50278 + Interview Questions in Physics

1.	The coordinates of a moving particle at any time 't' are given by x= ∝t3 and y=βt3. The speed of the particle at time 't' is
Answer» The coordinates of a moving particle at any time 't' are given by x= ∝t³ and y=βt³. The speed of the particle at time 't' is

1.

The coordinates of a moving particle at any time 't' are given by x= ∝t3 and y=βt3. The speed of the particle at time 't' is

Answer»

The coordinates of a moving particle at any time 't' are given by x= ∝t³ and y=βt³. The speed of the particle at time 't' is

Discussion

2.	A coil of resistance 400 Ω is placed in a magnetic field. If the magnetic flux ϕ (Wb) linked with the coil varies with time t(s) as ϕ=50t2+4. The induced current in the coil at t=2 s is
Answer» A coil of resistance $400$ $Ω$ is placed in a magnetic field. If the magnetic flux $ϕ (W b)$ linked with the coil varies with time $t (s)$ as $ϕ = 50 t^{2} + 4.$ The induced current in the coil at $t = 2 s$ is

Discussion

3.	The electric field in a region of space is given by →E=8x^i−4y^j−4z^k. So, equation of lines of force in the plane, z = 0 is
Answer» The electric field in a region of space is given by $\to E = 8 x^i - 4 y^j - 4 z^k$ . So, equation of lines of force in the plane, z = 0 is

Discussion

4.	A point moves rectilinearly with deceleration which depends on the velocity v of the particle as a=k√v, where k is a positive constant. At the initial moment the velocity of the point is equal to v0. What distance will it cover before it stops, and what time it will take to cover that distance? Mark this time from the given options.
Answer» A point moves rectilinearly with deceleration which depends on the velocity $v$ of the particle as $a = k \sqrt{v}$ , where $k$ is a positive constant. At the initial moment the velocity of the point is equal to $v_{0}$ . What distance will it cover before it stops, and what time it will take to cover that distance? Mark this time from the given options.

Discussion

5.	Let there be a spherically symmetric charge distribution with charge density varying as ρ(r)=ρ0(54−rR) upto r = R and ρ(r)=0 for r > R, where r is the distance from the origin. The electric field at a distance r(r < R) from the origin is given by:
Answer» Let there be a spherically symmetric charge distribution with charge density varying as $ρ (r) = ρ_{0} (\frac{5}{4} - \frac{r}{R})$ upto r = R and $ρ (r) = 0$ for r > R, where r is the distance from the origin. The electric field at a distance r(r < R) from the origin is given by:

Discussion

6.	Stoke's law states that the viscous drag force F experience by a sphere of radius a, moving with a speed v through a fluid with coefficient of viscosity η, is given by F =6πηav If this fluid is flowing through a cylindrical pipe of radius r, length l and a pressure difference of P across its two ends, then the volume of water V which flows through the pipe in time t can be written as Vt=k(Pl)aηbrc Where k is a dimensionless constant. Correct values of a, b and c are
Answer» Stoke's law states that the viscous drag force F experience by a sphere of radius a, moving with a speed v through a fluid with coefficient of viscosity $η$ , is given by F =6 $π$ $η$ av If this fluid is flowing through a cylindrical pipe of radius r, length l and a pressure difference of P across its two ends, then the volume of water V which flows through the pipe in time t can be written as $\frac{V}{t} = k {(\frac{P}{l})}^{a} η^{b} r^{c}$ Where k is a dimensionless constant. Correct values of a, b and c are

6.

Stoke's law states that the viscous drag force F experience by a sphere of radius a, moving with a speed v through a fluid with coefficient of viscosity η, is given by F =6πηav If this fluid is flowing through a cylindrical pipe of radius r, length l and a pressure difference of P across its two ends, then the volume of water V which flows through the pipe in time t can be written as Vt=k(Pl)aηbrc Where k is a dimensionless constant. Correct values of a, b and c are

Answer»

Stoke's law states that the viscous drag force F experience by a sphere of radius a, moving with a speed v through a fluid with coefficient of viscosity $η$ , is given by F =6 $π$ $η$ av If this fluid is flowing through a cylindrical pipe of radius r, length l and a pressure difference of P across its two ends, then the volume of water V which flows through the pipe in time t can be written as

$\frac{V}{t} = k {(\frac{P}{l})}^{a} η^{b} r^{c}$

Where k is a dimensionless constant. Correct values of a, b and c are

Discussion

7.	Figure here shows P and Q as two equally intense coherent sources emitting radiations of wavelength 20 m. The separation PQ is 5.0 m and phase of P is ahead of the phase of Q by 90∘. A, B and C are three distant points of observation equidistant from the mid-point of PQ. The intensity of radiations at A, B, C will bear the ratio
Answer» Figure here shows P and Q as two equally intense coherent sources emitting radiations of wavelength 20 m. The separation PQ is 5.0 m and phase of P is ahead of the phase of Q by $90^{\circ}$ . A, B and C are three distant points of observation equidistant from the mid-point of PQ. The intensity of radiations at A, B, C will bear the ratio

Discussion

8.	Two soap bubbles of different radii RA and RB(<RA) coalesces to form an interface of radii R. The correct relation of R with RA and RB is
Answer» Two soap bubbles of different radii $R_{A}$ and $R_{B} (< R_{A})$ coalesces to form an interface of radii $R$ . The correct relation of $R$ with $R_{A}$ and $R_{B}$ is

Discussion

9.	A block of mass 5.0 kg slides down from the top of an inclined plane of length 3 m. The first 1 m of the plane is smooth and the next 2 m is rough. The block is released from rest and again comes to rest at the bottom of the plane. If the plane is inclined at 30∘ with the horizontal, find the coefficient of friction on the rough portion.
Answer» A block of mass $5.0 kg$ slides down from the top of an inclined plane of length $3 m$ . The first $1 m$ of the plane is smooth and the next $2 m$ is rough. The block is released from rest and again comes to rest at the bottom of the plane. If the plane is inclined at $30^{\circ}$ with the horizontal, find the coefficient of friction on the rough portion.

Discussion

10.	If the molecular weight of two gases are M1 and M2, then at a given tempreture the ratio of their root mean square velocity v1 and v2 will be
Answer» If the molecular weight of two gases are $M_{1}$ and $M_{2}$ , then at a given tempreture the ratio of their root mean square velocity $v_{1}$ and $v_{2}$ will be

10.

If the molecular weight of two gases are M1 and M2, then at a given tempreture the ratio of their root mean square velocity v1 and v2 will be

Answer»

If the molecular weight of two gases are $M_{1}$ and $M_{2}$ , then at a given tempreture the ratio of their root mean square velocity $v_{1}$ and $v_{2}$ will be

Discussion

11.	A body travels for 15 sec starting from rest with constant acceleration. If it travels distances S1,S2 and S3 in the first five seconds, second five seconds and next five seconds respectively the relation between S1,S2 and S3 is
Answer» A body travels for $15 sec$ starting from rest with constant acceleration. If it travels distances $S_{1}, S_{2}$ and $S_{3}$ in the first five seconds, second five seconds and next five seconds respectively the relation between $S_{1}, S_{2}$ and $S_{3}$ is

Discussion

12.	A particle of mass m is subjected to a force →F=F0[cos(t)^i+sin(t)^j]. If initially (t = 0), the particle was at rest, then the kinetic energy of the particle at any time ‘t’ is given by
Answer» A particle of mass m is subjected to a force $\to F = F_{0} [c o s (t)^i + s i n (t)^j]$ . If initially (t = 0), the particle was at rest, then the kinetic energy of the particle at any time ‘t’ is given by

Discussion

13.	Is current a vector or a scalar quantity?
Answer» Is current a vector or a scalar quantity?

Discussion

14.	Consider two hot bodies B1 and B2 which have temperatures 100o C and 80o C respectively at t=0. The temperature of the surroundings is 40o C. The ratio of the respective rates of cooling R1 and R2 of these two bodies at t=0 will be
Answer» Consider two hot bodies $B_{1} a n d B_{2}$ which have temperatures $100^{o} C a n d 80^{o} C$ respectively at t=0. The temperature of the surroundings is $40^{o} C$ . The ratio of the respective rates of cooling $R_{1} a n d R_{2}$ of these two bodies at t=0 will be

Discussion

15.	If y=x3, then d2ydx2 is
Answer» If $y = x^{3}$ , then $\frac{d^{2} y}{d x^{2}}$ is

Discussion

16.	A 10 kg mass and a 0.5 kg mass hang at two ends of a string that passes over a smooth tube as shown in the figure. The 0.5 kg mass moves on a circular path in a horizontal plane about vertical axis. The length of string connecting the 0.5 kg mass to the top of the tube is 4 m and it makes 30∘ with the vertical. Then what should be the frequency of revolution (in cycles/sec) of 0.5 kg mass so that 10 kg mass remains stationary ?
Answer» A $10 kg$ mass and a $0.5 kg$ mass hang at two ends of a string that passes over a smooth tube as shown in the figure. The $0.5 kg$ mass moves on a circular path in a horizontal plane about vertical axis. The length of string connecting the $0.5 kg$ mass to the top of the tube is $4 m$ and it makes $30^{\circ}$ with the vertical. Then what should be the frequency of revolution (in $cycles/sec$ ) of $0.5 kg$ mass so that $10 kg$ mass remains stationary ?

Discussion

17.	Two small boats are 10 m apart on a lake. Each pops up and down with a period of 4.0 seconds due to wave motion on the surface of water. When one boat is at its highest point, the other boat is at its lowest point. Both boats are always within a single cycle of the waves. The speed of the waves is (in m/s)
Answer» Two small boats are $10 m$ apart on a lake. Each pops up and down with a period of $4.0 seconds$ due to wave motion on the surface of water. When one boat is at its highest point, the other boat is at its lowest point. Both boats are always within a single cycle of the waves. The speed of the waves is (in m/s)

Discussion

18.	Equal masses of two liquids having densities d1 and d2 are mixed together. The density of the resulting mixture is
Answer» Equal masses of two liquids having densities $d_{1}$ and $d_{2}$ are mixed together. The density of the resulting mixture is

Discussion

19.	Match the block diagrams of block of mass (m) with their corresponding free body diagram (every surface is frictionless) (bodies are at rest with respect to ground)
Answer» Match the block diagrams of block of mass (m) with their corresponding free body diagram (every surface is frictionless) (bodies are at rest with respect to ground)

19.

Match the block diagrams of block of mass (m) with their corresponding free body diagram (every surface is frictionless) (bodies are at rest with respect to ground)

Answer»

Match the block diagrams of block of mass (m) with their corresponding free body diagram (every surface is frictionless)

(bodies are at rest with respect to ground)

Discussion

20.	A boy throws n balls per second at regular time intervals. When the first ball reaches the maximum height he throws the second one vertically up. Find the maximum height reached by each ball.
Answer» A boy throws n balls per second at regular time intervals. When the first ball reaches the maximum height he throws the second one vertically up. Find the maximum height reached by each ball.

Discussion

21.	Calculate the effective resistance across A and K.
Answer» Calculate the effective resistance across A and K.

Discussion

22.	An object moves along a straight line with an acceleration of 2 m/s2. If its initial speed is 10 m/s, what will be its speed 4 s later?
Answer» An object moves along a straight line with an acceleration of $2 {m/s}^{2}$ . If its initial speed is $10 m/s$ , what will be its speed $4 s$ later?

Discussion

23.	The acceleration of a particle in S.H.M. is [MP PMT 1993]
Answer» The acceleration of a particle in S.H.M. is [MP PMT 1993]

23.

The acceleration of a particle in S.H.M. is [MP PMT 1993]

Answer»

The acceleration of a particle in S.H.M. is

[MP PMT 1993]

Discussion

24.	The gravitational potential (V) and gravitational field (E) are plotted against distance r from the centre of a uniform spherical shell .Consider the following statement A)the plot of V against r is discontinuous B)the plot of E against r is discontinuous Which statement is correct or wrong and why?
Answer» The gravitational potential (V) and gravitational field (E) are plotted against distance r from the centre of a uniform spherical shell .Consider the following statement A)the plot of V against r is discontinuous B)the plot of E against r is discontinuous Which statement is correct or wrong and why?

24.

The gravitational potential (V) and gravitational field (E) are plotted against distance r from the centre of a uniform spherical shell .Consider the following statement A)the plot of V against r is discontinuous B)the plot of E against r is discontinuous Which statement is correct or wrong and why?

Answer»

The gravitational potential (V) and gravitational field (E) are plotted against distance r from the centre of a uniform spherical shell .Consider the following statement

A)the plot of V against r is discontinuous

B)the plot of E against r is discontinuous

Which statement is correct or wrong and why?

Discussion

25.	Two identical square rods of metal are welded end to end as shown in figure (i), 20 calories of heat flows through it in 4 minutes. If the rods are welded as shown in figure (ii), the same amount of heat will flow through the rods in
Answer» Two identical square rods of metal are welded end to end as shown in figure (i), 20 calories of heat flows through it in 4 minutes. If the rods are welded as shown in figure (ii), the same amount of heat will flow through the rods in

Discussion

26.	A body of mass 'm' and radius 'r' is released from rest along a smooth inclined plane of angle of inclination θ. The angular momentum of the body about the instantaneous point of contact after a time 't' from the instant of release is equal to? (assume the inclined to be of indefinite length)
Answer» A body of mass 'm' and radius 'r' is released from rest along a smooth inclined plane of angle of inclination $θ$ . The angular momentum of the body about the instantaneous point of contact after a time 't' from the instant of release is equal to? (assume the inclined to be of indefinite length)

26.

A body of mass 'm' and radius 'r' is released from rest along a smooth inclined plane of angle of inclination θ. The angular momentum of the body about the instantaneous point of contact after a time 't' from the instant of release is equal to? (assume the inclined to be of indefinite length)

Answer»

A body of mass 'm' and radius 'r' is released from rest along a smooth inclined plane of angle of inclination $θ$ . The angular momentum of the body about the instantaneous point of contact after a time 't' from the instant of release is equal to? (assume the inclined to be of indefinite length)

Discussion

27.	Passengers in a bus lean forward as bus suddenly stops. This is due to
Answer» Passengers in a bus lean forward as bus suddenly stops. This is due to

Discussion

28.	Radioactive material 'A' has decay constant '8λ' and material 'B' has decay constant 'λ'. Initially they have same number of nuclei. After what time, the ratio of number of nuclei of material 'B' to that 'A' will be 1e?
Answer» Radioactive material ' $A$ ' has decay constant ' $8 λ$ ' and material ' $B$ ' has decay constant ' $λ$ '. Initially they have same number of nuclei. After what time, the ratio of number of nuclei of material 'B' to that 'A' will be $\frac{1}{e}$ ?

Discussion

29.	In a car lift, compressed air exerts a force F1 on a small piston having a radius of 5.0 cm. This pressure is transmitted to the second piston of radius 10.0 cm. If the mass of the car to be lifted by the second piston is 1350 kg, calculate F1 [Take g=10 m/s2]
Answer» In a car lift, compressed air exerts a force $F_{1}$ on a small piston having a radius of $5.0 cm$ . This pressure is transmitted to the second piston of radius $10.0 cm$ . If the mass of the car to be lifted by the second piston is $1350 kg$ , calculate $F_{1}$ [Take $g = 10 {m/s}^{2}$ ]

Discussion

30.	A metal wire is stretched by a load. Then the fractional change in its volume ΔVV is proportional to
Answer» A metal wire is stretched by a load. Then the fractional change in its volume $\frac{Δ V}{V}$ is proportional to

Discussion

31.	A person P is 600 m away from the station when train is approaching station with 72 km/h, it blows a whistle of frequency 800 Hz when 800 m away from the station. Find the frequency heard by the person. Speed of sound =340 ms−1.
Answer» A person $P$ is $600 m$ away from the station when train is approaching station with $72 km/h$ , it blows a whistle of frequency $800 Hz$ when $800 m$ away from the station. Find the frequency heard by the person. Speed of sound $= 340 {ms}^{- 1}$ .

Discussion

32.	The displacement-time graph of two moving objects. A and B are shown in the figure given below. Which of the following is incorrect? (1) B is moving with constant velocity (2) A is moving with increasing speed (3) B is moving with non-zero constant acceleration (4) Acceleration of A may be constant
Answer» The displacement-time graph of two moving objects. A and B are shown in the figure given below. Which of the following is incorrect? (1) B is moving with constant velocity (2) A is moving with increasing speed (3) B is moving with non-zero constant acceleration (4) Acceleration of A may be constant

Discussion

33.	What is Weak Nuclear Force?
Answer» What is Weak Nuclear Force?

Discussion

34.	(a) Determine the value of phase difference between the current and the voltage in the given series LCR circuit. (b) Calculate the value of additional capacitor which may be joined suitably to the capacitor C that would make the power factor of the circuit unity.
Answer» (a) Determine the value of phase difference between the current and the voltage in the given series LCR circuit. (b) Calculate the value of additional capacitor which may be joined suitably to the capacitor C that would make the power factor of the circuit unity.

Discussion

35.	A train moves with a speed of 30 km per hour in first 15 minutes with another speed of 40 km per hour the next 15 minutes and then with a speed of 60 km per hour last 30 minutes calculate the average of train during the journey
Answer» A train moves with a speed of 30 km per hour in first 15 minutes with another speed of 40 km per hour the next 15 minutes and then with a speed of 60 km per hour last 30 minutes calculate the average of train during the journey

Discussion

36.	. The phase difference between the current through the resistance and voltage across the resistance in a series LCR circuit is
Answer» . The phase difference between the current through the resistance and voltage across the resistance in a series LCR circuit is

Discussion

37.	Find the angular velocity of a body rotating with an acceleration of 2rev/s2 as it completes the 5th revolution after the start.[Concepts of Physics] BOOK ANSWER - 4.47 rev/s MY SOLUTION In one revolution the distance covered is 2π, so, in 5 revolution the distance moved is 10π Angular Acceleration = 2rev/s Initial angular velocity = 0 Final angular velocity = ? So using equation, v2 = u2 + 2as = 0 + 2* 2*10π = 40π v = 11.2rev/sec Why my Answer is different? Where and what I am missing. NOTE : I can't write omega on my tablet also you understand it well that we can type only that which is given in keyboard.
Answer» Find the angular velocity of a body rotating with an acceleration of 2rev/s² as it completes the 5th revolution after the start.[Concepts of Physics] BOOK ANSWER - 4.47 rev/s MY SOLUTION In one revolution the distance covered is 2π, so, in 5 revolution the distance moved is 10π Angular Acceleration = 2rev/s Initial angular velocity = 0 Final angular velocity = ? So using equation, v²= u²+ 2as = 0 + 2* 2*10π = 40π v = 11.2rev/sec Why my Answer is different? Where and what I am missing. NOTE : I can't write omega on my tablet also you understand it well that we can type only that which is given in keyboard.

Discussion

38.	The current in a solenoid of 240 turns, having a length of 12 cm and a radius of 2 cm, changes at a rate of0.8As−1 Find the emf induced in it.
Answer» The current in a solenoid of 240 turns, having a length of 12 cm and a radius of 2 cm, changes at a rate of $0.8 A s^{- 1}$ Find the emf induced in it.

Discussion

39.	A block A of mass 7 kg is placed on a frictionless table. A thread tied to it passes over a frictionless pulley and carries a body B of mass 3 kg at the other end. The acceleration of the system is (given g=10 ms−2)
Answer» A block A of mass 7 kg is placed on a frictionless table. A thread tied to it passes over a frictionless pulley and carries a body B of mass 3 kg at the other end. The acceleration of the system is $(g i v e n g = 10 m s^{- 2})$

39.

A block A of mass 7 kg is placed on a frictionless table. A thread tied to it passes over a frictionless pulley and carries a body B of mass 3 kg at the other end. The acceleration of the system is (given g=10 ms−2)

Answer»

A block A of mass 7 kg is placed on a frictionless table. A thread tied to it passes over a frictionless pulley and carries a body B of mass 3 kg at the other end. The acceleration of the system is $(g i v e n g = 10 m s^{- 2})$

Discussion

40.	(a) Find the first excitation potential of He+ ion. (b) Find the ionization potential of Li++ ion.
Answer» (a) Find the first excitation potential of $H e^{+}$ ion. (b) Find the ionization potential of $L i^{+ +}$ ion.

40.

(a) Find the first excitation potential of He+ ion. (b) Find the ionization potential of Li++ ion.

Answer»

(a) Find the first excitation potential of $H e^{+}$ ion.

(b) Find the ionization potential of $L i^{+ +}$ ion.

Discussion

41.	Two shells have been fired from cannon A and B simultaneously at t=0 with velocity as shown in the figure. Find the time when both shells collide in air, given that horizontal distance between cannons is 30 m.
Answer» Two shells have been fired from cannon $A$ and $B$ simultaneously at $t = 0$ with velocity as shown in the figure. Find the time when both shells collide in air, given that horizontal distance between cannons is $30 m$ .

Discussion

42.	A steel ball of mass 1kg is moving with a velocity 1 m/s. Then its de-Broglie wavelength is equal to
Answer» A steel ball of mass 1kg is moving with a velocity 1 m/s. Then its de-Broglie wavelength is equal to

Discussion

43.	A long,straight wire carries a current i.Let B1 be the magnetic field at a point P at a distance d from the wire.Consider a section of length l of this wire such that the point P lies on perpendicular bisector of the section.Let B2 be the magnetic field at this point due to this section only.Find the value of d/l so that B2 differs from B1 by 1%.
Answer» A long,straight wire carries a current i.Let $B_{1}$ be the magnetic field at a point P at a distance d from the wire.Consider a section of length l of this wire such that the point P lies on perpendicular bisector of the section.Let $B_{2}$ be the magnetic field at this point due to this section only.Find the value of d/l so that $B_{2}$ differs from $B_{1}$ by 1%.

Discussion

44.	Two ships are 10√2 km apart on a line joining south to north. The one further north is moving west with a speed of 25km/h while the other towards north with a speed of 25 km/h . What is their distance of closest approach and how long do they take to reach it?
Answer» Two ships are 10√2 km apart on a line joining south to north. The one further north is moving west with a speed of 25km/h while the other towards north with a speed of 25 km/h . What is their distance of closest approach and how long do they take to reach it?

Discussion

45.	Why pressure is generally called tensor quantity?
Answer» Why pressure is generally called tensor quantity?

Discussion

46.	Two particles A and B are moving in XY plane. Their positions vary with time t, according to relation xA(t)=4t2,xB(t)=7 yA(t)=3t,yB(t)=3+4t2 Distance between these two particles at t=1 s is:-
Answer» Two particles A and B are moving in XY plane. Their positions vary with time $t$ , according to relation $x_{A} (t) = 4 t^{2}, x_{B} (t) = 7$ $y_{A} (t) = 3 t, y_{B} (t) = 3 + 4 t^{2}$ Distance between these two particles at $t = 1 s$ is:-

Discussion

47.	Obtain expression for effective emf and internal resistance when two different cell connect parallel
Answer» Obtain expression for effective emf and internal resistance when two different cell connect parallel

Discussion

48.	If the displacement of a particle is given by at (square) what is dependency of acceleration on time
Answer» If the displacement of a particle is given by at (square) what is dependency of acceleration on time

Discussion

49.	A bullet emerges from a gun barrel of length 1.2 m with a speed of 640 m/s. Assuming constant acceleration, the approximate time that it spends in the barrel after the gun is fired is
Answer» A bullet emerges from a gun barrel of length $1.2 m$ with a speed of $640 m / s$ . Assuming constant acceleration, the approximate time that it spends in the barrel after the gun is fired is

Discussion

50.	Two identical balls A and B of equal masses, are lying on a smooth surface as shown in figure. Ball A hits ball B [which is initially at rest] and sticks to it. What should the minimum velocity of ball A, so that both balls reach the highest point of inclined place? Ignore the impact at the corner of the inclined surface.
Answer» Two identical balls $A$ and $B$ of equal masses, are lying on a smooth surface as shown in figure. Ball $A$ hits ball $B$ [which is initially at rest] and sticks to it. What should the minimum velocity of ball $A$ , so that both balls reach the highest point of inclined place? Ignore the impact at the corner of the inclined surface.

Discussion

Explore topic-wise InterviewSolutions in Current Affairs.

The coordinates of a moving particle at any time 't' are given by x= ∝t3 and y=βt3. The speed of the particle at time 't' is

A coil of resistance 400 Ω is placed in a magnetic field. If the magnetic flux ϕ (Wb) linked with the coil varies with time t(s) as ϕ=50t2+4. The induced current in the coil at t=2 s is

The electric field in a region of space is given by →E=8x^i−4y^j−4z^k. So, equation of lines of force in the plane, z = 0 is

Let there be a spherically symmetric charge distribution with charge density varying as ρ(r)=ρ0(54−rR) upto r = R and ρ(r)=0 for r &gt; R, where r is the distance from the origin. The electric field at a distance r(r &lt; R) from the origin is given by:

Two soap bubbles of different radii RA and RB(&lt;RA) coalesces to form an interface of radii R. The correct relation of R with RA and RB is

If the molecular weight of two gases are M1 and M2, then at a given tempreture the ratio of their root mean square velocity v1 and v2 will be

A body travels for 15 sec starting from rest with constant acceleration. If it travels distances S1,S2 and S3 in the first five seconds, second five seconds and next five seconds respectively the relation between S1,S2 and S3 is

A particle of mass m is subjected to a force →F=F0[cos(t)^i+sin(t)^j]. If initially (t = 0), the particle was at rest, then the kinetic energy of the particle at any time ‘t’ is given by

Is current a vector or a scalar quantity?

Consider two hot bodies B1 and B2 which have temperatures 100o C and 80o C respectively at t=0. The temperature of the surroundings is 40o C. The ratio of the respective rates of cooling R1 and R2 of these two bodies at t=0 will be

If y=x3, then d2ydx2 is

Equal masses of two liquids having densities d1 and d2 are mixed together. The density of the resulting mixture is

Match the block diagrams of block of mass (m) with their corresponding free body diagram (every surface is frictionless) (bodies are at rest with respect to ground)

A boy throws n balls per second at regular time intervals. When the first ball reaches the maximum height he throws the second one vertically up. Find the maximum height reached by each ball.

Calculate the effective resistance across A and K.

An object moves along a straight line with an acceleration of 2 m/s2. If its initial speed is 10 m/s, what will be its speed 4 s later?

The acceleration of a particle in S.H.M. is [MP PMT 1993]

Two identical square rods of metal are welded end to end as shown in figure (i), 20 calories of heat flows through it in 4 minutes. If the rods are welded as shown in figure (ii), the same amount of heat will flow through the rods in

A body of mass 'm' and radius 'r' is released from rest along a smooth inclined plane of angle of inclination θ. The angular momentum of the body about the instantaneous point of contact after a time 't' from the instant of release is equal to? (assume the inclined to be of indefinite length)

Passengers in a bus lean forward as bus suddenly stops. This is due to

Radioactive material 'A' has decay constant '8λ' and material 'B' has decay constant 'λ'. Initially they have same number of nuclei. After what time, the ratio of number of nuclei of material 'B' to that 'A' will be 1e?

In a car lift, compressed air exerts a force F1 on a small piston having a radius of 5.0 cm. This pressure is transmitted to the second piston of radius 10.0 cm. If the mass of the car to be lifted by the second piston is 1350 kg, calculate F1 [Take g=10 m/s2]

A metal wire is stretched by a load. Then the fractional change in its volume ΔVV is proportional to

A person P is 600 m away from the station when train is approaching station with 72 km/h, it blows a whistle of frequency 800 Hz when 800 m away from the station. Find the frequency heard by the person. Speed of sound =340 ms−1.

The displacement-time graph of two moving objects. A and B are shown in the figure given below. Which of the following is incorrect? (1) B is moving with constant velocity (2) A is moving with increasing speed (3) B is moving with non-zero constant acceleration (4) Acceleration of A may be constant

What is Weak Nuclear Force?

(a) Determine the value of phase difference between the current and the voltage in the given series LCR circuit. (b) Calculate the value of additional capacitor which may be joined suitably to the capacitor C that would make the power factor of the circuit unity.

A train moves with a speed of 30 km per hour in first 15 minutes with another speed of 40 km per hour the next 15 minutes and then with a speed of 60 km per hour last 30 minutes calculate the average of train during the journey

. The phase difference between the current through the resistance and voltage across the resistance in a series LCR circuit is

The current in a solenoid of 240 turns, having a length of 12 cm and a radius of 2 cm, changes at a rate of0.8As−1 Find the emf induced in it.

A block A of mass 7 kg is placed on a frictionless table. A thread tied to it passes over a frictionless pulley and carries a body B of mass 3 kg at the other end. The acceleration of the system is (given g=10 ms−2)

(a) Find the first excitation potential of He+ ion. (b) Find the ionization potential of Li++ ion.

Two shells have been fired from cannon A and B simultaneously at t=0 with velocity as shown in the figure. Find the time when both shells collide in air, given that horizontal distance between cannons is 30 m.

A steel ball of mass 1kg is moving with a velocity 1 m/s. Then its de-Broglie wavelength is equal to

Two ships are 10√2 km apart on a line joining south to north. The one further north is moving west with a speed of 25km/h while the other towards north with a speed of 25 km/h . What is their distance of closest approach and how long do they take to reach it?

Why pressure is generally called tensor quantity?

Two particles A and B are moving in XY plane. Their positions vary with time t, according to relation xA(t)=4t2,xB(t)=7 yA(t)=3t,yB(t)=3+4t2 Distance between these two particles at t=1 s is:-

Obtain expression for effective emf and internal resistance when two different cell connect parallel

If the displacement of a particle is given by at (square) what is dependency of acceleration on time

A bullet emerges from a gun barrel of length 1.2 m with a speed of 640 m/s. Assuming constant acceleration, the approximate time that it spends in the barrel after the gun is fired is

Let there be a spherically symmetric charge distribution with charge density varying as ρ(r)=ρ0(54−rR) upto r = R and ρ(r)=0 for r > R, where r is the distance from the origin. The electric field at a distance r(r < R) from the origin is given by:

Two soap bubbles of different radii RA and RB(<RA) coalesces to form an interface of radii R. The correct relation of R with RA and RB is