50278 + Interview Questions in Physics

1.	∫ex(x−1)(x−ln x)x2dx is equal to
Answer» $\int \frac{e^{x} (x - 1) (x - l n x)}{x^{2}} d x$ is equal to

Discussion

2.	Why does resistivity and temperature varies- 1.directly to metals 2.inversely to semiconductors 3.doesnot varies with temperature in alloys \|\|Explain all three conditions in details.\|\|
Answer» Why does resistivity and temperature varies- 1.directly to metals 2.inversely to semiconductors 3.doesnot varies with temperature in alloys \|\|Explain all three conditions in details.\|\|

Discussion

3.	Two sources of sound A and B produces the wave of 350 Hz, they vibrate in the same phase. The particle P is vibrating under the influence of these two waves, if the amplitudes at the point P produced by the two waves is 0.3 mm and 0.4 mm, then the resultant amplitude of the point P will be when AP - BP = 25 cm and the velocity of sound is 350 m/sec
Answer» Two sources of sound A and B produces the wave of 350 Hz, they vibrate in the same phase. The particle P is vibrating under the influence of these two waves, if the amplitudes at the point P produced by the two waves is 0.3 mm and 0.4 mm, then the resultant amplitude of the point P will be when AP - BP = 25 cm and the velocity of sound is 350 m/sec

Discussion

4.	A biconvex lens of a focal length of 10 cm is to be made from a glass material. If the refractive index of the material is 1.5, what must be the radius of curvature of the surface of the lens? a) 0.1 m b) 0.15 m c) 0.20 m d) 0.30 m
Answer» A biconvex lens of a focal length of 10 cm is to be made from a glass material. If the refractive index of the material is 1.5, what must be the radius of curvature of the surface of the lens? a) 0.1 m b) 0.15 m c) 0.20 m d) 0.30 m

4.

A biconvex lens of a focal length of 10 cm is to be made from a glass material. If the refractive index of the material is 1.5, what must be the radius of curvature of the surface of the lens? a) 0.1 m b) 0.15 m c) 0.20 m d) 0.30 m

Answer»

A biconvex lens of a focal length of 10 cm is to be made from a glass material. If the refractive index of the material is 1.5, what must be the radius of curvature of the surface of the lens?

a) 0.1 m

b) 0.15 m

c) 0.20 m

d) 0.30 m

Discussion

5.	In a 1D motion, ball B is ahead of A. Ball A is moving with a speed of 10 m/s towards B and ball B is moving with speed 15 m/s towards ball A. After the collision, ball A starts moving with a speed of 5 m/s towards ball B and ball B starts moving with a speed of 20 m/s away from A. Find the coefficient of restitution (e).
Answer» In a $1 D$ motion, ball $B$ is ahead of $A$ . Ball $A$ is moving with a speed of $10 m/s$ towards $B$ and ball $B$ is moving with speed $15 m/s$ towards ball $A$ . After the collision, ball $A$ starts moving with a speed of $5 m/s$ towards ball $B$ and ball $B$ starts moving with a speed of $20 m/s$ away from $A$ . Find the coefficient of restitution $(e)$ .

Discussion

6.	A block of mass M is pulled along a horizontal surface by applying a force at an angle with the horizontal. The friction coefficient between the block and the surface is μ. If the block travels at a uniform velocity, then the work done by this applied force during a displacement d of the block is—
Answer» A block of mass M is pulled along a horizontal surface by applying a force at an angle with the horizontal. The friction coefficient between the block and the surface is $μ$ . If the block travels at a uniform velocity, then the work done by this applied force during a displacement d of the block is—

Discussion

7.	A bullet of mass 10 g moving horizontally at a speed of 50√7 ms/ strikes a block of mass 490 g kept on a frictionless track as shown in figure (9-E17). the bullet remains inside the block and the system proceeds towards the semicircular track of radius 0.2 m. Where will the block strike the horizontal part after leaving the semicircular track ?
Answer» A bullet of mass 10 g moving horizontally at a speed of $50 \sqrt{7} m s /$ strikes a block of mass 490 g kept on a frictionless track as shown in figure (9-E17). the bullet remains inside the block and the system proceeds towards the semicircular track of radius 0.2 m. Where will the block strike the horizontal part after leaving the semicircular track ?

7.

A bullet of mass 10 g moving horizontally at a speed of 50√7 ms/ strikes a block of mass 490 g kept on a frictionless track as shown in figure (9-E17). the bullet remains inside the block and the system proceeds towards the semicircular track of radius 0.2 m. Where will the block strike the horizontal part after leaving the semicircular track ?

Answer»

A bullet of mass 10 g moving horizontally at a speed of $50 \sqrt{7} m s /$ strikes a block of mass 490 g kept on a frictionless track as shown in figure (9-E17). the bullet remains inside the block and the system proceeds towards the semicircular track of radius 0.2 m. Where will the block strike the horizontal part after leaving the semicircular track ?

Discussion

8.	A hollow sphere of radius R lies on a smooth horizontal surface. It is pulled by a horizontal force acting tangentially from the highest point. Find the distance travelled by the sphere during the time it makes one full rotation.
Answer» A hollow sphere of radius R lies on a smooth horizontal surface. It is pulled by a horizontal force acting tangentially from the highest point. Find the distance travelled by the sphere during the time it makes one full rotation.

Discussion

9.	A standing wave y=2Asinkxcosωt is set up in the wire AB fixed at both ends of two vertical walls. The region between the walls contains a constant magnetic field B The wire is found to vibrate in the third harmonic. The maximum emf induced between the ends is xBAωk, where the value of x is . (Write upto two digits after the decimal point.)
Answer» A standing wave $y = 2 A sin k x cos ω t$ is set up in the wire AB fixed at both ends of two vertical walls. The region between the walls contains a constant magnetic field $B$ The wire is found to vibrate in the third harmonic. The maximum emf induced between the ends is $\frac{x B A ω}{k}$ , where the value of x is . (Write upto two digits after the decimal point.)

Discussion

10.	A heavy but uniform rope of length L is suspended from a ceiling. (a) Write the velocity of a transverse wave travelling on the string as a function of the distance from the lower end. (b). If the rope is given a sudden sideways jerk at the bottom, how long will it take for the pulse to reach the celiling ? (c) A particle is dropped from the ceiling at the instant the bottom end is given the jerk. Where will the particle meet the pulse ?
Answer» A heavy but uniform rope of length L is suspended from a ceiling. (a) Write the velocity of a transverse wave travelling on the string as a function of the distance from the lower end. (b). If the rope is given a sudden sideways jerk at the bottom, how long will it take for the pulse to reach the celiling ? (c) A particle is dropped from the ceiling at the instant the bottom end is given the jerk. Where will the particle meet the pulse ?

Discussion

11.	An automobile moves on a road with a speed of 54 km/hr. The radius of its wheels is 0.45 m and the moment of inertia of the wheel about its axis of rotation is 3 kg-m2. If the vehicle is brought to rest in 15 s, the magnitude of average torque transmitted by its brakes to the wheel is
Answer» An automobile moves on a road with a speed of $54 km/hr$ . The radius of its wheels is $0.45 m$ and the moment of inertia of the wheel about its axis of rotation is $3 {kg-m}^{2}$ . If the vehicle is brought to rest in $15 s$ , the magnitude of average torque transmitted by its brakes to the wheel is

Discussion

12.	A fan is rotating with angular velocity 100 rev/sec. Then, it is switched off. It takes 5 minutes to stop. Find the average angular velocity during this interval. (correct answer + 1, wrong answer - 0.25)
Answer» A fan is rotating with angular velocity $100 rev/sec$ . Then, it is switched off. It takes $5$ minutes to stop. Find the average angular velocity during this interval. (correct answer + 1, wrong answer - 0.25)

Discussion

13.	Angle of minimum deviation for a prism of refractive index 1.5 is equal to the angle of prism. The angle of prism is (cos41∘=0.75)
Answer» Angle of minimum deviation for a prism of refractive index 1.5 is equal to the angle of prism. The angle of prism is $(c o s 41^{\circ} = 0.75)$

Discussion

14.	The resistivity vs. Temperature variation of a certain material is shown below. At 2∘C, this material will act as?
Answer» The resistivity vs. Temperature variation of a certain material is shown below. At $2^{\circ} C$ , this material will act as?

Discussion

15.	A particle of mass m is attached to three springs A, B and C of equal force constants k as shown in figure (12-E6). If the particle is pushed slightly against the spring C and released, find the time period of oscillation.
Answer» A particle of mass m is attached to three springs A, B and C of equal force constants k as shown in figure (12-E6). If the particle is pushed slightly against the spring C and released, find the time period of oscillation.

15.

A particle of mass m is attached to three springs A, B and C of equal force constants k as shown in figure (12-E6). If the particle is pushed slightly against the spring C and released, find the time period of oscillation.

Answer»

A particle of mass m is attached to three springs A, B and C of equal force constants k as shown in figure (12-E6). If the particle is pushed slightly against the spring C and released, find the time period of oscillation.

Discussion

16.	A block of mass m slips on a rough horizontal table under the action of a horizontal force applied to it. The coefficient of friction between the block and the table is μ the table does not move on the floor. Find the total frictional force appied by the floor on the legs of the table. Do you need the friction coefficient between the table and the floor or the mass of the table?
Answer» A block of mass m slips on a rough horizontal table under the action of a horizontal force applied to it. The coefficient of friction between the block and the table is $μ$ the table does not move on the floor. Find the total frictional force appied by the floor on the legs of the table. Do you need the friction coefficient between the table and the floor or the mass of the table?

Discussion

17.	Which of the following principles are involved in the design of the Van de Graaf generator?
Answer» Which of the following principles are involved in the design of the Van de Graaf generator?

Discussion

18.	Water failing from a 50 m high fall is to be used for generating electric energy. If 1.8 ×105 Kg of water falls per hour and half the gravitational potential energy can be converted into electric energy, how many 100 W lamps can be lit?Take g=10 m/s2
Answer» Water failing from a 50 m high fall is to be used for generating electric energy. If 1.8 $\times$ $10^{5}$ Kg of water falls per hour and half the gravitational potential energy can be converted into electric energy, how many 100 W lamps can be lit?Take g=10 $m / s^{2}$

Discussion

19.	Three concentric spheres are shown in figure. Find the potential on surface of shell B. Charge on A, B and C are 3Q,−2Q and Q respectively.
Answer» Three concentric spheres are shown in figure. Find the potential on surface of shell $B$ . Charge on $A$ , $B$ and $C$ are $3 Q, - 2 Q$ and $Q$ respectively.

Discussion

20.	One end of a copper rod of uniform cross section and of length 1.5 m is kept in contact with ice and the other end with water at 100∘C. At what point along its length should a temperature of 200∘C be maintained so that in steady state, the mass of ice melting be equal to that the steam produced in same interval of time? Assume that the whole system is insulate from surroundings. Latent heat of fusion of ice and vaporization of water are 80 cal/g and 540 cal/g, respectively.
Answer» One end of a copper rod of uniform cross section and of length 1.5 m is kept in contact with ice and the other end with water at $100^{\circ} C$ . At what point along its length should a temperature of $200^{\circ} C$ be maintained so that in steady state, the mass of ice melting be equal to that the steam produced in same interval of time? Assume that the whole system is insulate from surroundings. Latent heat of fusion of ice and vaporization of water are 80 cal/g and 540 cal/g, respectively.

20.

One end of a copper rod of uniform cross section and of length 1.5 m is kept in contact with ice and the other end with water at 100∘C. At what point along its length should a temperature of 200∘C be maintained so that in steady state, the mass of ice melting be equal to that the steam produced in same interval of time? Assume that the whole system is insulate from surroundings. Latent heat of fusion of ice and vaporization of water are 80 cal/g and 540 cal/g, respectively.

Answer»

One end of a copper rod of uniform cross section and of length 1.5 m is kept in contact with ice and the other end with water at $100^{\circ} C$ . At what point along its length should a temperature of $200^{\circ} C$ be maintained so that in steady state, the mass of ice melting be equal to that the steam produced in same interval of time? Assume that the whole system is insulate from surroundings. Latent heat of fusion of ice and vaporization of water are 80 cal/g and 540 cal/g, respectively.

Discussion

21.	With what speed should a body be thrown upwards so that the distance traversed in 5th second and 6th second are equal? (Take g=9.8 m/s2)
Answer» With what speed should a body be thrown upwards so that the distance traversed in $5^{t h}$ second and $6^{t h}$ second are equal? (Take $g = 9.8 m / s^{2}$ )

Discussion

22.	How the graphical representation of spring force come ?
Answer» How the graphical representation of spring force come ?

Discussion

23.	A block A (5 kg) rests over another block B (3 kg) placed over a smooth horizontal surface. There is friction between A and B. A horizontal force F1 gradually increasing from zero to a maximum is applied to A so that the blocks move together without relative motion. Instead of this another horizontal force F2, gradually increasing from zero to a maximum is applied to B so that the blocks move together without relative motion. Then
Answer» A block $A (5 kg)$ rests over another block $B (3 kg)$ placed over a smooth horizontal surface. There is friction between $A$ and $B$ . A horizontal force $F_{1}$ gradually increasing from zero to a maximum is applied to $A$ so that the blocks move together without relative motion. Instead of this another horizontal force $F_{2}$ , gradually increasing from zero to a maximum is applied to $B$ so that the blocks move together without relative motion. Then

Discussion

24.	Four short dipoles each of dipole moment p are placed at the vertices of a square of side a. The direction of the dipole moments are shown in the figure.
Answer» Four short dipoles each of dipole moment p are placed at the vertices of a square of side a. The direction of the dipole moments are shown in the figure.

Discussion

25.	A circular portion of radius R/2 is cut from a uniform circular disc of mass M and radius R as shown in the figure. Find the moment of inertia of the remaining body about an axis which is perpendicular to the plane of the disc and touches a point on the circumference of the disc as shown.
Answer» A circular portion of radius R/2 is cut from a uniform circular disc of mass M and radius R as shown in the figure. Find the moment of inertia of the remaining body about an axis which is perpendicular to the plane of the disc and touches a point on the circumference of the disc as shown.

Discussion

26.	The resistance between points M and N in the circuit is
Answer» The resistance between points M and N in the circuit is

Discussion

27.	A pulse as shown in figure is moving fowards negative x - axis at v = 1 cm/s in a stretched string. End at (0, 0) is open. And given snapshot is at t = 0 sec at t = 3 sec. y - coordinate of string at x = 0.5 cm is cm.
Answer» A pulse as shown in figure is moving fowards negative x - axis at v = 1 cm/s in a stretched string. End at (0, 0) is open. And given snapshot is at t = 0 sec at t = 3 sec. y - coordinate of string at x = 0.5 cm is cm.

Discussion

28.	An object of specific gravity ρ is hung from a thin steel wire. The fundamental frequency (in Hz) is 300Hz. The object is immersed in water with specific gravity ρw, so that one half its volume is submerged. The new fundamental frequency (in Hz) is
Answer» An object of specific gravity ρ is hung from a thin steel wire. The fundamental frequency (in Hz) is 300Hz. The object is immersed in water with specific gravity $ρ_{w}$ , so that one half its volume is submerged. The new fundamental frequency (in Hz) is

Discussion

29.	A uniform slender rod of length L, cross section area A and Young's modulus Y is acted upon by forces as shown in figure. If elongation of rod is nFLAY, then n is (Write upto two digits after the decimal point.)
Answer» A uniform slender rod of length L, cross section area A and Young's modulus Y is acted upon by forces as shown in figure. If elongation of rod is $\frac{n F L}{A Y}$ , then n is (Write upto two digits after the decimal point.)

Discussion

30.	The photosensitive metal is first irradiated with the radiation of wavelength 400 mm and then with radiation of wavelength 800 nm. The change in the maximum kinetic energy of the photoelectron assuming that both wavelengths can cause photoelectric emission, is
Answer» The photosensitive metal is first irradiated with the radiation of wavelength 400 mm and then with radiation of wavelength 800 nm. The change in the maximum kinetic energy of the photoelectron assuming that both wavelengths can cause photoelectric emission, is

Discussion

31.	For an atom having atomic number z. Match the following: Column−IColumn−II(A) Radius of orbit(p) is proportional to z(B) Current associated due to orbita lmotion of electron(q) is inversely proportional to z.(C) Magnetic field at the centre due to orbital motion of electron(r) is proportional to z2.(D) Velocity of an electron(s) is proportional to z3
Answer» For an atom having atomic number z. Match the following: $\begin{matrix} C o l u m n - I & C o l u m n - I I (A) R a d i u s o f o r b i t & (p) i s p r o p o r t i o n a l t o z (B) C u r r e n t a s s o c i a t e d d u e t o o r b i t a l m o t i o n o f e l e c t r o n & (q) i s i n v e r s e l y p r o p o r t i o n a l t o z . (C) M a g n e t i c f i e l d a t t h e c e n t r e d u e t o o r b i t a l m o t i o n o f e l e c t r o n & (r) i s p r o p o r t i o n a l t o z^{2} . (D) V e l o c i t y o f a n e l e c t r o n & (s) i s p r o p o r t i o n a l t o z^{3} \end{matrix}$

31.

For an atom having atomic number z. Match the following: Column−IColumn−II(A) Radius of orbit(p) is proportional to z(B) Current associated due to orbita lmotion of electron(q) is inversely proportional to z.(C) Magnetic field at the centre due to orbital motion of electron(r) is proportional to z2.(D) Velocity of an electron(s) is proportional to z3

Answer»

For an atom having atomic number z.
Match the following:

$\begin{matrix} C o l u m n - I & C o l u m n - I I (A) R a d i u s o f o r b i t & (p) i s p r o p o r t i o n a l t o z (B) C u r r e n t a s s o c i a t e d d u e t o o r b i t a l m o t i o n o f e l e c t r o n & (q) i s i n v e r s e l y p r o p o r t i o n a l t o z . (C) M a g n e t i c f i e l d a t t h e c e n t r e d u e t o o r b i t a l m o t i o n o f e l e c t r o n & (r) i s p r o p o r t i o n a l t o z^{2} . (D) V e l o c i t y o f a n e l e c t r o n & (s) i s p r o p o r t i o n a l t o z^{3} \end{matrix}$

Discussion

32.	An ac source of angular frequency ω is fed across a resistor R and a capacitor C in series. The current registered isi. If now the frequency of source is changed to ω/3 (but maintaining the same voltage), the current in then circuit is found to be halved. Calculate the ratio of reactance to resistance at the original frequency ω
Answer» An ac source of angular frequency $ω$ is fed across a resistor R and a capacitor C in series. The current registered isi. If now the frequency of source is changed to $ω / 3$ (but maintaining the same voltage), the current in then circuit is found to be halved. Calculate the ratio of reactance to resistance at the original frequency $ω$

Discussion

33.	As shown in the figure a person is pulling a mass 2 kg from ground on a fixed rough surface up to the top of the surface with the help of a light inextensible string. Find the work done (in Joule) by tension in the string if height of the surface is 1 m from ground, length of base of the surface is 2.5 m and friction coefficient is 0.4. Assume that the block is pulled with negligible velocity.
Answer» As shown in the figure a person is pulling a mass 2 kg from ground on a fixed rough surface up to the top of the surface with the help of a light inextensible string. Find the work done (in Joule) by tension in the string if height of the surface is 1 m from ground, length of base of the surface is 2.5 m and friction coefficient is 0.4. Assume that the block is pulled with negligible velocity.

33.

As shown in the figure a person is pulling a mass 2 kg from ground on a fixed rough surface up to the top of the surface with the help of a light inextensible string. Find the work done (in Joule) by tension in the string if height of the surface is 1 m from ground, length of base of the surface is 2.5 m and friction coefficient is 0.4. Assume that the block is pulled with negligible velocity.

Answer»

As shown in the figure a person is pulling a mass 2 kg from ground on a fixed rough surface up to the top of the surface with the help of a light inextensible string. Find the work done (in Joule) by tension in the string if height of the surface is 1 m from ground, length of base of the surface is 2.5 m and friction coefficient is 0.4. Assume that the block is pulled with negligible velocity.

Discussion

34.	A ball is thrown vertically upward with a velocity of 10 m/s from the top of a tower of height of 50 m. Find the time taken by the ball to reach a height 10 m from the ground. (Take g=10 m/s2)
Answer» A ball is thrown vertically upward with a velocity of $10 m/s$ from the top of a tower of height of $50 m$ . Find the time taken by the ball to reach a height $10 m$ from the ground. (Take $g = 10 {m/s}^{2}$ )

Discussion

35.	A capacitor of capacitance C0 is charged to a potential V0 and then isolated. A small capacitor C is then charged from C0, discharged and charged again; the process being repeated n times. Due to this, potential of the larger capacitor is decreased to V. The value of C is
Answer» A capacitor of capacitance $C_{0}$ is charged to a potential $V_{0}$ and then isolated. A small capacitor $C$ is then charged from $C_{0}$ , discharged and charged again; the process being repeated n times. Due to this, potential of the larger capacitor is decreased to $V$ . The value of $C$ is

Discussion

36.	When the ratio of the minimum velocity to the maximum velocity is 12 in a projectile motion, the angle of projection of projectile is?
Answer» When the ratio of the minimum velocity to the maximum velocity is $\frac{1}{2}$ in a projectile motion, the angle of projection of projectile is?

Discussion

37.	Two bodies M and N of equal masses are suspended from two separate springs of the spring constant k1 and k2 respectively. If the two bodies oscillate vertically such that their maximum velocities are equal, the ratio of the amplitude of vibration of M to that on N is
Answer» Two bodies M and N of equal masses are suspended from two separate springs of the spring constant $k_{1}$ and $k_{2}$ respectively. If the two bodies oscillate vertically such that their maximum velocities are equal, the ratio of the amplitude of vibration of M to that on N is

Discussion

38.	A line makes angles 60o with Y-axis and 45o with Z-axis, the direction cosines of this line are:
Answer» A line makes angles 60^o with Y-axis and 45^o with Z-axis, the direction cosines of this line are:

Discussion

39.	How can we convert a galvanometer into an ammeter of given range?
Answer» How can we convert a galvanometer into an ammeter of given range?

Discussion

40.	A solid sphere of radius 5 cm floats in water. If a maximum load of 0.1 kg can be put on it without wetting the load, find the specific gravity of the material of the sphere.
Answer» A solid sphere of radius 5 cm floats in water. If a maximum load of 0.1 kg can be put on it without wetting the load, find the specific gravity of the material of the sphere.

Discussion

41.	Show that the speed of an electron in 1st Bohr orbit is c137, where c is the speed of light.
Answer» Show that the speed of an electron in 1st Bohr orbit is $\frac{c}{137}$ , where c is the speed of light.

Discussion

42.	Mass M is divided into two parts m1and m2.fr a given separation the ratio of m1/M forwhich the gravitational attraction between the two parts becomes maximum is 1:1 1:2 1:3 1:4 Ans option 2 how?
Answer» Mass M is divided into two parts m1and m2.fr a given separation the ratio of m1/M forwhich the gravitational attraction between the two parts becomes maximum is 1:1 1:2 1:3 1:4 Ans option 2 how?

42.

Mass M is divided into two parts m1and m2.fr a given separation the ratio of m1/M forwhich the gravitational attraction between the two parts becomes maximum is 1:1 1:2 1:3 1:4 Ans option 2 how?

Answer»

Mass M is divided into two parts m1and m2.fr a given separation the ratio of m1/M forwhich the gravitational attraction between the two parts becomes maximum is

1:1

1:2

1:3

1:4

Ans option 2 how?

Discussion

43.	what is the exact definition of dimension
Answer» what is the exact definition of dimension

Discussion

44.	Two stones A and B are projected simultaneously as shown in figure. It has been observed that both the stones reach the ground at the same place after 7 seconds of their projection. The difference in the vertical components of their initial velocities in m/s is (g=9.8 m/s2)
Answer» Two stones A and B are projected simultaneously as shown in figure. It has been observed that both the stones reach the ground at the same place after $7$ seconds of their projection. The difference in the vertical components of their initial velocities in $m/s$ is ( $g = 9.8 {m/s}^{2}$ )

Discussion

45.	Two particles are executing simple harmonic motion of the same amplitude A and angular frequency ω along the x−axis. Their mean position is separated by distance Xo(Xo>A). If the maximum separation between them is (Xo+A), the phase difference between their motion is
Answer» Two particles are executing simple harmonic motion of the same amplitude $A$ and angular frequency $ω$ along the $x -$ axis. Their mean position is separated by distance $X_{o} (X_{o} > A)$ . If the maximum separation between them is $(X_{o} + A)$ , the phase difference between their motion is

Discussion

46.	A plank of mass 10 kg rests on a smooth horizontal surface.Two blocks A and B of masses ma = 2 kg and mb =1 kg lies at a distance of 3 m on the plank. The friction coefficient between the blocks and plank are fa=0.3 and fb=0.1.Now a force F=15 N is applied to the plank in horizontal direction.Find the time (in sec) after which block A collides with B.
Answer» A plank of mass 10 kg rests on a smooth horizontal surface.Two blocks A and B of masses m_a = 2 kg and m_b =1 kg lies at a distance of 3 m on the plank. The friction coefficient between the blocks and plank are f_a=0.3 and f_b=0.1.Now a force F=15 N is applied to the plank in horizontal direction.Find the time (in sec) after which block A collides with B.

Discussion

47.	Best physics reference books for JEE.
Answer» Best physics reference books for JEE.

Discussion

48.	A gaseous mixture consists of 16 g He and 16 g O2. The ratio of specific heats CpCv of the mixture is
Answer» A gaseous mixture consists of $16 g H e$ and $16 g O_{2}$ . The ratio of specific heats $\frac{C_{p}}{C_{v}}$ of the mixture is

Discussion

49.	A person is standing on a truck moving with a constant velocity of 14.7 m/s on a horizontal road. The man throws a ball v that it returns to the truck after the truck has moved 58.8 m. Find the speed and the angle of projection (a) as seen from the truck, (b) as seen from the road.
Answer» A person is standing on a truck moving with a constant velocity of $14.7 m / s$ on a horizontal road. The man throws a ball $v$ that it returns to the truck after the truck has moved $58.8 m$ . Find the speed and the angle of projection (a) as seen from the truck, (b) as seen from the road.

Discussion

50.	A body of mass 15 kg revolves in a circle of diameter 1.20m, making 100 revolution per minute. Then, the linear velocity of body is:
Answer» A body of mass 15 kg revolves in a circle of diameter 1.20m, making 100 revolution per minute. Then, the linear velocity of body is:

Discussion

Explore topic-wise InterviewSolutions in Current Affairs.

∫ex(x−1)(x−ln x)x2dx is equal to

Why does resistivity and temperature varies- 1.directly to metals 2.inversely to semiconductors 3.doesnot varies with temperature in alloys ||Explain all three conditions in details.||

A biconvex lens of a focal length of 10 cm is to be made from a glass material. If the refractive index of the material is 1.5, what must be the radius of curvature of the surface of the lens? a) 0.1 m b) 0.15 m c) 0.20 m d) 0.30 m

A hollow sphere of radius R lies on a smooth horizontal surface. It is pulled by a horizontal force acting tangentially from the highest point. Find the distance travelled by the sphere during the time it makes one full rotation.

An automobile moves on a road with a speed of 54 km/hr. The radius of its wheels is 0.45 m and the moment of inertia of the wheel about its axis of rotation is 3 kg-m2. If the vehicle is brought to rest in 15 s, the magnitude of average torque transmitted by its brakes to the wheel is

A fan is rotating with angular velocity 100 rev/sec. Then, it is switched off. It takes 5 minutes to stop. Find the average angular velocity during this interval. (correct answer + 1, wrong answer - 0.25)

Angle of minimum deviation for a prism of refractive index 1.5 is equal to the angle of prism. The angle of prism is (cos41∘=0.75)

The resistivity vs. Temperature variation of a certain material is shown below. At 2∘C, this material will act as?

A particle of mass m is attached to three springs A, B and C of equal force constants k as shown in figure (12-E6). If the particle is pushed slightly against the spring C and released, find the time period of oscillation.

Which of the following principles are involved in the design of the Van de Graaf generator?

Water failing from a 50 m high fall is to be used for generating electric energy. If 1.8 ×105 Kg of water falls per hour and half the gravitational potential energy can be converted into electric energy, how many 100 W lamps can be lit?Take g=10 m/s2

Three concentric spheres are shown in figure. Find the potential on surface of shell B. Charge on A, B and C are 3Q,−2Q and Q respectively.

With what speed should a body be thrown upwards so that the distance traversed in 5th second and 6th second are equal? (Take g=9.8 m/s2)

How the graphical representation of spring force come ?

Four short dipoles each of dipole moment p are placed at the vertices of a square of side a. The direction of the dipole moments are shown in the figure.

A circular portion of radius R/2 is cut from a uniform circular disc of mass M and radius R as shown in the figure. Find the moment of inertia of the remaining body about an axis which is perpendicular to the plane of the disc and touches a point on the circumference of the disc as shown.

The resistance between points M and N in the circuit is

A pulse as shown in figure is moving fowards negative x - axis at v = 1 cm/s in a stretched string. End at (0, 0) is open. And given snapshot is at t = 0 sec at t = 3 sec. y - coordinate of string at x = 0.5 cm is cm.

An object of specific gravity ρ is hung from a thin steel wire. The fundamental frequency (in Hz) is 300Hz. The object is immersed in water with specific gravity ρw, so that one half its volume is submerged. The new fundamental frequency (in Hz) is

A uniform slender rod of length L, cross section area A and Young's modulus Y is acted upon by forces as shown in figure. If elongation of rod is nFLAY, then n is (Write upto two digits after the decimal point.)

The photosensitive metal is first irradiated with the radiation of wavelength 400 mm and then with radiation of wavelength 800 nm. The change in the maximum kinetic energy of the photoelectron assuming that both wavelengths can cause photoelectric emission, is

A ball is thrown vertically upward with a velocity of 10 m/s from the top of a tower of height of 50 m. Find the time taken by the ball to reach a height 10 m from the ground. (Take g=10 m/s2)

A capacitor of capacitance C0 is charged to a potential V0 and then isolated. A small capacitor C is then charged from C0, discharged and charged again; the process being repeated n times. Due to this, potential of the larger capacitor is decreased to V. The value of C is

When the ratio of the minimum velocity to the maximum velocity is 12 in a projectile motion, the angle of projection of projectile is?

Two bodies M and N of equal masses are suspended from two separate springs of the spring constant k1 and k2 respectively. If the two bodies oscillate vertically such that their maximum velocities are equal, the ratio of the amplitude of vibration of M to that on N is

A line makes angles 60o with Y-axis and 45o with Z-axis, the direction cosines of this line are:

How can we convert a galvanometer into an ammeter of given range?

A solid sphere of radius 5 cm floats in water. If a maximum load of 0.1 kg can be put on it without wetting the load, find the specific gravity of the material of the sphere.

Show that the speed of an electron in 1st Bohr orbit is c137, where c is the speed of light.

Mass M is divided into two parts m1and m2.fr a given separation the ratio of m1/M forwhich the gravitational attraction between the two parts becomes maximum is 1:1 1:2 1:3 1:4 Ans option 2 how?

what is the exact definition of dimension

Two stones A and B are projected simultaneously as shown in figure. It has been observed that both the stones reach the ground at the same place after 7 seconds of their projection. The difference in the vertical components of their initial velocities in m/s is (g=9.8 m/s2)

Two particles are executing simple harmonic motion of the same amplitude A and angular frequency ω along the x−axis. Their mean position is separated by distance Xo(Xo>A). If the maximum separation between them is (Xo+A), the phase difference between their motion is

Best physics reference books for JEE.

A gaseous mixture consists of 16 g He and 16 g O2. The ratio of specific heats CpCv of the mixture is

A person is standing on a truck moving with a constant velocity of 14.7 m/s on a horizontal road. The man throws a ball v that it returns to the truck after the truck has moved 58.8 m. Find the speed and the angle of projection (a) as seen from the truck, (b) as seen from the road.

A body of mass 15 kg revolves in a circle of diameter 1.20m, making 100 revolution per minute. Then, the linear velocity of body is:

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∫ex(x−1)(x−ln x)x2dx is equal to

Why does resistivity and temperature varies- 1.directly to metals 2.inversely to semiconductors 3.doesnot varies with temperature in alloys ||Explain all three conditions in details.||

A biconvex lens of a focal length of 10 cm is to be made from a glass material. If the refractive index of the material is 1.5, what must be the radius of curvature of the surface of the lens? a) 0.1 m b) 0.15 m c) 0.20 m d) 0.30 m

A hollow sphere of radius R lies on a smooth horizontal surface. It is pulled by a horizontal force acting tangentially from the highest point. Find the distance travelled by the sphere during the time it makes one full rotation.

An automobile moves on a road with a speed of 54 km/hr. The radius of its wheels is 0.45 m and the moment of inertia of the wheel about its axis of rotation is 3 kg-m2. If the vehicle is brought to rest in 15 s, the magnitude of average torque transmitted by its brakes to the wheel is

A fan is rotating with angular velocity 100 rev/sec. Then, it is switched off. It takes 5 minutes to stop. Find the average angular velocity during this interval. (correct answer + 1, wrong answer - 0.25)

Angle of minimum deviation for a prism of refractive index 1.5 is equal to the angle of prism. The angle of prism is (cos41∘=0.75)

The resistivity vs. Temperature variation of a certain material is shown below. At 2∘C, this material will act as?

A particle of mass m is attached to three springs A, B and C of equal force constants k as shown in figure (12-E6). If the particle is pushed slightly against the spring C and released, find the time period of oscillation.

Which of the following principles are involved in the design of the Van de Graaf generator?

Water failing from a 50 m high fall is to be used for generating electric energy. If 1.8 ×105 Kg of water falls per hour and half the gravitational potential energy can be converted into electric energy, how many 100 W lamps can be lit?Take g=10 m/s2

Three concentric spheres are shown in figure. Find the potential on surface of shell B. Charge on A, B and C are 3Q,−2Q and Q respectively.

With what speed should a body be thrown upwards so that the distance traversed in 5th second and 6th second are equal? (Take g=9.8 m/s2)

How the graphical representation of spring force come ?

Four short dipoles each of dipole moment p are placed at the vertices of a square of side a. The direction of the dipole moments are shown in the figure.

A circular portion of radius R/2 is cut from a uniform circular disc of mass M and radius R as shown in the figure. Find the moment of inertia of the remaining body about an axis which is perpendicular to the plane of the disc and touches a point on the circumference of the disc as shown.

The resistance between points M and N in the circuit is

A pulse as shown in figure is moving fowards negative x - axis at v = 1 cm/s in a stretched string. End at (0, 0) is open. And given snapshot is at t = 0 sec at t = 3 sec. y - coordinate of string at x = 0.5 cm is cm.

An object of specific gravity ρ is hung from a thin steel wire. The fundamental frequency (in Hz) is 300Hz. The object is immersed in water with specific gravity ρw, so that one half its volume is submerged. The new fundamental frequency (in Hz) is

A uniform slender rod of length L, cross section area A and Young's modulus Y is acted upon by forces as shown in figure. If elongation of rod is nFLAY, then n is (Write upto two digits after the decimal point.)

The photosensitive metal is first irradiated with the radiation of wavelength 400 mm and then with radiation of wavelength 800 nm. The change in the maximum kinetic energy of the photoelectron assuming that both wavelengths can cause photoelectric emission, is

A ball is thrown vertically upward with a velocity of 10 m/s from the top of a tower of height of 50 m. Find the time taken by the ball to reach a height 10 m from the ground. (Take g=10 m/s2)

A capacitor of capacitance C0 is charged to a potential V0 and then isolated. A small capacitor C is then charged from C0, discharged and charged again; the process being repeated n times. Due to this, potential of the larger capacitor is decreased to V. The value of C is

When the ratio of the minimum velocity to the maximum velocity is 12 in a projectile motion, the angle of projection of projectile is?

Two bodies M and N of equal masses are suspended from two separate springs of the spring constant k1 and k2 respectively. If the two bodies oscillate vertically such that their maximum velocities are equal, the ratio of the amplitude of vibration of M to that on N is

A line makes angles 60o with Y-axis and 45o with Z-axis, the direction cosines of this line are:

How can we convert a galvanometer into an ammeter of given range?

A solid sphere of radius 5 cm floats in water. If a maximum load of 0.1 kg can be put on it without wetting the load, find the specific gravity of the material of the sphere.

Show that the speed of an electron in 1st Bohr orbit is c137, where c is the speed of light.

Mass M is divided into two parts m1and m2.fr a given separation the ratio of m1/M forwhich the gravitational attraction between the two parts becomes maximum is 1:1 1:2 1:3 1:4 Ans option 2 how?

what is the exact definition of dimension

Two stones A and B are projected simultaneously as shown in figure. It has been observed that both the stones reach the ground at the same place after 7 seconds of their projection. The difference in the vertical components of their initial velocities in m/s is (g=9.8 m/s2)

Two particles are executing simple harmonic motion of the same amplitude A and angular frequency ω along the x−axis. Their mean position is separated by distance Xo(Xo&gt;A). If the maximum separation between them is (Xo+A), the phase difference between their motion is

Best physics reference books for JEE.

A gaseous mixture consists of 16 g He and 16 g O2. The ratio of specific heats CpCv of the mixture is

A person is standing on a truck moving with a constant velocity of 14.7 m/s on a horizontal road. The man throws a ball v that it returns to the truck after the truck has moved 58.8 m. Find the speed and the angle of projection (a) as seen from the truck, (b) as seen from the road.

A body of mass 15 kg revolves in a circle of diameter 1.20m, making 100 revolution per minute. Then, the linear velocity of body is:

Two particles are executing simple harmonic motion of the same amplitude A and angular frequency ω along the x−axis. Their mean position is separated by distance Xo(Xo>A). If the maximum separation between them is (Xo+A), the phase difference between their motion is