50278 + Interview Questions in Physics

1.	If a thermometer reads freezing point of water as 20∘C and boiling point as 150∘C, how much thermometer would read when the actual temperature is 60∘C?
Answer» If a thermometer reads freezing point of water as $20^{\circ} C$ and boiling point as $150^{\circ} C,$ how much thermometer would read when the actual temperature is $60^{\circ} C$ ?

Discussion

2.	If the distance between the earth and the sun were reduced to half its present value, Then the number of days in one year would have been
Answer» If the distance between the earth and the sun were reduced to half its present value, Then the number of days in one year would have been

Discussion

3.	The pressure exerted by 12 gm of an ideal gas at t∘C in a vessel of volume v litre is one atm. When the temperature is increased by 10∘C at the same volume, the pressure increases by 10%. Calculate the temperature t (in K) (Mol. Wt. of gas = 120)
Answer» The pressure exerted by $12 gm$ of an ideal gas at $t^{\circ} C$ in a vessel of volume v litre is one atm. When the temperature is increased by $10^{\circ} C$ at the same volume, the pressure increases by 10%. Calculate the temperature t (in K) (Mol. Wt. of gas = 120)

Discussion

4.	(a) Write the important properties of photons which are used to establish Einstein's photoelectric equation. (b) Use this equation to explain the concept of (i) threshold frequency and (ii) stopping potential.
Answer» (a) Write the important properties of photons which are used to establish Einstein's photoelectric equation. (b) Use this equation to explain the concept of (i) threshold frequency and (ii) stopping potential.

Discussion

5.	A body is traversing on the x-y plane with constant speed. At the start of the motion, the particles velocity is 40^i and after 30 sec its velocity becomes 40^j. Find the average acceleration.
Answer» A body is traversing on the x-y plane with constant speed. At the start of the motion, the particles velocity is $40^i$ and after 30 sec its velocity becomes $40^j$ . Find the average acceleration.

Discussion

6.	A particle executes simple harmonic motion (amplitude =A) between x=−A and x=+A. The time taken for it to go from 0 to A2 is T1 and to go from A2 to A is T2 . Then
Answer» A particle executes simple harmonic motion (amplitude $= A$ ) between $x = - A$ and $x = + A$ . The time taken for it to go from $0$ to $\frac{A}{2}$ is $T_{1}$ and to go from $\frac{A}{2}$ to $A$ is $T_{2}$ . Then

Discussion

7.	The benches of a gallery in a cricket stadium are 1 m wide and 1 m high. A batsman strikes the ball at a level one metre above the ground and hits a manmoth sixer. The ball starts at 35 m/s at an angle of 530 with the horizontal. The benches are perpendicular to the plane of motion and the first bench is 110 m from the batsman. On which bench will the ball hit ?
Answer» The benches of a gallery in a cricket stadium are 1 m wide and 1 m high. A batsman strikes the ball at a level one metre above the ground and hits a manmoth sixer. The ball starts at 35 m/s at an angle of $53^{0}$ with the horizontal. The benches are perpendicular to the plane of motion and the first bench is 110 m from the batsman. On which bench will the ball hit ?

Discussion

8.	According to the eqn. F=Eq, the force must be 0 if the charge is 0. Then, how will we find the force exerted by a charged comb on neutral pieces of paper?
Answer» According to the eqn. F=Eq, the force must be 0 if the charge is 0. Then, how will we find the force exerted by a charged comb on neutral pieces of paper?

Discussion

9.	In making an alloy , a substance of specific gravity s1 and mass m1 is mixed with another substance of specific gravity s2 and mass m2 ; then the specific gravity of the alloy is
Answer» In making an alloy , a substance of specific gravity $s_{1}$ and mass $m_{1}$ is mixed with another substance of specific gravity $s_{2}$ and mass $m_{2}$ ; then the specific gravity of the alloy is

Discussion

10.	A wave, y=2sin(πt+x+π6) is propagating on a stretched string fixed at one end. The equation of reflected wave can be given as
Answer» A wave, $y = 2 sin (π t + x + \frac{π}{6})$ is propagating on a stretched string fixed at one end. The equation of reflected wave can be given as

Discussion

11.	From a circle of radius (a)=3 cm, an isosceles right angled triangle with hypotenuse as the diameter of the circle is removed. The coordinates of the centre of mass of the remaining part from the centre of the circle is:
Answer» From a circle of radius $(a) = 3 cm$ , an isosceles right angled triangle with hypotenuse as the diameter of the circle is removed. The coordinates of the centre of mass of the remaining part from the centre of the circle is:

Discussion

12.	The displacement x of a particle along a straight line at time t is given by x=a0−a1t+a2t2. The acceleration of the particle is
Answer» The displacement $x$ of a particle along a straight line at time $t$ is given by $x = a_{0} - a_{1} t + a_{2} t^{2}$ . The acceleration of the particle is

Discussion

13.	The whistles of the two trains, A and B respectively, each have a frequency of 392 Hz. A is stationary and B is moving towards the right (away from A) at a speed of 35.0 m/s. A listener is between the two whistles and is moving towards the right with a speed of 15.0 m/s. No wind is blowing. How many number of beats are heard by the listener in 10 seconds ?
Answer» The whistles of the two trains, $A$ and $B$ respectively, each have a frequency of $392 Hz$ . $A$ is stationary and $B$ is moving towards the right (away from $A$ ) at a speed of $35.0 m/s$ . A listener is between the two whistles and is moving towards the right with a speed of $15.0 m/s$ . No wind is blowing. How many number of beats are heard by the listener in $10$ seconds ?

Discussion

14.	If gravitational field due to uniform thin hemispherical shell at point P is I, then the magnitude of gravitational field at Q is (Mass of hemisphere is M, radius R).
Answer» If gravitational field due to uniform thin hemispherical shell at point $P$ is $I$ , then the magnitude of gravitational field at $Q$ is (Mass of hemisphere is $M$ , radius $R$ ).

Discussion

15.	If the wavelength of an electomagnetic radiation is 2000∘A. What is the energy in ergs?
Answer» If the wavelength of an electomagnetic radiation is $2000^{\circ} A$ . What is the energy in ergs?

Discussion

16.	There exists a spherically symmetric gravitational system of particles of radius R. Its speed V as a function of distance r(0<r<∞) from the centre of the system is represented by
Answer» There exists a spherically symmetric gravitational system of particles of radius $R$ . Its speed $V$ as a function of distance $r (0 < r < \infty)$ from the centre of the system is represented by

Discussion

17.	A rough vertical board has an acceleration a so that a 2 kg block pressing against it does not fall. The coefficient of friction between the block and the board is μ. Then,
Answer» A rough vertical board has an acceleration $a$ so that a $2 k g$ block pressing against it does not fall. The coefficient of friction between the block and the board is $μ$ . Then,

Discussion

18.	The volume of one mole of an ideal gas with the abiabatic exponent γ is varied according to the law V = aT, where a is a gas constant. Find the amount of heat obtained by the gas in this process, if the gas temperature is increased by ΔT. R is a gas constant
Answer» The volume of one mole of an ideal gas with the abiabatic exponent $γ$ is varied according to the law $V = \frac{a}{T}$ , where $a$ is a gas constant. Find the amount of heat obtained by the gas in this process, if the gas temperature is increased by $Δ T$ . $R$ is a gas constant

Discussion

19.	In Newton's experiment of cooling, the water equivalent of two similar calorimeters is 10 gm each. They are filled with 350 gm of water and 300 gm of a liquid (equal volumes) separately. The time taken by water and liquid to cool from 70∘C to 60∘C is 3 min and 95 sec respectively. The specific heat of the liquid will be
Answer» In Newton's experiment of cooling, the water equivalent of two similar calorimeters is 10 gm each. They are filled with 350 gm of water and 300 gm of a liquid (equal volumes) separately. The time taken by water and liquid to cool from $70^{\circ} C$ to $60^{\circ} C$ is 3 min and 95 sec respectively. The specific heat of the liquid will be

Discussion

20.	A table with smooth horizontal surface is placed in a cabin which moves in a circle of a large radius R (figure 7-E5). A smooth pulley of small radius is fastened to the table. Two masses m and 2m placed on the table are connected through a string going over the pulley. Initially the masses are held by a person with the strings along the outwards radius and then the system is released from rest (with respect to the cabin). Find the magnitude of the initial acceleration of the masses as seen from the cabin and tension in the string.
Answer» A table with smooth horizontal surface is placed in a cabin which moves in a circle of a large radius R (figure 7-E5). A smooth pulley of small radius is fastened to the table. Two masses m and 2m placed on the table are connected through a string going over the pulley. Initially the masses are held by a person with the strings along the outwards radius and then the system is released from rest (with respect to the cabin). Find the magnitude of the initial acceleration of the masses as seen from the cabin and tension in the string.

20.

A table with smooth horizontal surface is placed in a cabin which moves in a circle of a large radius R (figure 7-E5). A smooth pulley of small radius is fastened to the table. Two masses m and 2m placed on the table are connected through a string going over the pulley. Initially the masses are held by a person with the strings along the outwards radius and then the system is released from rest (with respect to the cabin). Find the magnitude of the initial acceleration of the masses as seen from the cabin and tension in the string.

Answer»

A table with smooth horizontal surface is placed in a cabin which moves in a circle of a large radius R (figure 7-E5). A smooth pulley of small radius is fastened to the table. Two masses m and 2m placed on the table are connected through a string going over the pulley. Initially the masses are held by a person with the strings along the outwards radius and then the system is released from rest (with respect to the cabin). Find the magnitude of the initial acceleration of the masses as seen from the cabin and tension in the string.

Discussion

21.	Inner surface of a cylindrical shell of length l and of material of thermal conductivity k is kept at constant temperature T1 and outer surface of the cylinder is kept at constant temperature T2 such that (T1>T2) as shown in figure. Heat flows from inner surface to outer surface radially outward. Inner and outer radii of the shell are R and 2R respectively. Due to lack of space this cylinder has to be replaced by a smaller cylinder of length l2 inner and outer radii R4 and R respectively and thermal conductivity of material nk. If rate of radially outward heat flow remains same for same temperatures of inner and outer surface i.e., T1 and T2, then find the value of n.
Answer» Inner surface of a cylindrical shell of length $l$ and of material of thermal conductivity $k$ is kept at constant temperature $T_{1}$ and outer surface of the cylinder is kept at constant temperature $T_{2}$ such that $(T_{1} > T_{2})$ as shown in figure. Heat flows from inner surface to outer surface radially outward. Inner and outer radii of the shell are $R$ and $2 R$ respectively. Due to lack of space this cylinder has to be replaced by a smaller cylinder of length $\frac{l}{2}$ inner and outer radii $\frac{R}{4}$ and $R$ respectively and thermal conductivity of material $n k$ . If rate of radially outward heat flow remains same for same temperatures of inner and outer surface i.e., $T_{1}$ and $T_{2}$ , then find the value of $n$ .

Discussion

22.	As the temperature is raised from 20∘C to 40∘C, the average kinetic energy of neon atoms changes by a factor of which of the following?
Answer» As the temperature is raised from $20^{\circ}$ C to $40^{\circ} C$ , the average kinetic energy of neon atoms changes by a factor of which of the following?

Discussion

23.	Two satellites A and B go round a planet P in circular orbits having radil 4R and R respectively. If the speed of the satellite A is 3V, the speed of the satellite B will be
Answer» Two satellites A and B go round a planet P in circular orbits having radil 4R and R respectively. If the speed of the satellite A is 3V, the speed of the satellite B will be

Discussion

24.	A block of mass 1.2 kg moving at a speed of 20 cm/s collides head-on with a similar block kept at rest. The coefficient of restitution is 35. Find the loss of kinetic energy during the collision.
Answer» A block of mass 1.2 kg moving at a speed of 20 cm/s collides head-on with a similar block kept at rest. The coefficient of restitution is $\frac{3}{5}$ . Find the loss of kinetic energy during the collision.

Discussion

25.	A boy walks to his school at a distance of 6 km with constant speed of 2.5 km/hour and walks back with a constant speed of 4 km/hr. His average speed for round trip expressed in km/hr, is
Answer» A boy walks to his school at a distance of 6 km with constant speed of 2.5 km/hour and walks back with a constant speed of 4 km/hr. His average speed for round trip expressed in km/hr, is

Discussion

26.	A glass plate is partly dipped vertically in the mercury and the angle of contact is measured. If the plate is inclined, then the angle of contact will
Answer» A glass plate is partly dipped vertically in the mercury and the angle of contact is measured. If the plate is inclined, then the angle of contact will

Discussion

27.	Two infinitely large sheets having charge densities σ1 and σ1 respectively (σ1>σ2) are placed near each other separated by distance d. A charge q is placed in between two plates such that there is no effect on charge distribution on plates. Now this charge is moved at an angle of 45∘ with the horizontal, towards the plate having charge density σ2 by distance a(a<d). Find work done by electric field in the process.
Answer» Two infinitely large sheets having charge densities $σ_{1}$ and $σ_{1}$ respectively $(σ_{1} > σ_{2})$ are placed near each other separated by distance $d$ . A charge $q$ is placed in between two plates such that there is no effect on charge distribution on plates. Now this charge is moved at an angle of $45^{\circ}$ with the horizontal, towards the plate having charge density $σ_{2}$ by distance $a (a < d)$ . Find work done by electric field in the process.

Discussion

28.	A person with his hands in his pockets is skating on ice at the velocity of 10 m/s and describes a circle of radius 50 m. What is his inclination with vertical
Answer» A person with his hands in his pockets is skating on ice at the velocity of 10 m/s and describes a circle of radius 50 m. What is his inclination with vertical

Discussion

29.	Two identical particles having the same mass m and charges +q and −q, separated by a distance d, enter in a uniform magnetic field B directed perpendicular to paper inward with speeds v1 and v2 as shown in the figure. The particles will not collide if
Answer» Two identical particles having the same mass $m$ and charges $+ q$ and $- q$ , separated by a distance $d$ , enter in a uniform magnetic field $B$ directed perpendicular to paper inward with speeds $v_{1}$ and $v_{2}$ as shown in the figure. The particles will not collide if

Discussion

30.	A car is moving in a circular horizontal track of radius 10 m with a constant speed of 10 m/s. A bob is suspended from the roof of the car by a light wire of length 1 m. The angle made by the wire with the verticle is [Take g=10 m/s2]
Answer» A car is moving in a circular horizontal track of radius $10 m$ with a constant speed of $10 m/s$ . A bob is suspended from the roof of the car by a light wire of length $1 m$ . The angle made by the wire with the verticle is [Take $g = 10 {m/s}^{2}$ ]

Discussion

31.	A hollow sphere of mass M and radius R is rolling without slipping on a rough horizontal surface. Then the percentage of it's total KE which is translational, will be
Answer» A hollow sphere of mass $M$ and radius $R$ is rolling without slipping on a rough horizontal surface. Then the percentage of it's total $K E$ which is translational, will be

Discussion

32.	Vector A has a magnitude of 2 units and makes an angle of 30∘ with the positive x- axis, Vector B has a magnitude of 6 units and makes an angle of 30∘ with the y- axis(clockwise). Find the magnitude of the resultant of Vector A & -B and also the angle that it makes with Vector A.
Answer» Vector A has a magnitude of 2 units and makes an angle of $30^{\circ}$ with the positive x- axis, Vector B has a magnitude of 6 units and makes an angle of $30^{\circ}$ with the y- axis(clockwise). Find the magnitude of the resultant of Vector A & -B and also the angle that it makes with Vector A.

Discussion

33.	Water is filled in a rectangular tank of size 3m × 2 m × 1 m. (a) Find the total force exerted by the water on the bottom surface of the tank. (b) Consider a vertical side of area 2 m × 1 m. Take a horizontal strip of width δx metre in this side, situated at a depth of x metre from the surface of water. Find the force by the water on this strip. (c) Find the torque of the force calculated in part (b) about the bottom edge of this side. (d) Find the total force by the water on this side. (e) Find the total torque by the water on the side about the bottom edge. Neglect the atmospheric pressure and take g= 10ms−2.
Answer» Water is filled in a rectangular tank of size 3m $\times$ 2 m $\times$ 1 m. (a) Find the total force exerted by the water on the bottom surface of the tank. (b) Consider a vertical side of area 2 m $\times$ 1 m. Take a horizontal strip of width $δ$ x metre in this side, situated at a depth of x metre from the surface of water. Find the force by the water on this strip. (c) Find the torque of the force calculated in part (b) about the bottom edge of this side. (d) Find the total force by the water on this side. (e) Find the total torque by the water on the side about the bottom edge. Neglect the atmospheric pressure and take g= $10 m s^{- 2}$ .

33.

Water is filled in a rectangular tank of size 3m × 2 m × 1 m. (a) Find the total force exerted by the water on the bottom surface of the tank. (b) Consider a vertical side of area 2 m × 1 m. Take a horizontal strip of width δx metre in this side, situated at a depth of x metre from the surface of water. Find the force by the water on this strip. (c) Find the torque of the force calculated in part (b) about the bottom edge of this side. (d) Find the total force by the water on this side. (e) Find the total torque by the water on the side about the bottom edge. Neglect the atmospheric pressure and take g= 10ms−2.

Answer»

Water is filled in a rectangular tank of size 3m $\times$ 2 m $\times$ 1 m.

(a) Find the total force exerted by the water on the bottom surface of the tank.

(b) Consider a vertical side of area 2 m $\times$ 1 m. Take a horizontal strip of width $δ$ x metre in this side, situated at a depth of x metre from the surface of water. Find the force by the water on this strip.

(c) Find the torque of the force calculated in part (b) about the bottom edge of this side.

(d) Find the total force by the water on this side.

(e) Find the total torque by the water on the side about the bottom edge. Neglect the atmospheric pressure and take g= $10 m s^{- 2}$ .

Discussion

34.	A uniform slender bar AB of mass m and length L supported by a frictionless pivot at A is released from rest at its vertical position as shown in figure. Calculate the magnitude of the reaction at pivot when the bar just acquires the horizontal position shown dotted.
Answer» A uniform slender bar AB of mass m and length L supported by a frictionless pivot at A is released from rest at its vertical position as shown in figure. Calculate the magnitude of the reaction at pivot when the bar just acquires the horizontal position shown dotted.

34.

A uniform slender bar AB of mass m and length L supported by a frictionless pivot at A is released from rest at its vertical position as shown in figure. Calculate the magnitude of the reaction at pivot when the bar just acquires the horizontal position shown dotted.

Answer»

A uniform slender bar AB of mass m and length L supported by a frictionless pivot at A is released from rest at its vertical position as shown in figure. Calculate the magnitude of the reaction at pivot when the bar just acquires the horizontal position shown dotted.

Discussion

35.	Photon of 5.5 eV energy fall on the surface of the metal emitting photoelectrons of maximum kinetic energy 4.0 eV. The stopping voltage required for these electrons are
Answer» Photon of 5.5 eV energy fall on the surface of the metal emitting photoelectrons of maximum kinetic energy 4.0 eV. The stopping voltage required for these electrons are

Discussion

36.	A horizontal F is applied on a spherical shell of radius R at distance R/2 above center as shown in figure. Shell is doing pure rolling motion and friction acting on it is f=xFy then, y-x is
Answer» A horizontal F is applied on a spherical shell of radius R at distance R/2 above center as shown in figure. Shell is doing pure rolling motion and friction acting on it is $f = \frac{x F}{y}$ then, y-x is

Discussion

37.	Force F on a particle moving in a straight line varies with displacement d as shown in the figure. The work done on the particle during its displacement of 12 m is:
Answer» Force F on a particle moving in a straight line varies with displacement d as shown in the figure. The work done on the particle during its displacement of 12 m is:

37.

Force F on a particle moving in a straight line varies with displacement d as shown in the figure. The work done on the particle during its displacement of 12 m is:

Answer»

Force F on a particle moving in a straight line varies with displacement d as shown in the figure. The work done on the particle during its displacement of 12 m is:

Discussion

38.	The face BC of a prism of refractive index μ=√2 is silvered. Angle ∠BCA=30∘. A light ray incident on the face AC retraces the path. The value of incident angle θ is
Answer» The face BC of a prism of refractive index $μ = \sqrt{2}$ is silvered. Angle $∠ B C A = 30^{\circ}$ . A light ray incident on the face AC retraces the path. The value of incident angle $θ$ is

Discussion

39.	In Young's double slit experiment the separation d between the slits is 2 mm. The wavelength λ of the light used is 5896 Å and distance D between the screen and slits is 100 cm. It is found that the angular width of the fringes is 0.20°. To increase the fringe angular width to 0.21° (with same λ and D) the separation between the slits needs to be changed to
Answer» In Young's double slit experiment the separation $d$ between the slits is $2 m m$ . The wavelength $λ$ of the light used is $5896 Å$ and distance $D$ between the screen and slits is $100 c m$ . It is found that the angular width of the fringes is $0.20 °$ . To increase the fringe angular width to $0.21 °$ (with same $λ$ and $D$ ) the separation between the slits needs to be changed to

Discussion

40.	Two small particles A & B of masses M and 2M respectively are joined rigidly to the ends of a light rod of length l as shown in the figure. The system translates on a smooth horizontal surface with a velocity u in a direction perpendicular to the rod. A particle P of mass M kept at rest on the surface sticks to the particle ‘A’ after collision with it. Then choose the correct option(s):
Answer» Two small particles A & B of masses M and 2M respectively are joined rigidly to the ends of a light rod of length l as shown in the figure. The system translates on a smooth horizontal surface with a velocity u in a direction perpendicular to the rod. A particle P of mass M kept at rest on the surface sticks to the particle ‘A’ after collision with it. Then choose the correct option(s):

Discussion

41.	A photon of energy E ejects a photoelectron from a metal surface whose work function is W0. If this electron enters into a uniform magnetic field of induction B in a direction perpendicular to the field and describes a circular path of radius r, then the radius r is given by: (in the usual notation)
Answer» A photon of energy $E$ ejects a photoelectron from a metal surface whose work function is $W_{0}$ . If this electron enters into a uniform magnetic field of induction $B$ in a direction perpendicular to the field and describes a circular path of radius $r$ , then the radius $r$ is given by: (in the usual notation)

Discussion

42.	A particle of mass 4 kg moves in simple harmonic motion and its potential energy U varies with position x as shown in the figure. The time period of oscillation of the particle is 2πα second. Find the value of α.___
Answer» A particle of mass 4 kg moves in simple harmonic motion and its potential energy U varies with position x as shown in the figure. The time period of oscillation of the particle is $\frac{2 π}{α}$ second. Find the value of $α$ .___

Discussion

43.	If the length of the rod A is (3.25±0.01) cm and that of the rod B is (4.19±0.01) cm then the rod B is longer than rod A by
Answer» If the length of the rod $A$ is $(3.25 \pm 0.01) cm$ and that of the rod $B$ is $(4.19 \pm 0.01) cm$ then the rod $B$ is longer than rod $A$ by

Discussion

44.	A capacitor made of two parallel circular plates of area A holds a charge Q0 initially. Suppose that it discharges as Q(t)=Q0e−λt. During the discharge, the ratio ϵBϵE of the magnetic field energy ϵB to the electric field energy ϵE between the two plates is given by
Answer» A capacitor made of two parallel circular plates of area A holds a charge $Q_{0}$ initially. Suppose that it discharges as $Q (t) = Q_{0} e^{- λ t}$ . During the discharge, the ratio $\frac{ϵ_{B}}{ϵ_{E}}$ of the magnetic field energy $ϵ_{B}$ to the electric field energy $ϵ_{E}$ between the two plates is given by

Discussion

45.	A dipole consists of a light rod of length l, having two point charges +q and -q and of same mass m, joined at ends A and B of the rod. A uniform electric field E is present in the region and perpendicular to the length of the rod. The rod is released from rest from this position. The angular velocity of the rod, when it becomes parallel to the electric field for the first time is
Answer» A dipole consists of a light rod of length l, having two point charges +q and -q and of same mass m, joined at ends A and B of the rod. A uniform electric field E is present in the region and perpendicular to the length of the rod. The rod is released from rest from this position. The angular velocity of the rod, when it becomes parallel to the electric field for the first time is

Discussion

46.	The width of a door is 40 cm. If it is released by exerting a force of 2 N perpendicularly at its edge (away from the hinges). Compute the magnitude of torque produced which causes the door to open.
Answer» The width of a door is $40 cm$ . If it is released by exerting a force of $2 N$ perpendicularly at its edge (away from the hinges). Compute the magnitude of torque produced which causes the door to open.

Discussion

47.	One end of a uniform wire of length L and of weight W is attached rigidly to a point in the roof and a weight W1 is suspended from its lower end. If S is the area of cross section of the wire, the stress in the wire at a height 3L/4 from its lower end is
Answer» One end of a uniform wire of length $L$ and of weight $W$ is attached rigidly to a point in the roof and a weight $W_{1}$ is suspended from its lower end. If $S$ is the area of cross section of the wire, the stress in the wire at a height $3 L / 4$ from its lower end is

Discussion

48.	For a given velocity of projection from a point on the inclined plane, the maximum range down the plane is three times the maximum range up the incline. Then, the angle of inclination of the inclined plane is
Answer» For a given velocity of projection from a point on the inclined plane, the maximum range down the plane is three times the maximum range up the incline. Then, the angle of inclination of the inclined plane is

Discussion

49.	Acceleration of the particle in a rectilinear motion is given as a=4t+3 in (m/s2). The final position of the particle as a function of time t is (Given, at t=0,u=3 m/s,x=2 m)
Answer» Acceleration of the particle in a rectilinear motion is given as $a = 4 t + 3$ in $(m / s^{2})$ . The final position of the particle as a function of time $t$ is (Given, at $t = 0, u = 3 m / s, x = 2 m$ )

Discussion

50.	A block of mass m is placed on a smooth wedge of inclination θ. The whole system is accelerated horizontally so that the block does not slip on the wedge. The force exerted by the wedge on the block (g is the acceleration due to gravity) will be
Answer» A block of mass $m$ is placed on a smooth wedge of inclination $θ$ . The whole system is accelerated horizontally so that the block does not slip on the wedge. The force exerted by the wedge on the block ( $g$ is the acceleration due to gravity) will be

Discussion

Explore topic-wise InterviewSolutions in Current Affairs.

If a thermometer reads freezing point of water as 20∘C and boiling point as 150∘C, how much thermometer would read when the actual temperature is 60∘C?

If the distance between the earth and the sun were reduced to half its present value, Then the number of days in one year would have been

The pressure exerted by 12 gm of an ideal gas at t∘C in a vessel of volume v litre is one atm. When the temperature is increased by 10∘C at the same volume, the pressure increases by 10%. Calculate the temperature t (in K) (Mol. Wt. of gas = 120)

(a) Write the important properties of photons which are used to establish Einstein's photoelectric equation. (b) Use this equation to explain the concept of (i) threshold frequency and (ii) stopping potential.

A body is traversing on the x-y plane with constant speed. At the start of the motion, the particles velocity is 40^i and after 30 sec its velocity becomes 40^j. Find the average acceleration.

A particle executes simple harmonic motion (amplitude =A) between x=−A and x=+A. The time taken for it to go from 0 to A2 is T1 and to go from A2 to A is T2 . Then

According to the eqn. F=Eq, the force must be 0 if the charge is 0. Then, how will we find the force exerted by a charged comb on neutral pieces of paper?

In making an alloy , a substance of specific gravity s1 and mass m1 is mixed with another substance of specific gravity s2 and mass m2 ; then the specific gravity of the alloy is

A wave, y=2sin(πt+x+π6) is propagating on a stretched string fixed at one end. The equation of reflected wave can be given as

From a circle of radius (a)=3 cm, an isosceles right angled triangle with hypotenuse as the diameter of the circle is removed. The coordinates of the centre of mass of the remaining part from the centre of the circle is:

The displacement x of a particle along a straight line at time t is given by x=a0−a1t+a2t2. The acceleration of the particle is

If gravitational field due to uniform thin hemispherical shell at point P is I, then the magnitude of gravitational field at Q is (Mass of hemisphere is M, radius R).

If the wavelength of an electomagnetic radiation is 2000∘A. What is the energy in ergs?

There exists a spherically symmetric gravitational system of particles of radius R. Its speed V as a function of distance r(0&lt;r&lt;∞) from the centre of the system is represented by

A rough vertical board has an acceleration a so that a 2 kg block pressing against it does not fall. The coefficient of friction between the block and the board is μ. Then,

The volume of one mole of an ideal gas with the abiabatic exponent γ is varied according to the law V = aT, where a is a gas constant. Find the amount of heat obtained by the gas in this process, if the gas temperature is increased by ΔT. R is a gas constant

As the temperature is raised from 20∘C to 40∘C, the average kinetic energy of neon atoms changes by a factor of which of the following?

Two satellites A and B go round a planet P in circular orbits having radil 4R and R respectively. If the speed of the satellite A is 3V, the speed of the satellite B will be

A block of mass 1.2 kg moving at a speed of 20 cm/s collides head-on with a similar block kept at rest. The coefficient of restitution is 35. Find the loss of kinetic energy during the collision.

A boy walks to his school at a distance of 6 km with constant speed of 2.5 km/hour and walks back with a constant speed of 4 km/hr. His average speed for round trip expressed in km/hr, is

A glass plate is partly dipped vertically in the mercury and the angle of contact is measured. If the plate is inclined, then the angle of contact will

A person with his hands in his pockets is skating on ice at the velocity of 10 m/s and describes a circle of radius 50 m. What is his inclination with vertical

Two identical particles having the same mass m and charges +q and −q, separated by a distance d, enter in a uniform magnetic field B directed perpendicular to paper inward with speeds v1 and v2 as shown in the figure. The particles will not collide if

A car is moving in a circular horizontal track of radius 10 m with a constant speed of 10 m/s. A bob is suspended from the roof of the car by a light wire of length 1 m. The angle made by the wire with the verticle is [Take g=10 m/s2]

A hollow sphere of mass M and radius R is rolling without slipping on a rough horizontal surface. Then the percentage of it's total KE which is translational, will be

Vector A has a magnitude of 2 units and makes an angle of 30∘ with the positive x- axis, Vector B has a magnitude of 6 units and makes an angle of 30∘ with the y- axis(clockwise). Find the magnitude of the resultant of Vector A &amp; -B and also the angle that it makes with Vector A.

A uniform slender bar AB of mass m and length L supported by a frictionless pivot at A is released from rest at its vertical position as shown in figure. Calculate the magnitude of the reaction at pivot when the bar just acquires the horizontal position shown dotted.

Photon of 5.5 eV energy fall on the surface of the metal emitting photoelectrons of maximum kinetic energy 4.0 eV. The stopping voltage required for these electrons are

A horizontal F is applied on a spherical shell of radius R at distance R/2 above center as shown in figure. Shell is doing pure rolling motion and friction acting on it is f=xFy then, y-x is

Force F on a particle moving in a straight line varies with displacement d as shown in the figure. The work done on the particle during its displacement of 12 m is:

The face BC of a prism of refractive index μ=√2 is silvered. Angle ∠BCA=30∘. A light ray incident on the face AC retraces the path. The value of incident angle θ is

A particle of mass 4 kg moves in simple harmonic motion and its potential energy U varies with position x as shown in the figure. The time period of oscillation of the particle is 2πα second. Find the value of α.___

If the length of the rod A is (3.25±0.01) cm and that of the rod B is (4.19±0.01) cm then the rod B is longer than rod A by

A capacitor made of two parallel circular plates of area A holds a charge Q0 initially. Suppose that it discharges as Q(t)=Q0e−λt. During the discharge, the ratio ϵBϵE of the magnetic field energy ϵB to the electric field energy ϵE between the two plates is given by

The width of a door is 40 cm. If it is released by exerting a force of 2 N perpendicularly at its edge (away from the hinges). Compute the magnitude of torque produced which causes the door to open.

One end of a uniform wire of length L and of weight W is attached rigidly to a point in the roof and a weight W1 is suspended from its lower end. If S is the area of cross section of the wire, the stress in the wire at a height 3L/4 from its lower end is

For a given velocity of projection from a point on the inclined plane, the maximum range down the plane is three times the maximum range up the incline. Then, the angle of inclination of the inclined plane is

Acceleration of the particle in a rectilinear motion is given as a=4t+3 in (m/s2). The final position of the particle as a function of time t is (Given, at t=0,u=3 m/s,x=2 m)

A block of mass m is placed on a smooth wedge of inclination θ. The whole system is accelerated horizontally so that the block does not slip on the wedge. The force exerted by the wedge on the block (g is the acceleration due to gravity) will be

There exists a spherically symmetric gravitational system of particles of radius R. Its speed V as a function of distance r(0<r<∞) from the centre of the system is represented by

Vector A has a magnitude of 2 units and makes an angle of 30∘ with the positive x- axis, Vector B has a magnitude of 6 units and makes an angle of 30∘ with the y- axis(clockwise). Find the magnitude of the resultant of Vector A & -B and also the angle that it makes with Vector A.