50278 + Interview Questions in Physics

1.	Why is heat capacity a path function and not a state function where as temperature is a state function.
Answer» Why is heat capacity a path function and not a state function where as temperature is a state function.

Discussion

2.	A man is walking due east at the speed of 3 km/h. Rain appears to fall down vertically at the rate of 3 km/h. The magnitude of actual velocity of the rain is
Answer» A man is walking due east at the speed of $3 km/h$ . Rain appears to fall down vertically at the rate of $3 km/h$ . The magnitude of actual velocity of the rain is

Discussion

3.	Rain, driven by the wind, falls on a railway compartment with a velocity of 20 m/s, at an angle of 30∘ to the vertical. The train moves, along the direction of wind flow, at a speed of 108 km/hr. Determine the apparent velocity of rain for a person sitting in the train.
Answer» Rain, driven by the wind, falls on a railway compartment with a velocity of $20 m / s$ , at an angle of $30^{\circ}$ to the vertical. The train moves, along the direction of wind flow, at a speed of $108 k m / h r$ . Determine the apparent velocity of rain for a person sitting in the train.

Discussion

4.	A glass prism of refractive index 1.5 is immersed in water [μ=43] as shown in figure. A light beam incident normally on the face AB is totally reflected to reach the face BC, if
Answer» A glass prism of refractive index $1.5$ is immersed in water $[μ = \frac{4}{3}]$ as shown in figure. A light beam incident normally on the face $A B$ is totally reflected to reach the face $B C$ , if

Discussion

5.	The central fringe of interference pattern produced by light of wavelength 6000 Å is found to shift to the position of 4th bright fringe, after a glass plate of μ=1.5 is introduced. The thickness of the glass plate is:
Answer» The central fringe of interference pattern produced by light of wavelength $6000 Å$ is found to shift to the position of $4^{th}$ bright fringe, after a glass plate of $μ = 1.5$ is introduced. The thickness of the glass plate is:

Discussion

6.	Find the mass (m) of the rocket as a function of time, if it moves with a constant acceleration a in the absence of external force. The gas escapes with a constant velocity u relative to the rocket and its initial mass was m0.
Answer» Find the mass $(m)$ of the rocket as a function of time, if it moves with a constant acceleration $a$ in the absence of external force. The gas escapes with a constant velocity $u$ relative to the rocket and its initial mass was $m_{0}$ .

Discussion

7.	Two equal forces act a point. The square of their resultant is three times their product of magnitudes. The angle between them is
Answer» Two equal forces act a point. The square of their resultant is three times their product of magnitudes. The angle between them is

Discussion

8.	A stone is projected from a horizontal plane. It attains maximum height H and strikes a stationary smooth wall and falls on the ground vertically below the maximum height. Assume the collision to be elastic. The height of the point on the wall where ball will strike is
Answer» A stone is projected from a horizontal plane. It attains maximum height H and strikes a stationary smooth wall and falls on the ground vertically below the maximum height. Assume the collision to be elastic. The height of the point on the wall where ball will strike is

8.

A stone is projected from a horizontal plane. It attains maximum height H and strikes a stationary smooth wall and falls on the ground vertically below the maximum height. Assume the collision to be elastic. The height of the point on the wall where ball will strike is

Answer»

A stone is projected from a horizontal plane. It attains maximum height H and strikes a stationary smooth wall and falls on the ground vertically below the maximum height. Assume the collision to be elastic. The height of the point on the wall where ball will strike is

Discussion

9.	Same force acts on two bodies of different masses 3kg and 5kg initially at rest. The ratio of time required to acquire same ﬁnal velocity is:
Answer» Same force acts on two bodies of different masses 3kg and 5kg initially at rest. The ratio of time required to acquire same ﬁnal velocity is:

Discussion

10.	The vector sum of the forces 10 N and 6 N can be
Answer» The vector sum of the forces $10 N$ and $6 N$ can be

Discussion

11.	The dimension of coefficient of thermal conductivity is (dQdt=−KAdTdx), where dQ is heat transferred, dt is time taken, K is coefficient of thermal conductivity, A is cross-sectional area of conductor, dT is change in temperature and dx is length of conductor.
Answer» The dimension of coefficient of thermal conductivity is $(\frac{d Q}{d t} = - K A \frac{d T}{d x})$ , where $d Q$ is heat transferred, $d t$ is time taken, $K$ is coefficient of thermal conductivity, $A$ is cross-sectional area of conductor, $d T$ is change in temperature and $d x$ is length of conductor.

Discussion

12.	A block, released from rest from the top of a smooth inclined plane of angle of inclination θ1, reaches the bottom in time t1. The same block, released from rest from the top of another smooth inclined plane of angle of inclination θ2, reaches the bottom in time t2. If the two inclined planes have the same height, the relation between t1 and t2 is
Answer» A block, released from rest from the top of a smooth inclined plane of angle of inclination $θ_{1}$ , reaches the bottom in time $t_{1}$ . The same block, released from rest from the top of another smooth inclined plane of angle of inclination $θ_{2}$ , reaches the bottom in time $t_{2}$ . If the two inclined planes have the same height, the relation between $t_{1}$ and $t_{2}$ is

Discussion

13.	A long cylindrical wire of radius a carries a current i distributed uniformly over its cross section. If the magnetic fields at distances r<a and R>a from the axis have equal magnitude, then:
Answer» A long cylindrical wire of radius $a$ carries a current $i$ distributed uniformly over its cross section. If the magnetic fields at distances $r < a$ and $R > a$ from the axis have equal magnitude, then:

Discussion

14.	Two thin hoops of masses m1 and m2 have radii r1 and r2. They are mounted rigidly on a frame of negligible mass as shown. The moment of inertia of the system about an axis passing through the centre and perpendicular (normal ) to the frame is
Answer» Two thin hoops of masses $m_{1}$ and $m_{2}$ have radii $r_{1}$ and $r_{2}$ . They are mounted rigidly on a frame of negligible mass as shown. The moment of inertia of the system about an axis passing through the centre and perpendicular (normal ) to the frame is

Discussion

15.	A body, acted upon by a force of 50 N is displaced through a distance 10 meter in a direction making an angle of 60∘ with the force. The work done by the force be
Answer» A body, acted upon by a force of 50 N is displaced through a distance 10 meter in a direction making an angle of $60^{\circ}$ with the force. The work done by the force be

Discussion

16.	A solenoid of length 50 cm with 600 turns is connected to a cell and current through the solenoid is 20πA. Find magnetic field inside the solenoid (in central region). Assume solenoid is ideal
Answer» A solenoid of length $50 c m$ with $600 t u r n s$ is connected to a cell and current through the solenoid is $\frac{20}{π} A$ . Find magnetic field inside the solenoid (in central region). Assume solenoid is ideal

Discussion

17.	In figure there is a frame consisting of two square loops having resistors and inductors as shown. This frame is placed in uniform but time varying magnetic field is such a way that one of the loop is placed in crossed magnetic field and other is placed in dot magnetic field. Both magnetic fields are perpendicular to the planes of loops. If the magnetic field is given by B=(20+10t) Wb/m2 in both regions [l = 20 cm, b = 10 cm and R=10Ω , L = 10 H). The current in the frame as a function of time will be
Answer» In figure there is a frame consisting of two square loops having resistors and inductors as shown. This frame is placed in uniform but time varying magnetic field is such a way that one of the loop is placed in crossed magnetic field and other is placed in dot magnetic field. Both magnetic fields are perpendicular to the planes of loops. If the magnetic field is given by $B = (20 + 10 t) W b / m^{2}$ in both regions [l = 20 cm, b = 10 cm and R=10 $Ω$ , L = 10 H). The current in the frame as a function of time will be

Discussion

18.	Two equal forces act at a point. The square of their resultant is three times their product of magnitudes. The angle between them is
Answer» Two equal forces act at a point. The square of their resultant is three times their product of magnitudes. The angle between them is

Discussion

19.	A particle is having potential energy 13 of the maximum value at a distance of 4 cm from mean position. Amplitude of motion is
Answer» A particle is having potential energy $\frac{1}{3}$ of the maximum value at a distance of 4 cm from mean position. Amplitude of motion is

Discussion

20.	In the given circuit, let i1 be the current drawn from battery at time t=0 i.e. when switch is just closed and i2 be steady state current at t=∞, then the ratio i1i2 is
Answer» In the given circuit, let $i_{1}$ be the current drawn from battery at time $t = 0$ i.e. when switch is just closed and $i_{2}$ be steady state current at $t = \infty$ , then the ratio $\frac{i_{1}}{i_{2}}$ is

Discussion

21.	Two steel balls of equal diameter are connected by a rigid bar of negligible weight as shown and are dropped in the horizontal position from height h above the heavy steel and brass base plates. If the coefficient of restitution between the ball and the steel base is 0.6 and that between the other ball and the brass base is 0.4, the angular velocity of the bar immediately after rebound is (Assume the two impacts are simultaneous and take g=10 m/s2).
Answer» Two steel balls of equal diameter are connected by a rigid bar of negligible weight as shown and are dropped in the horizontal position from height $h$ above the heavy steel and brass base plates. If the coefficient of restitution between the ball and the steel base is $0.6$ and that between the other ball and the brass base is $0.4$ , the angular velocity of the bar immediately after rebound is (Assume the two impacts are simultaneous and take $g = 10 {m/s}^{2}$ ).

Discussion

22.	A wire loop enclosing a semicircle of radius R is located on the boundary of a uniform magnetic field B . At the moment t=0 , the loop is set into rotation with constant angular acceleration α about an axis O . The clockwise emf direction is taken to be positive and the magnitude of variation of emf as a function of time is denoted by E . If t1 and t2 are the time required to complete first half and second half circle respectively then, which of of the following options are correct? (En is the inducede emf produced in nth half rotation.)
Answer» A wire loop enclosing a semicircle of radius $R$ is located on the boundary of a uniform magnetic field $B$ . At the moment $t = 0$ , the loop is set into rotation with constant angular acceleration α about an axis $O$ . The clockwise emf direction is taken to be positive and the magnitude of variation of emf as a function of time is denoted by E . If $t_{1}$ and $t_{2}$ are the time required to complete first half and second half circle respectively then, which of of the following options are correct? ( $E_{n}$ is the inducede emf produced in nth half rotation.)

Discussion

23.	A body of mass 18 kg initially at rest explodes into three fragments with masses in the ratio of 2:1:3. If smaller fragments fly in mutually perpendicular directions and their velocities are 10 m/s and 5 m/s respectively, then what is the speed of the heaviest fragment?
Answer» A body of mass $18 kg$ initially at rest explodes into three fragments with masses in the ratio of $2 : 1 : 3$ . If smaller fragments fly in mutually perpendicular directions and their velocities are $10 m/s$ and $5 m/s$ respectively, then what is the speed of the heaviest fragment?

Discussion

24.	A body of mass M is attached to the lower end of a metal wire, whose upper end is fixed. The elongation of this wire is l.
Answer» A body of mass M is attached to the lower end of a metal wire, whose upper end is fixed. The elongation of this wire is l.

Discussion

25.	The position of a particle along x-axis at time t is given by x=1+t−t2 m. The distance travelled by the particle in first 2 sec is
Answer» The position of a particle along x-axis at time $t$ is given by $x = 1 + t - t^{2} m$ . The distance travelled by the particle in first $2 sec$ is

Discussion

26.	A rocket is in gravity free space. A scientist wants the acceleration of the rocket to be 2 m/s2. Initial mass of the rocket is 1000 kg and the speed of ejection of burnt fuel w.r.t the rocket is 500 m/s. Find the rate of consumption of fuel (in kg/s), so that the rocket will have an acceleration of 2 m/s2.
Answer» A rocket is in gravity free space. A scientist wants the acceleration of the rocket to be $2 {m/s}^{2}$ . Initial mass of the rocket is $1000 kg$ and the speed of ejection of burnt fuel w.r.t the rocket is $500 m/s$ . Find the rate of consumption of fuel $(in kg/s)$ , so that the rocket will have an acceleration of $2 {m/s}^{2} .$

Discussion

27.	Find the projection of (→a+2→b) on →c where →a=2^i−2^j+^k,→b=^i+2^j−2^k and →c=2^i−^j+4^k
Answer» Find the projection of $(\to a + 2 \to b)$ on $\to c$ where $\to a = 2^i - 2^j +^k, \to b =^i + 2^j - 2^k$ and $\to c = 2^i -^j + 4^k$

Discussion

28.	The electric filed due to a uniformly charged spherical shell of charge 'Q' and radius 'R' at a distance 'r' is for r<R, and for r>R.
Answer» The electric filed due to a uniformly charged spherical shell of charge 'Q' and radius 'R' at a distance 'r' is for $r < R$ , and for $r > R$ .

Discussion

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

29.

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

Answer»

What is the angle between the following vectors?

$\to A =^i +^j +^k$ and $\to B = - 2^i - 2^j - 2^k$ .

Discussion

30.	The correct formula for specific gravity of a substance is
Answer» The correct formula for specific gravity of a substance is

Discussion

31.	If F=GmMr2, then dFdr=?
Answer» If $F = \frac{G m M}{r^{2}}$ , then $\frac{d F}{d r} = ?$

Discussion

32.	A ship of mass 3×107 kg initially at rest is pulled by a force of 5×104 N through a distance of 3 m. Assume that the resistance due to water is negligible. The speed of the ship is
Answer» A ship of mass $3 \times 10^{7} k g$ initially at rest is pulled by a force of $5 \times 10^{4} N$ through a distance of $3 m$ . Assume that the resistance due to water is negligible. The speed of the ship is

Discussion

33.	Volume of a cylinder increases by 6 % upon heating. The area of its curved surface will increase by
Answer» Volume of a cylinder increases by $6 %$ upon heating. The area of its curved surface will increase by

Discussion

34.	If the terminal speed of a sphere of gold (density =19.5 kg/m3) is 0.2 m/s in a viscous liquid (density =1.5 kg/m3), find the terminal speed of a sphere of silver (density =10.5 kg/m3) of the same size in the same liquid
Answer» If the terminal speed of a sphere of gold (density $= 19.5 {kg/m}^{3}$ ) is $0.2 m/s$ in a viscous liquid (density $= 1.5 {kg/m}^{3}$ ), find the terminal speed of a sphere of silver (density $= 10.5 {kg/m}^{3}$ ) of the same size in the same liquid

Discussion

35.	Two soap bubbles are blown. In first bubble, excess pressure is 4 times that of second bubble. The ratio of the radii of first and second soap bubble is
Answer» Two soap bubbles are blown. In first bubble, excess pressure is $4$ times that of second bubble. The ratio of the radii of first and second soap bubble is

Discussion

36.	The resultant of two forces 3P and 2P is R. If the first force is doubled then the resultant is also doubled. The angle between the two forces is
Answer» The resultant of two forces 3P and 2P is R. If the first force is doubled then the resultant is also doubled. The angle between the two forces is

Discussion

37.	A weight thermometer contains 51 gm of mercury at 0∘C. When placed in an oil bath 1.0 gm is found to overflow. Find the temperature of oil bath. Coefficient of cubical expansion of mercury and glass are 0.00018∘C and 0.000026∘C respectively.
Answer» A weight thermometer contains 51 gm of mercury at $0^{\circ} C$ . When placed in an oil bath 1.0 gm is found to overflow. Find the temperature of oil bath. Coefficient of cubical expansion of mercury and glass are ${0.00018}^{\circ} C$ and ${0.000026}^{\circ} C$ respectively.

Discussion

38.	A semicircular ring of mass m and a semicircular disc of mass 2m of same radius are joined together as shown. Find the distance of COM from their geometric centre.
Answer» A semicircular ring of mass $m$ and a semicircular disc of mass $2 m$ of same radius are joined together as shown. Find the distance of COM from their geometric centre.

Discussion

39.	Two balls A and B are thrown with speed u and u/2 respectively. Both the balls cover the same horizontal distance before returning to the horizontal plane of projection. If the angle of projection of ball of B is 15∘ with the horizontal, then the angle of projection of A is
Answer» Two balls $A$ and $B$ are thrown with speed $u$ and $u / 2$ respectively. Both the balls cover the same horizontal distance before returning to the horizontal plane of projection. If the angle of projection of ball of $B$ is $15^{\circ}$ with the horizontal, then the angle of projection of $A$ is

Discussion

40.	A cylinder is rotating with angular velocity ω and angular acceleration α at any instant, while translating with velocity V. Find the net acceleration of point P at this instant (radius of cylinder is R).
Answer» A cylinder is rotating with angular velocity ω and angular acceleration α at any instant, while translating with velocity V. Find the net acceleration of point P at this instant (radius of cylinder is R).

40.

A cylinder is rotating with angular velocity ω and angular acceleration α at any instant, while translating with velocity V. Find the net acceleration of point P at this instant (radius of cylinder is R).

Answer»

A cylinder is rotating with angular velocity ω and angular acceleration α at any instant, while translating with velocity V. Find the net acceleration of point P at this instant (radius of cylinder is R).

Discussion

41.	A iron rod of length 50 cm is joined at an end to an aluminum rod of length 100 cm. All measurements refer to 20∘C. The coefficients of linear expansion of iron and aluminum are 12×10−6/∘C and 24×10−6/∘C respectively. The average coefficient of composite system is
Answer» A iron rod of length 50 cm is joined at an end to an aluminum rod of length 100 cm. All measurements refer to $20^{\circ} C$ . The coefficients of linear expansion of iron and aluminum are $12 \times 10^{- 6} /^{\circ} C$ and $24 \times 10^{- 6} /^{\circ} C$ respectively. The average coefficient of composite system is

Discussion

42.	If force, F =x (volume)(speed)(energy)+ c , is a correct equation. Find the dimensions of x.
Answer» If force, F = $\frac{x (volume)}{(speed) (energy)}$ + c , is a correct equation. Find the dimensions of x.

Discussion

43.	If →a, →b, →c are mutually perpendicular vectors of equal magnitudes, then the angle between the vectors →a and →a+→b+→c is
Answer» If $\to a, \to b, \to c$ are mutually perpendicular vectors of equal magnitudes, then the angle between the vectors $\to a$ and $\to a + \to b + \to c$ is

Discussion

44.	A simple pendulum is suspended from the roof of a trolley which moves, in a horizontal direction with an acceleration a, and its time period is given by T=2π√lg′ which of the following correctly represent the value of g′.
Answer» A simple pendulum is suspended from the roof of a trolley which moves, in a horizontal direction with an acceleration $a$ , and its time period is given by $T = 2 π \sqrt{\frac{l}{g^{'}}}$ which of the following correctly represent the value of $g^{'}$ .

Discussion

45.	Question 26 Sudha finds out that the sharp image of the window pane of her science laboratory is formed at a distance of 15 cm from the lens. She now tries to focus the building visible to her outside the window instead of the window pane without disturbing the lens. In which direction will she move the screen to obtain a sharp image of the building? What is the approximate focal length of this lens?
Answer» Question 26 Sudha finds out that the sharp image of the window pane of her science laboratory is formed at a distance of 15 cm from the lens. She now tries to focus the building visible to her outside the window instead of the window pane without disturbing the lens. In which direction will she move the screen to obtain a sharp image of the building? What is the approximate focal length of this lens?

Discussion

46.	Point masses m1 and m2 are placed at the opposite ends of a rigid rod of length L of negligible mass. The rod is to be set rotating about an axis perpendicular to it. The position of point 'P' on this rod through which the axis should pass so that the work required to set the rod rotating with angular velocity ω0 is minimum is given by
Answer» Point masses $m_{1}$ and $m_{2}$ are placed at the opposite ends of a rigid rod of length $L$ of negligible mass. The rod is to be set rotating about an axis perpendicular to it. The position of point 'P' on this rod through which the axis should pass so that the work required to set the rod rotating with angular velocity $ω_{0}$ is minimum is given by

Discussion

47.	The first order reflections of a beam of X – rays of wavelength of 1.54˙A from the (100) face of a crystal of the simple cubic type occurs at an angle 11.29∘. Calculate the length of the unit cell.
Answer» The first order reflections of a beam of X – rays of wavelength of $1.54 ˙ A$ from the (100) face of a crystal of the simple cubic type occurs at an angle ${11.29}^{\circ}$ . Calculate the length of the unit cell.

Discussion

48.	A truck starts from rest with an acceleration of 1.5 m/s2 while a car 150 m behind starts from rest with an acceleration of 2 m/s2. What is the distance travelled by the car before it gets side by side to the truck?
Answer» A truck starts from rest with an acceleration of $1.5 {m/s}^{2}$ while a car $150 m$ behind starts from rest with an acceleration of $2 {m/s}^{2}$ . What is the distance travelled by the car before it gets side by side to the truck?

Discussion

49.	A point charge +Q is placed just outside an imaginary hemispherical surface of radius R as shown in the figure. Which of the following statements is/are correct?
Answer» A point charge $+ Q$ is placed just outside an imaginary hemispherical surface of radius $R$ as shown in the figure. Which of the following statements is/are correct?

Discussion

50.	Why does current in a steady state not flow in a capacitor connected across a battery but a momentary current does flow during charging or discharging of the capacitor?
Answer» Why does current in a steady state not flow in a capacitor connected across a battery but a momentary current does flow during charging or discharging of the capacitor?

Discussion

Explore topic-wise InterviewSolutions in Current Affairs.

Why is heat capacity a path function and not a state function where as temperature is a state function.

A man is walking due east at the speed of 3 km/h. Rain appears to fall down vertically at the rate of 3 km/h. The magnitude of actual velocity of the rain is

Rain, driven by the wind, falls on a railway compartment with a velocity of 20 m/s, at an angle of 30∘ to the vertical. The train moves, along the direction of wind flow, at a speed of 108 km/hr. Determine the apparent velocity of rain for a person sitting in the train.

A glass prism of refractive index 1.5 is immersed in water [μ=43] as shown in figure. A light beam incident normally on the face AB is totally reflected to reach the face BC, if

The central fringe of interference pattern produced by light of wavelength 6000 Å is found to shift to the position of 4th bright fringe, after a glass plate of μ=1.5 is introduced. The thickness of the glass plate is:

Find the mass (m) of the rocket as a function of time, if it moves with a constant acceleration a in the absence of external force. The gas escapes with a constant velocity u relative to the rocket and its initial mass was m0.

Two equal forces act a point. The square of their resultant is three times their product of magnitudes. The angle between them is

A stone is projected from a horizontal plane. It attains maximum height H and strikes a stationary smooth wall and falls on the ground vertically below the maximum height. Assume the collision to be elastic. The height of the point on the wall where ball will strike is

Same force acts on two bodies of different masses 3kg and 5kg initially at rest. The ratio of time required to acquire same ﬁnal velocity is:

The vector sum of the forces 10 N and 6 N can be

The dimension of coefficient of thermal conductivity is (dQdt=−KAdTdx), where dQ is heat transferred, dt is time taken, K is coefficient of thermal conductivity, A is cross-sectional area of conductor, dT is change in temperature and dx is length of conductor.

A long cylindrical wire of radius a carries a current i distributed uniformly over its cross section. If the magnetic fields at distances r&lt;a and R&gt;a from the axis have equal magnitude, then:

Two thin hoops of masses m1 and m2 have radii r1 and r2. They are mounted rigidly on a frame of negligible mass as shown. The moment of inertia of the system about an axis passing through the centre and perpendicular (normal ) to the frame is

A body, acted upon by a force of 50 N is displaced through a distance 10 meter in a direction making an angle of 60∘ with the force. The work done by the force be

A solenoid of length 50 cm with 600 turns is connected to a cell and current through the solenoid is 20πA. Find magnetic field inside the solenoid (in central region). Assume solenoid is ideal

Two equal forces act at a point. The square of their resultant is three times their product of magnitudes. The angle between them is

A particle is having potential energy 13 of the maximum value at a distance of 4 cm from mean position. Amplitude of motion is

In the given circuit, let i1 be the current drawn from battery at time t=0 i.e. when switch is just closed and i2 be steady state current at t=∞, then the ratio i1i2 is

A body of mass 18 kg initially at rest explodes into three fragments with masses in the ratio of 2:1:3. If smaller fragments fly in mutually perpendicular directions and their velocities are 10 m/s and 5 m/s respectively, then what is the speed of the heaviest fragment?

A body of mass M is attached to the lower end of a metal wire, whose upper end is fixed. The elongation of this wire is l.

The position of a particle along x-axis at time t is given by x=1+t−t2 m. The distance travelled by the particle in first 2 sec is

Find the projection of (→a+2→b) on →c where →a=2^i−2^j+^k,→b=^i+2^j−2^k and →c=2^i−^j+4^k

The electric filed due to a uniformly charged spherical shell of charge 'Q' and radius 'R' at a distance 'r' is for r&lt;R, and for r&gt;R.

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

The correct formula for specific gravity of a substance is

If F=GmMr2, then dFdr=?

A ship of mass 3×107 kg initially at rest is pulled by a force of 5×104 N through a distance of 3 m. Assume that the resistance due to water is negligible. The speed of the ship is

Volume of a cylinder increases by 6 % upon heating. The area of its curved surface will increase by

If the terminal speed of a sphere of gold (density =19.5 kg/m3) is 0.2 m/s in a viscous liquid (density =1.5 kg/m3), find the terminal speed of a sphere of silver (density =10.5 kg/m3) of the same size in the same liquid

Two soap bubbles are blown. In first bubble, excess pressure is 4 times that of second bubble. The ratio of the radii of first and second soap bubble is

The resultant of two forces 3P and 2P is R. If the first force is doubled then the resultant is also doubled. The angle between the two forces is

A weight thermometer contains 51 gm of mercury at 0∘C. When placed in an oil bath 1.0 gm is found to overflow. Find the temperature of oil bath. Coefficient of cubical expansion of mercury and glass are 0.00018∘C and 0.000026∘C respectively.

A semicircular ring of mass m and a semicircular disc of mass 2m of same radius are joined together as shown. Find the distance of COM from their geometric centre.

Two balls A and B are thrown with speed u and u/2 respectively. Both the balls cover the same horizontal distance before returning to the horizontal plane of projection. If the angle of projection of ball of B is 15∘ with the horizontal, then the angle of projection of A is

A cylinder is rotating with angular velocity ω and angular acceleration α at any instant, while translating with velocity V. Find the net acceleration of point P at this instant (radius of cylinder is R).

A iron rod of length 50 cm is joined at an end to an aluminum rod of length 100 cm. All measurements refer to 20∘C. The coefficients of linear expansion of iron and aluminum are 12×10−6/∘C and 24×10−6/∘C respectively. The average coefficient of composite system is

If force, F =x (volume)(speed)(energy)+ c , is a correct equation. Find the dimensions of x.

If →a, →b, →c are mutually perpendicular vectors of equal magnitudes, then the angle between the vectors →a and →a+→b+→c is

A simple pendulum is suspended from the roof of a trolley which moves, in a horizontal direction with an acceleration a, and its time period is given by T=2π√lg′ which of the following correctly represent the value of g′.

The first order reflections of a beam of X – rays of wavelength of 1.54˙A from the (100) face of a crystal of the simple cubic type occurs at an angle 11.29∘. Calculate the length of the unit cell.

A truck starts from rest with an acceleration of 1.5 m/s2 while a car 150 m behind starts from rest with an acceleration of 2 m/s2. What is the distance travelled by the car before it gets side by side to the truck?

A point charge +Q is placed just outside an imaginary hemispherical surface of radius R as shown in the figure. Which of the following statements is/are correct?

Why does current in a steady state not flow in a capacitor connected across a battery but a momentary current does flow during charging or discharging of the capacitor?

A long cylindrical wire of radius a carries a current i distributed uniformly over its cross section. If the magnetic fields at distances r<a and R>a from the axis have equal magnitude, then:

The electric filed due to a uniformly charged spherical shell of charge 'Q' and radius 'R' at a distance 'r' is for r<R, and for r>R.