then $R$ is

Discussion

34.	A pendulum bob of mass m is suspended at rest. A constant horizontal force F=mg2 starts acting on it. The maximum angular deflection of the string is
Answer» A pendulum bob of mass m is suspended at rest. A constant horizontal force $F = \frac{m g}{2}$ starts acting on it. The maximum angular deflection of the string is

Discussion

35.	The e.m.f of the driver cell of a potentiometer is 2 V and its internal resistance is negligible. The length of the potentiometer wire is 100 cm and resistance is 5 Ω. How much resistance is to be connected in series with the potentiometer wire to have a potential gradient of 0.05 mVcm−1?
Answer» The e.m.f of the driver cell of a potentiometer is $2 V$ and its internal resistance is negligible. The length of the potentiometer wire is $100 c m$ and resistance is $5 Ω$ . How much resistance is to be connected in series with the potentiometer wire to have a potential gradient of $0.05 m V {c m}^{- 1}$ ?

Discussion

36.	A jar is filled with two non-mixing liquids 1 and 2 having densities s1 and s2 respectively. A solid ball, made of a material of density s3, is dropped in the jar. It comes to equilibrium in the position shown in the figure which of the following is true for s1, s2, s3?
Answer» A jar is filled with two non-mixing liquids 1 and 2 having densities s $_{1}$ and s $_{2}$ respectively. A solid ball, made of a material of density s $_{3}$ , is dropped in the jar. It comes to equilibrium in the position shown in the figure which of the following is true for s $_{1}$ , s $_{2}$ , s $_{3}$ ?

36.

A jar is filled with two non-mixing liquids 1 and 2 having densities s1 and s2 respectively. A solid ball, made of a material of density s3, is dropped in the jar. It comes to equilibrium in the position shown in the figure which of the following is true for s1, s2, s3?

Answer»

A jar is filled with two non-mixing liquids 1 and 2 having densities s $_{1}$ and s $_{2}$ respectively. A solid ball, made of a material of density s $_{3}$ , is dropped in the jar. It comes to equilibrium in the position shown in the figure which of the following is true for s $_{1}$ , s $_{2}$ , s $_{3}$ ?

Discussion

37.	The half-life of radioactive Radon is 3.8 days. The time at the end of which 116th of the Radon sample will remain undecayed is (given log10e=0.4343).
Answer» The half-life of radioactive Radon is 3.8 days. The time at the end of which $\frac{1}{16} t h$ of the Radon sample will remain undecayed is (given $l o g_{10} e = 0.4343$ ).

Discussion

38.	Einstein got Nobel prize on which of the following works
Answer» Einstein got Nobel prize on which of the following works

Discussion

39.	There are two identical holes on the opposite sides of a tank containing a liquid. The tank is open at the top. The difference in height between the two holes is 2h. As the liquid comes out of the two holes, the tank will experience a net horizontal force proportional to
Answer» There are two identical holes on the opposite sides of a tank containing a liquid. The tank is open at the top. The difference in height between the two holes is $2 h$ . As the liquid comes out of the two holes, the tank will experience a net horizontal force proportional to

Discussion

40.	A gas expands with temperature according to the relation V=kT2/3. What is the work done, when the temperature changes by 30∘C?
Answer» A gas expands with temperature according to the relation $V = k T^{2 / 3}$ . What is the work done, when the temperature changes by $30^{\circ} C$ ?

Discussion

41.	A block rests on a rough inclined plane making an angle of 30∘ with the horizontal. The coefficient of static friction between the block and the plane is 0.8. If the frictional force on the block is 10 N, the mass of the block (in kg) is (take g=10 m/s2)
Answer» A block rests on a rough inclined plane making an angle of $30^{\circ}$ with the horizontal. The coefficient of static friction between the block and the plane is $0.8$ . If the frictional force on the block is $10 N$ , the mass of the block (in $kg$ ) is (take $g = 10 {m/s}^{2}$ )

Discussion

42.	The weight of an aeroplane flying in the air is balanced by
Answer» The weight of an aeroplane flying in the air is balanced by

Discussion

43.	A force →F=^i−3^j−5^k acts at a point →r=4^i+8^j+a^k from the origin. What should be the value of 'a' so that the resulting torque will be maximum? What is the magnitude of the resulting maximum torque?
Answer» A force $\to F =^i - 3^j - 5^k$ acts at a point $\to r = 4^i + 8^j + a^k$ from the origin. What should be the value of ' $a$ ' so that the resulting torque will be maximum? What is the magnitude of the resulting maximum torque?

Discussion

44.	Why are pointed part not left on the surface of electric machines?
Answer» Why are pointed part not left on the surface of electric machines?

Discussion

45.	Figure shows a fixed wedge on which two blocks of masses 2 kg and 3 kg are placed on its smooth inclined surfaces. When the two blocks are released from rest, the acceleration of centre of mass of the two blocks is
Answer» Figure shows a fixed wedge on which two blocks of masses 2 kg and 3 kg are placed on its smooth inclined surfaces. When the two blocks are released from rest, the acceleration of centre of mass of the two blocks is

Discussion

46.	An aeroplane takes off at an angle of 30∘ to the horizontal. If the component of its velocity along the horizontal is 200√3km/h. What is its actual velocity? Also find the vertical component of velocity.
Answer» An aeroplane takes off at an angle of $30^{\circ}$ to the horizontal. If the component of its velocity along the horizontal is $200 \sqrt{3} k m / h$ . What is its actual velocity? Also find the vertical component of velocity.

Discussion

47.	12 mole of helium gas is contained in a container at S.T.P. The heat energy needed to double the pressure of the gas, keeping the volume constant (specific heat of the gas = 3 J gm−1 K−1) is
Answer» $\frac{1}{2}$ mole of helium gas is contained in a container at S.T.P. The heat energy needed to double the pressure of the gas, keeping the volume constant (specific heat of the gas = $3 J g m^{- 1} K^{- 1}$ ) is

47.

12 mole of helium gas is contained in a container at S.T.P. The heat energy needed to double the pressure of the gas, keeping the volume constant (specific heat of the gas = 3 J gm−1 K−1) is

Answer»

$\frac{1}{2}$ mole of helium gas is contained in a container at S.T.P. The heat energy needed to double the pressure of the gas, keeping the volume constant (specific heat of the gas = $3 J g m^{- 1} K^{- 1}$ ) is

Discussion

48.	A thin semicircular conducting ring of radius R is falling with its plane vertical, in a horizontal magnetic induction B. At the position MNQ, the speed of the ring is V and the potential difference developed across the ring is
Answer» A thin semicircular conducting ring of radius R is falling with its plane vertical, in a horizontal magnetic induction B. At the position MNQ, the speed of the ring is V and the potential difference developed across the ring is

48.

A thin semicircular conducting ring of radius R is falling with its plane vertical, in a horizontal magnetic induction B. At the position MNQ, the speed of the ring is V and the potential difference developed across the ring is

Answer»

A thin semicircular conducting ring of radius R is falling with its plane vertical, in a horizontal magnetic induction B. At the position MNQ, the speed of the ring is V and the potential difference developed across the ring is

Discussion

49.	A convex lens produces a real image m times the size of the object. What is the distance of the object from the lens?
Answer» A convex lens produces a real image m times the size of the object. What is the distance of the object from the lens?

Discussion

50.	Two bodies of masses m and M are placed at a distance d apart. The gravitational potential at the position where the gravitational field due to them is zero is V. Then what is V? Please explain in detail :)
Answer» Two bodies of masses m and M are placed at a distance d apart. The gravitational potential at the position where the gravitational field due to them is zero is V. Then what is V? Please explain in detail :)

Discussion

Explore topic-wise InterviewSolutions in Current Affairs.

A small sphere carrying a charge ‘q’ is hanging in between two parallel plates by a string of length L. Time period of pendulum is T0. When parallel plates are charged, the time period changes to T. The ratio TT0 is equal to

The surface of water in a water tank on the top of a house is 4 m above the tap level. Find the pressure of water at the tap when the tap is closed. Is it necessary specify that the tap is closed? Take g =10 ms−2.

Two particles having masses m1 and m2 are situated in a plane perpendicular to line AB at a distance of r1 and r2 respectively as shown. Find the moment of inertia about axis passing through centre of mass and perpendicular to line joining m1 and m2.

A Man has to go 50 M due month, 40 m due east and 20 M due south walk to reach a field. (a) what distance he has to walk to reach the field? (b) What is his displacement from his house to the field ?

When NPN transistor is used as an amplifier :

The relationship between Young's modulus Y, Bulk modulus K and modulus of rigidity η is

One mole of an ideal gas undergoes a process pp01+(V/V0)2 where p0 and V0 are constants. Find the temperature of the gas when V=V0.

The moment of inertia of a uniform circular disc of radius ′R′ and mass ′M′ about an axis passing from the edge of the disc and normal to the disc is

In YDSE, the width of one slit is different from other, so that the amplitude of light from one slit is double that from the other. If Im is the maximum intensity, the intensity when they interfere with a phase difference of Φ is

An arc lamp requires a direct current of 10 A at 80 V to function. If it is connected to a 220 V (rms), 50 Hz AC supply, the series inductor needed for it to work is close to

A liquid takes 5 minutes to cool from 800 C to 500 C . How much time will it take to cool from 600 C to 300 C ? The temperature of the surrounding is 200 C .

The accompanying figure shows two concentric spherical shells isolated from each other. The smaller shell has radius b and net charge +Q. The larger shell has radius 2b and net charge –Q. If R is the distance from the common center, which is wrong

An open organ pipe of length l is sounded together with another open organ pipe of length l + x in their fundamental tones. Speed of sound in air is v. The beat frequency heard will be (x ≪ l)

A force acts on a 30 g particle in such a way that the position of the particle as a function of time is given by x=3t−4t2+t3, where x is in meters and t is in seconds. The work done during the first 4 seconds is

A car which has an initial velocity of 4 m/s accelerates at the rate of 2 m/s2 for 5 seconds. What will be the distance (in m) that it covers in these 5 seconds ?

The upper half of an inclined plane of inclination θ is perfectly smooth while lower half is rough. A block starting from rest at the top of the plane will again come to rest at the bottom if the coefficient of friction between the block and lower half of plane is given by

A uniform rectangular lamina is shown in figure. Find the moment of inertia Icom about z axis which passes through its centre and perpendicular to its plane. Here b=10 m, l=20 m &amp; M=12 kg.

How to resolve velocity vector of a projectile motion into horizontal and vertical components?And how to find the time of flight using the components?

A disc is rolling (without slipping) on a horizontal surface. C is its centre and Q and P are two points equidistant from C. Let vP, vQ and vC be the magnitude of velocities of points P,Q and C respectively, then

A block B of specific gravity 2 and another block C of specific gravity 0.5. Both are joined together and they are floating inside water such that they are completely dipped inside water, the ratio of the masses of the blocks B and C is

A 700 g solid cube having an edge of length 10 cm float in water. How much volume of the cube is outside the water? (Density of water = 1000 kg m−3)

What should be the length of aluminium and steel rod, so that steel rod is always 10 cm longer than aluminium, at all temperatures? αAl=12×10−5/oC αSteel=7×10−5/oC

If XL&gt;XC and R1=R2 then. Choose the correct alternative

A solid ball of mass m is allowed to fall from a height h to a pan suspended with a spring of spring constant k. Assume the ball does not rebound and pan is massless, then amplitude of the oscillation is

Two identical rods are joined as shown. The system is pivoted at point O and is released from rest from the horizontal position. The speed of point A when OB become vertical is

Figure shows the force versus displacement graph of the particle. Find out the work done by the force to displace the particle from x=0 to x=20 m.

Two ships are 80 km apart on North-South vertical at an instant as shown in the figure. The one farther North is streaming South at 40 km/hr and the other is streaming East at 30 km/hr. What is their distance of closest approach?

A projectile has the same range R for two angles of projection. If T1 and T2 be the times of flight in the two cases, then R is

A pendulum bob of mass m is suspended at rest. A constant horizontal force F=mg2 starts acting on it. The maximum angular deflection of the string is

The e.m.f of the driver cell of a potentiometer is 2 V and its internal resistance is negligible. The length of the potentiometer wire is 100 cm and resistance is 5 Ω. How much resistance is to be connected in series with the potentiometer wire to have a potential gradient of 0.05 mVcm−1?

A jar is filled with two non-mixing liquids 1 and 2 having densities s1 and s2 respectively. A solid ball, made of a material of density s3, is dropped in the jar. It comes to equilibrium in the position shown in the figure which of the following is true for s1, s2, s3?

The half-life of radioactive Radon is 3.8 days. The time at the end of which 116th of the Radon sample will remain undecayed is (given log10e=0.4343).

Einstein got Nobel prize on which of the following works

There are two identical holes on the opposite sides of a tank containing a liquid. The tank is open at the top. The difference in height between the two holes is 2h. As the liquid comes out of the two holes, the tank will experience a net horizontal force proportional to

A gas expands with temperature according to the relation V=kT2/3. What is the work done, when the temperature changes by 30∘C?

A block rests on a rough inclined plane making an angle of 30∘ with the horizontal. The coefficient of static friction between the block and the plane is 0.8. If the frictional force on the block is 10 N, the mass of the block (in kg) is (take g=10 m/s2)

The weight of an aeroplane flying in the air is balanced by

A force →F=^i−3^j−5^k acts at a point →r=4^i+8^j+a^k from the origin. What should be the value of 'a' so that the resulting torque will be maximum? What is the magnitude of the resulting maximum torque?

Why are pointed part not left on the surface of electric machines?

Figure shows a fixed wedge on which two blocks of masses 2 kg and 3 kg are placed on its smooth inclined surfaces. When the two blocks are released from rest, the acceleration of centre of mass of the two blocks is

An aeroplane takes off at an angle of 30∘ to the horizontal. If the component of its velocity along the horizontal is 200√3km/h. What is its actual velocity? Also find the vertical component of velocity.

12 mole of helium gas is contained in a container at S.T.P. The heat energy needed to double the pressure of the gas, keeping the volume constant (specific heat of the gas = 3 J gm−1 K−1) is

A thin semicircular conducting ring of radius R is falling with its plane vertical, in a horizontal magnetic induction B. At the position MNQ, the speed of the ring is V and the potential difference developed across the ring is

A convex lens produces a real image m times the size of the object. What is the distance of the object from the lens?

Two bodies of masses m and M are placed at a distance d apart. The gravitational potential at the position where the gravitational field due to them is zero is V. Then what is V? ​​​​​​ Please explain in detail :)

A uniform rectangular lamina is shown in figure. Find the moment of inertia Icom about z axis which passes through its centre and perpendicular to its plane. Here b=10 m, l=20 m & M=12 kg.

If XL>XC and R1=R2 then. Choose the correct alternative

Two bodies of masses m and M are placed at a distance d apart. The gravitational potential at the position where the gravitational field due to them is zero is V. Then what is V? Please explain in detail :)