50278 + Interview Questions in Physics

1.	During oscillation velocity of particle is maximum at mean position .How ?
Answer» During oscillation velocity of particle is maximum at mean position . How ?

Discussion

2.	A p n photo diode is made of a material with a band gap of 2.0 e v . the minimum frequency of the radiation that can be absorbed by the material is nearly
Answer» A p n photo diode is made of a material with a band gap of 2.0 e v . the minimum frequency of the radiation that can be absorbed by the material is nearly

Discussion

3.	A cylinderswith a movable piston contains 3 moles of hydrogen at standard temperature andpressure. The walls of the cylinder are made of heat insulator, and the pistonis insulated by having a pile of sand on it/ By what factor does the pressureof the gas increase, if the gas is compressed to half it original volume?
Answer» A cylinders with a movable piston contains 3 moles of hydrogen at standard temperature and pressure. The walls of the cylinder are made of heat insulator, and the piston is insulated by having a pile of sand on it/ By what factor does the pressure of the gas increase, if the gas is compressed to half it original volume?

Discussion

4.	A particle returns to the starting point after 10 s if the rate of change of velocity during the motion is constant, then its location after 7 s will be same as that after
Answer» A particle returns to the starting point after $10 s$ if the rate of change of velocity during the motion is constant, then its location after $7 s$ will be same as that after

Discussion

5.	The horn of a car emits sound with a dominant frequency of 2400 Hz. What will be the apparent dominant frequency heard by a person standing on the road in front of the car if the car is approaching at 18.0 km/h ? Speed of sound in air = 340 m/s.
Answer» The horn of a car emits sound with a dominant frequency of 2400 Hz. What will be the apparent dominant frequency heard by a person standing on the road in front of the car if the car is approaching at 18.0 km/h ? Speed of sound in air = 340 m/s.

Discussion

6.	A person looking at a person wearing a shirt with a patterncomprising vertical and horizontal lines is able to see the verticallines more distinctly than the horizontal ones. What is this defect due to? How is such a defect of vision corrected?
Answer» A person looking at a person wearing a shirt with a patterncomprising vertical and horizontal lines is able to see the verticallines more distinctly than the horizontal ones. What is this defect due to? How is such a defect of vision corrected?

Discussion

7.	31. A block of mass 1 kg lies on a horizontal surface in a truck, coefficient of static friction between the block and surface is 0.6.What is the force of friction on the block if the acceleration of the truck is 5 m/s^2?(g=10m/s^2)
Answer» 31. A block of mass 1 kg lies on a horizontal surface in a truck, coefficient of static friction between the block and surface is 0.6.What is the force of friction on the block if the acceleration of the truck is 5 m/s^2?(g=10m/s^2)

Discussion

8.	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

9.	One photon of a particular light having 200J energy can eject only one electron from a metal surface. How many electrons can be ejected when two photons of any other light having total amount of energy equal to 200J falls on it?(1) 0(2) 1(3) 2(4) 3
Answer» One photon of a particular light having 200J energy can eject only one electron from a metal surface. How many electrons can be ejected when two photons of any other light having total amount of energy equal to 200J falls on it? (1) 0 (2) 1 (3) 2 (4) 3

Discussion

10.	A cubical body of side 10cm each is floating into water. When 10gm mass is placed on the body,then calculate the length of body further immersed into the water due to this mass.
Answer» A cubical body of side 10cm each is floating into water. When 10gm mass is placed on the body,then calculate the length of body further immersed into the water due to this mass.

Discussion

11.	Find six rational no between 3and4
Answer» Find six rational no between 3and4

Discussion

12.	A particle is revolving in a circle of radius R with cons†an t speed v.Find the average velocity of the particle when the particle turns by angle theta
Answer» A particle is revolving in a circle of radius R with cons†an t speed v.Find the average velocity of the particle when the particle turns by angle theta

Discussion

13.	A block of mass m 2.0 kg moving at 2.0 ms collides head on with another block of equal mass kept at rest.(a) Find the maximum possible loss in kinetic energy due to the collision.(b) If the actual loss in kinetic energy is half of this maximum,find the coefficient of restitution.
Answer» A block of mass m 2.0 kg moving at $2.0 \frac{m}{s}$ collides head on with another block of equal mass kept at rest.(a) Find the maximum possible loss in kinetic energy due to the collision.(b) If the actual loss in kinetic energy is half of this maximum,find the coefficient of restitution.

Discussion

14.	A beam of rectangular cross-section is subjected to a vertical shear force of 100 kN the shear force carried by middle 13rd portion of the cross section is_____kN.48.14
Answer» A beam of rectangular cross-section is subjected to a vertical shear force of 100 kN the shear force carried by middle $\frac{1}{3}$ rd portion of the cross section is_____kN. 48.14

Discussion

15.	Answer the following questions: (a) In any ac circuit, is the applied instantaneous voltage equal to the algebraic sum of the instantaneous voltages across the series elements of the circuit? Is the same true for rms voltage? (b) A capacitor is used in the primary circuit of an induction coil. (c) An applied voltage signal consists of a superposition of a dc voltage and an ac voltage of high frequency. The circuit consists of an inductor and a capacitor in series. Show that the dc signal will appear across C and the ac signal across L. (d) A choke coil in series with a lamp is connected to a dc line. The lamp is seen to shine brightly. Insertion of an iron core in the choke causes no change in the lamp’s brightness. Predict the corresponding observations if the connection is to an ac line. (e) Why is choke coil needed in the use of fluorescent tubes with ac mains? Why can we not use an ordinary resistor instead of the choke coil?
Answer» Answer the following questions: (a) In any ac circuit, is the applied instantaneous voltage equal to the algebraic sum of the instantaneous voltages across the series elements of the circuit? Is the same true for rms voltage? (b) A capacitor is used in the primary circuit of an induction coil. (c) An applied voltage signal consists of a superposition of a dc voltage and an ac voltage of high frequency. The circuit consists of an inductor and a capacitor in series. Show that the dc signal will appear across C and the ac signal across L. (d) A choke coil in series with a lamp is connected to a dc line. The lamp is seen to shine brightly. Insertion of an iron core in the choke causes no change in the lamp’s brightness. Predict the corresponding observations if the connection is to an ac line. (e) Why is choke coil needed in the use of fluorescent tubes with ac mains? Why can we not use an ordinary resistor instead of the choke coil?

15.

Answer the following questions: (a) In any ac circuit, is the applied instantaneous voltage equal to the algebraic sum of the instantaneous voltages across the series elements of the circuit? Is the same true for rms voltage? (b) A capacitor is used in the primary circuit of an induction coil. (c) An applied voltage signal consists of a superposition of a dc voltage and an ac voltage of high frequency. The circuit consists of an inductor and a capacitor in series. Show that the dc signal will appear across C and the ac signal across L. (d) A choke coil in series with a lamp is connected to a dc line. The lamp is seen to shine brightly. Insertion of an iron core in the choke causes no change in the lamp’s brightness. Predict the corresponding observations if the connection is to an ac line. (e) Why is choke coil needed in the use of fluorescent tubes with ac mains? Why can we not use an ordinary resistor instead of the choke coil?

Answer»

Answer
the following questions:

(a) In any
ac circuit, is the applied instantaneous voltage equal to the
algebraic sum of the instantaneous voltages across the series
elements of the circuit? Is the same true for rms voltage?

(b)
A capacitor is used in the primary
circuit of an induction coil.

(c) An
applied voltage signal consists of a superposition of a dc voltage
and an ac voltage of high frequency. The circuit consists of an
inductor and a capacitor in series. Show that the dc signal will
appear across C and
the ac signal across L.

(d) A
choke coil in series with a lamp is connected to a dc line. The lamp
is seen to shine brightly. Insertion of an iron core in the choke
causes no change in the lamp’s brightness. Predict the
corresponding observations if the connection is to an ac line.

(e) Why is
choke coil needed in the use of fluorescent tubes with ac mains? Why
can we not use an ordinary resistor instead of the choke coil?

Discussion

16.	If →a,→b,→c are unit vectors and →b,→c are non-collinear vectors satisfying (→a,→b)=α,(→a,→c)=β and →a×(→b×→c)=→b+→c2, then cos(α+β)=
Answer» If $\to a, \to b, \to c$ are unit vectors and $\to b, \to c$ are non-collinear vectors satisfying $(\to a, \to b) = α, (\to a, \to c) = β$ and $\to a \times (\to b \times \to c) = \frac{\to b + \to c}{2},$ then $cos (α + β) =$

Discussion

17.	66.: An ideal gas at 27^° c is compressed adabatically to 8/27 of its original volume.The rise in temprature is (take gamma = 5/3) 1. 475^° C 2. 150^° C 3.275^° C 4.402^° C
Answer» 66.: An ideal gas at 27^° c is compressed adabatically to 8/27 of its original volume.The rise in temprature is (take gamma = 5/3) 1. 475^° C 2. 150^° C 3.275^° C 4.402^° C

Discussion

18.	Expansion during heating:
Answer» Expansion during heating:

Discussion

19.	The potential difference between points A and B, in a section of a circuit shown, is
Answer» The potential difference between points A and B, in a section of a circuit shown, is

Discussion

20.	A plank is moving with a velocity 4 m/s. A disc of radius 1 m rolls on it without slipping with an angular velocity of 3 rad/s as shown in figure. Then, the velocity of the centre of the disc (Vcm) is
Answer» A plank is moving with a velocity $4 m/s$ . A disc of radius $1 m$ rolls on it without slipping with an angular velocity of $3 rad/s$ as shown in figure. Then, the velocity of the centre of the disc $(V_{cm})$ is

Discussion

21.	A parallel plate capacitor having a separation between the plates d , plate area A and material with dielectric constant k has capacitance Co . Now one third of the material is replaced by another material with dielectric constant 2k, so that effectively there are two capacitors one with area A3, dielectric constant 2k and another with area 2A3 and dielectric constant k. If the capacitance of this new capacitor is C then the value of CC0 is:
Answer» A parallel plate capacitor having a separation between the plates $d$ , plate area $A$ and material with dielectric constant $k$ has capacitance $C_{o}$ . Now one third of the material is replaced by another material with dielectric constant $2 k$ , so that effectively there are two capacitors one with area $\frac{A}{3}$ , dielectric constant $2 k$ and another with area $\frac{2 A}{3}$ and dielectric constant $k$ . If the capacitance of this new capacitor is $C$ then the value of $\frac{C}{C_{0}}$ is:

Discussion

22.	The wave height generated on the surface of the reservoir having fetch length of 35 km and velocity of wind blowing on surface at 20 km /hr is _______m 0.847
Answer» The wave height generated on the surface of the reservoir having fetch length of 35 km and velocity of wind blowing on surface at 20 km /hr is _______m 0.847

Discussion

23.	80. The capacity and the energy stored in a charged parallel plate condenser with air btw its plates are respectively Co and Wo.IF the air is replaced by glass (dielectric
Answer» 80. The capacity and the energy stored in a charged parallel plate condenser with air btw its plates are respectively Co and Wo.IF the air is replaced by glass (dielectric

Discussion

24.	Three blocks m1,m2 and m3 of masses 8 kg,3 kg and 1 kg are placed in contact on a smooth surface. Forces F1=140 N and F2=20 N are acting on blocks m1 and m3 respectively as shown. The reaction between blocks m2 and m3 is
Answer» Three blocks $m_{1}, m_{2}$ and $m_{3}$ of masses $8 kg, 3 kg$ and $1 kg$ are placed in contact on a smooth surface. Forces $F_{1} = 140 N$ and $F_{2} = 20 N$ are acting on blocks $m_{1}$ and $m_{3}$ respectively as shown. The reaction between blocks $m_{2}$ and $m_{3}$ is

Discussion

25.	To a person running towards east with the speed 4km/hr. Rain appears to fall vertically. When he increases his speed to 6 km/hr rain appears to fall by making an angle 30^° with vertical. Find the actual velocity of rain.
Answer» To a person running towards east with the speed 4km/hr. Rain appears to fall vertically. When he increases his speed to 6 km/hr rain appears to fall by making an angle 30^° with vertical. Find the actual velocity of rain.

Discussion

26.	Is short electric dipole is placed at the origin and is directed along x-axis. At a point P far away from the dipole electric field is parallel to y axis. OP makes an angle theta with x-axis then tan(theta)=
Answer» Is short electric dipole is placed at the origin and is directed along x-axis. At a point P far away from the dipole electric field is parallel to y axis. OP makes an angle theta with x-axis then tan(theta)=

Discussion

27.	A disc revolves with a speed of 33 (1/3)rev/min, and has a radius of 15 cm. Two coins are placed at 4 cm and 14 cm away from the centre of the record. If the co-efficient of friction between the coins and the record is 0.15, which of the coins will revolve with the record ?
Answer» A disc revolves with a speed of 33 (1/3)rev/min, and has a radius of 15 cm. Two coins are placed at 4 cm and 14 cm away from the centre of the record. If the co-efficient of friction between the coins and the record is 0.15, which of the coins will revolve with the record ?

Discussion

28.	A bullet loses 1/20th of its velocity in passing through a plank. Find how many such uniform planks it would pass through before coming to rest assuming the retardation to be uniform?
Answer» A bullet loses 1/20th of its velocity in passing through a plank. Find how many such uniform planks it would pass through before coming to rest assuming the retardation to be uniform?

Discussion

29.	From the top of a tall mountain, a stone is dropped. One second later, another stone is projected downwards with velocity 20 ms−1. Find the distance from top where both stones meet.
Answer» From the top of a tall mountain, a stone is dropped. One second later, another stone is projected downwards with velocity $20 {ms}^{- 1}$ . Find the distance from top where both stones meet.

Discussion

30.	A particle executing SHM oscillates between two fixed points separated by 20 cm. If its maximum velocity is 30 cm/s, find its velocity when the displacement is 5cm from the mean position.
Answer» A particle executing SHM oscillates between two fixed points separated by $20 cm$ . If its maximum velocity is $30 cm/s$ , find its velocity when the displacement is $5 cm$ from the mean position.

Discussion

31.	The wheat stone bridge and its balance condition provides a practical method for determination of unknown resistance.
Answer» The wheat stone bridge and its balance condition provides a practical method for determination of unknown resistance.

Discussion

32.	A particle is moving on a circular path of radius R. Its centripetal acceleration vs time graph is given, then corresponding tangential acceleration vs time graph is best represented by
Answer» A particle is moving on a circular path of radius R. Its centripetal acceleration vs time graph is given, then corresponding tangential acceleration vs time graph is best represented by

Discussion

33.	A metre-long tube open at one end, with a movable piston at the other end, shows resonance with a fixed frequency source (a tuning fork of frequency 340 Hz) when the tube length is 25.5 cm or 79.3 cm. Estimate the speed of sound in air at the temperature of the experiment. The edge effects may be neglected
Answer» A metre-long tube open at one end, with a movable piston at the other end, shows resonance with a fixed frequency source (a tuning fork of frequency 340 Hz) when the tube length is 25.5 cm or 79.3 cm. Estimate the speed of sound in air at the temperature of the experiment. The edge effects may be neglected

Discussion

34.	What is black body radiation?
Answer» What is black body radiation?

Discussion

35.	Solids expand on heating because
Answer» Solids expand on heating because

Discussion

36.	The wavelength is 120 cm when the source is stationary. If the source is moving with velocity of 60m/sec towards the stationary observer, then the wavelength of the sound wave reaching to the observer will be (velocity of sound = 330 m/s)
Answer» The wavelength is 120 cm when the source is stationary. If the source is moving with velocity of $60 m / s e c$ towards the stationary observer, then the wavelength of the sound wave reaching to the observer will be (velocity of sound = $330 m / s$ )

Discussion

37.	An astronaut orbiting in a spaceship around the earth has a centripetal acceleration of 2.5 m/s2. The height of spaceship from earth's surface is (R=radius of earth and take g=10 m/s2).
Answer» An astronaut orbiting in a spaceship around the earth has a centripetal acceleration of $2.5 {m/s}^{2}$ . The height of spaceship from earth's surface is ( $R =$ radius of earth and take $g = 10 {m/s}^{2}$ ).

Discussion

38.	14. A magnetic dipole is placed at right angles to thedirection of lines of force of magnetic induction B. Ifit is rotated through an angle of 180^° , then the workdone is(1) 2MB(3) -2MB(2) MB(4) Zero
Answer» 14. A magnetic dipole is placed at right angles to thedirection of lines of force of magnetic induction B. Ifit is rotated through an angle of 180^° , then the workdone is(1) 2MB(3) -2MB(2) MB(4) Zero

Discussion

39.	Four identical charges are fixed on the periphery of a non conducting ring of radius R as shown. Ring is rotated with constant angular velocity ω wrt an axis perpendicular to pane of the ring and passing through the centre of the ring Force acting on any of the charge particle only due to the magnetic interaction between the charges is F=μ0q2ω24απ[√α+1α]Here α is an integer. Find the value of α
Answer» Four identical charges are fixed on the periphery of a non conducting ring of radius $R$ as shown. Ring is rotated with constant angular velocity $ω$ wrt an axis perpendicular to pane of the ring and passing through the centre of the ring Force acting on any of the charge particle only due to the magnetic interaction between the charges is $F = \frac{μ_{0} q^{2} ω^{2}}{4 α π} [\sqrt{α} + \frac{1}{α}]$ Here $α$ is an integer. Find the value of $α$

Discussion

40.	Two capacitors c1and c2 are changed to 120v and 200v respectively it is found that by connecting then together the potential on each one can be made zero then
Answer» Two capacitors c1and c2 are changed to 120v and 200v respectively it is found that by connecting then together the potential on each one can be made zero then

Discussion

41.	A cell of internal resistance r drives current through an external resistance R. The power delivered by the cell to the external resistance will be maximum when,
Answer» A cell of internal resistance $r$ drives current through an external resistance $R$ . The power delivered by the cell to the external resistance will be maximum when,

Discussion

42.	A light ray parallel to the x−axis strikes the outer reflecting surface of a sphere at a point (2,2,0). Its centre is at the point (0,0,–1). The unit vector along the direction of the reflected ray is x^i+y^j+z^k. Find the value of yzx2.
Answer» A light ray parallel to the $x -$ axis strikes the outer reflecting surface of a sphere at a point $(2, 2, 0)$ . Its centre is at the point $(0, 0, - 1)$ . The unit vector along the direction of the reflected ray is $x^i + y^j + z^k$ . Find the value of $\frac{y z}{x^{2}}$ .

Discussion

43.	Which of the following represents the correct graphical representation of the equation y=x2?
Answer» Which of the following represents the correct graphical representation of the equation $y = x^{2}$ ?

Discussion

44.	Two cylindrical rods of lengths l1 and l2, radii r1 and r2 have thermal conductivities k1 and k2 respectively. The ends of the rods are maintained at the same temperature difference. If l1=2l2 and r1=r22, the rates of heat flow in them will be the same if k1k2 is
Answer» Two cylindrical rods of lengths $l_{1}$ and $l_{2}$ , radii $r_{1}$ and $r_{2}$ have thermal conductivities $k_{1}$ and $k_{2}$ respectively. The ends of the rods are maintained at the same temperature difference. If $l_{1} = 2 l_{2}$ and $r_{1} = \frac{r_{2}}{2}$ , the rates of heat flow in them will be the same if $\frac{k_{1}}{k_{2}}$ is

Discussion

45.	How tan 90 is infinite? Explain with a rough diagram.
Answer» How tan 90 is infinite? Explain with a rough diagram.

Discussion

46.	A ray of light travelling in the direction 12(^i+√3^j) is incident on a plane mirror. After reflection, it travels along the direction 12(^i−√3^j). The angle of incidence is
Answer» A ray of light travelling in the direction $\frac{1}{2} (^i + \sqrt{3}^j)$ is incident on a plane mirror. After reflection, it travels along the direction $\frac{1}{2} (^i - \sqrt{3}^j)$ . The angle of incidence is

Discussion

47.	Two positively charged spheres of masses m1 and m2 , are suspended from a common point at the ceiling by identical insulating massless strings of length l. Charges on the two spheres are q1 and q2 , respectively. At equilibrium both strings make the same angle θ with the vertical. Then
Answer» Two positively charged spheres of masses $m_{1}$ and $m_{2}$ , are suspended from a common point at the ceiling by identical insulating massless strings of length l. Charges on the two spheres are $q_{1}$ and $q_{2}$ , respectively. At equilibrium both strings make the same angle $θ$ with the vertical. Then

Discussion

48.	The velocity of a projectile at point of projection O is 30i+40j then what is velocity at point of arrival??
Answer» The velocity of a projectile at point of projection O is 30i+40j then what is velocity at point of arrival??

Discussion

49.	A car begins from rest at time t=0 and then accelerates along a straight track during the interval 0≤t≤2 s during which velocity varies as v=kt2 . Thereafter it moves with constant velocity as shown in the graph. A coin is initially at rest on the floor of the car. At t=1 s, the coin begins to slip and stop slipping at t=3 s. The co-efficient of static friction between the floor and the coin is ( Take g=10 m/s2)
Answer» A car begins from rest at time $t = 0$ and then accelerates along a straight track during the interval $0 \leq t \leq 2 s$ during which velocity varies as $v = k t^{2}$ . Thereafter it moves with constant velocity as shown in the graph. A coin is initially at rest on the floor of the car. At $t = 1 s$ , the coin begins to slip and stop slipping at $t = 3 s$ . The co-efficient of static friction between the floor and the coin is $($ Take $g = 10 {m/s}^{2})$

Discussion

50.	Diameter of steel rod fixed between two rigid supports is 20 mm. Find the stress in the rod when the temperature increases by 80∘C. (Take Young's modulus, Y=2×1011 N/m2 and thermal expansion coefficient ,α=12×10−6/ ∘C)
Answer» Diameter of steel rod fixed between two rigid supports is $20 mm$ . Find the stress in the rod when the temperature increases by $80^{\circ} C$ . $($ Take Young's modulus, $Y = 2 \times 10^{11} {N/m}^{2}$ and thermal expansion coefficient , $α = 12 \times 10^{- 6} /^{\circ} C)$

Discussion

Explore topic-wise InterviewSolutions in Current Affairs.

During oscillation velocity of particle is maximum at mean position .How ?

A p n photo diode is made of a material with a band gap of 2.0 e v . the minimum frequency of the radiation that can be absorbed by the material is nearly

A particle returns to the starting point after 10 s if the rate of change of velocity during the motion is constant, then its location after 7 s will be same as that after

The horn of a car emits sound with a dominant frequency of 2400 Hz. What will be the apparent dominant frequency heard by a person standing on the road in front of the car if the car is approaching at 18.0 km/h ? Speed of sound in air = 340 m/s.

A person looking at a person wearing a shirt with a patterncomprising vertical and horizontal lines is able to see the verticallines more distinctly than the horizontal ones. What is this defect due to? How is such a defect of vision corrected?

31. A block of mass 1 kg lies on a horizontal surface in a truck, coefficient of static friction between the block and surface is 0.6.What is the force of friction on the block if the acceleration of the truck is 5 m/s^2?(g=10m/s^2)

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.

One photon of a particular light having 200J energy can eject only one electron from a metal surface. How many electrons can be ejected when two photons of any other light having total amount of energy equal to 200J falls on it?(1) 0(2) 1(3) 2(4) 3

A cubical body of side 10cm each is floating into water. When 10gm mass is placed on the body,then calculate the length of body further immersed into the water due to this mass.

Find six rational no between 3and4

A particle is revolving in a circle of radius R with cons†an t speed v.Find the average velocity of the particle when the particle turns by angle theta

A block of mass m 2.0 kg moving at 2.0 ms collides head on with another block of equal mass kept at rest.(a) Find the maximum possible loss in kinetic energy due to the collision.(b) If the actual loss in kinetic energy is half of this maximum,find the coefficient of restitution.

A beam of rectangular cross-section is subjected to a vertical shear force of 100 kN the shear force carried by middle 13rd portion of the cross section is_____kN.48.14

If →a,→b,→c are unit vectors and →b,→c are non-collinear vectors satisfying (→a,→b)=α,(→a,→c)=β and →a×(→b×→c)=→b+→c2, then cos(α+β)=

66.: An ideal gas at 27^° c is compressed adabatically to 8/27 of its original volume.The rise in temprature is (take gamma = 5/3) 1. 475^° C 2. 150^° C 3.275^° C 4.402^° C

Expansion during heating:

The potential difference between points A and B, in a section of a circuit shown, is

A plank is moving with a velocity 4 m/s. A disc of radius 1 m rolls on it without slipping with an angular velocity of 3 rad/s as shown in figure. Then, the velocity of the centre of the disc (Vcm) is

The wave height generated on the surface of the reservoir having fetch length of 35 km and velocity of wind blowing on surface at 20 km /hr is _______m 0.847

80. The capacity and the energy stored in a charged parallel plate condenser with air btw its plates are respectively Co and Wo.IF the air is replaced by glass (dielectric

Three blocks m1,m2 and m3 of masses 8 kg,3 kg and 1 kg are placed in contact on a smooth surface. Forces F1=140 N and F2=20 N are acting on blocks m1 and m3 respectively as shown. The reaction between blocks m2 and m3 is

To a person running towards east with the speed 4km/hr. Rain appears to fall vertically. When he increases his speed to 6 km/hr rain appears to fall by making an angle 30^° with vertical. Find the actual velocity of rain.

Is short electric dipole is placed at the origin and is directed along x-axis. At a point P far away from the dipole electric field is parallel to y axis. OP makes an angle theta with x-axis then tan(theta)=

A disc revolves with a speed of 33 (1/3)rev/min, and has a radius of 15 cm. Two coins are placed at 4 cm and 14 cm away from the centre of the record. If the co-efficient of friction between the coins and the record is 0.15, which of the coins will revolve with the record ?

A bullet loses 1/20th of its velocity in passing through a plank. Find how many such uniform planks it would pass through before coming to rest assuming the retardation to be uniform?

From the top of a tall mountain, a stone is dropped. One second later, another stone is projected downwards with velocity 20 ms−1. Find the distance from top where both stones meet.

A particle executing SHM oscillates between two fixed points separated by 20 cm. If its maximum velocity is 30 cm/s, find its velocity when the displacement is 5cm from the mean position.

The wheat stone bridge and its balance condition provides a practical method for determination of unknown resistance.

A particle is moving on a circular path of radius R. Its centripetal acceleration vs time graph is given, then corresponding tangential acceleration vs time graph is best represented by

What is black body radiation?

Solids expand on heating because

The wavelength is 120 cm when the source is stationary. If the source is moving with velocity of 60m/sec towards the stationary observer, then the wavelength of the sound wave reaching to the observer will be (velocity of sound = 330 m/s)

An astronaut orbiting in a spaceship around the earth has a centripetal acceleration of 2.5 m/s2. The height of spaceship from earth's surface is (R=radius of earth and take g=10 m/s2).

14. A magnetic dipole is placed at right angles to thedirection of lines of force of magnetic induction B. Ifit is rotated through an angle of 180^° , then the workdone is(1) 2MB(3) -2MB(2) MB(4) Zero

Two capacitors c1and c2 are changed to 120v and 200v respectively it is found that by connecting then together the potential on each one can be made zero then

A cell of internal resistance r drives current through an external resistance R. The power delivered by the cell to the external resistance will be maximum when,

A light ray parallel to the x−axis strikes the outer reflecting surface of a sphere at a point (2,2,0). Its centre is at the point (0,0,–1). The unit vector along the direction of the reflected ray is x^i+y^j+z^k. Find the value of yzx2.

Which of the following represents the correct graphical representation of the equation y=x2?

Two cylindrical rods of lengths l1 and l2, radii r1 and r2 have thermal conductivities k1 and k2 respectively. The ends of the rods are maintained at the same temperature difference. If l1=2l2 and r1=r22, the rates of heat flow in them will be the same if k1k2 is

How tan 90 is infinite? Explain with a rough diagram.

A ray of light travelling in the direction 12(^i+√3^j) is incident on a plane mirror. After reflection, it travels along the direction 12(^i−√3^j). The angle of incidence is

Two positively charged spheres of masses m1 and m2 , are suspended from a common point at the ceiling by identical insulating massless strings of length l. Charges on the two spheres are q1 and q2 , respectively. At equilibrium both strings make the same angle θ with the vertical. Then

The velocity of a projectile at point of projection O is 30i+40j then what is velocity at point of arrival??

Diameter of steel rod fixed between two rigid supports is 20 mm. Find the stress in the rod when the temperature increases by 80∘C. (Take Young's modulus, Y=2×1011 N/m2 and thermal expansion coefficient ,α=12×10−6/ ∘C)