50278 + Interview Questions in Physics

1.	A stream of water flowing horizontally with a speed of 15 ms−1 gushes out of a tube of cross-sectional area 10−2 m2, and hits a vertical wall nearby. What is the force exerted on the wall by the impact of water, assuming it does not rebound?
Answer» A stream of water flowing horizontally with a speed of $15 m s^{- 1}$ gushes out of a tube of cross-sectional area $10^{- 2} m^{2}$ , and hits a vertical wall nearby. What is the force exerted on the wall by the impact of water, assuming it does not rebound?

Discussion

2.	A soccer ball is kicked from the ground with an initial speed of 20 m/s at an upward angle of 45∘. A player 55 m away in the direction of the kick starts running to meet the ball at that instant. What must be his average speed if he is to meet the ball just before it hits the ground?
Answer» A soccer ball is kicked from the ground with an initial speed of 20 m/s at an upward angle of $45^{\circ}$ . A player 55 m away in the direction of the kick starts running to meet the ball at that instant. What must be his average speed if he is to meet the ball just before it hits the ground?

Discussion

3.	Velocity of the river with respect to ground is given by v0. Width of the river is d. A swimmer swims (with respect to water) perpendicular to the current with acceleration a=2t (where t is time) starting from rest from the origin O at t=0. The equation of trajectory of the path followed by the swimmer is
Answer» Velocity of the river with respect to ground is given by $v_{0}$ . Width of the river is $d$ . A swimmer swims (with respect to water) perpendicular to the current with acceleration $a = 2 t$ (where $t$ is time) starting from rest from the origin $O$ at $t = 0$ . The equation of trajectory of the path followed by the swimmer is

Discussion

4.	What is the difference between delta H and delta Q? In deriving the ΔG=ΔH-TΔS, why have we considered them different .
Answer» What is the difference between delta H and delta Q? In deriving the ΔG=ΔH-TΔS, why have we considered them different .

Discussion

5.	A stone is projected from a horizontal plane. It attains maximum height ′H′ & strikes a stationary smooth wall & falls on the ground vertically below the maximum height. Assume the collision to be elastic, the height of the point on the wall where ball will strike is (Elastic collision means that after colliding on a plane the perpendicular component of the velocity before collision gets reversed after the collision. Here vx is normal to plane)
Answer» A stone is projected from a horizontal plane. It attains maximum height $^{'} H^{'}$ & strikes a stationary smooth wall & falls on the ground vertically below the maximum height. Assume the collision to be elastic, the height of the point on the wall where ball will strike is (Elastic collision means that after colliding on a plane the perpendicular component of the velocity before collision gets reversed after the collision. Here $v_{x}$ is normal to plane)

5.

A stone is projected from a horizontal plane. It attains maximum height ′H′ & strikes a stationary smooth wall & falls on the ground vertically below the maximum height. Assume the collision to be elastic, the height of the point on the wall where ball will strike is (Elastic collision means that after colliding on a plane the perpendicular component of the velocity before collision gets reversed after the collision. Here vx is normal to plane)

Answer»

A stone is projected from a horizontal plane. It attains maximum height $^{'} H^{'}$ & strikes a stationary smooth wall & falls on the ground vertically below the maximum height. Assume the collision to be elastic, the height of the point on the wall where ball will strike is

(Elastic collision means that after colliding on a plane the perpendicular component of the velocity before collision gets reversed after the collision. Here $v_{x}$ is normal to plane)

Discussion

6.	coefficient of linear expansion of a crystal in 3 mutually perpendicular diretions are 0.0000085 ,0.0000105 ,0.000011 if the mass of the crystal is 25grams ,if the density at 0 degree c is 5grams find its volume
Answer» coefficient of linear expansion of a crystal in 3 mutually perpendicular diretions are 0.0000085 ,0.0000105 ,0.000011 if the mass of the crystal is 25grams ,if the density at 0 degree c is 5grams find its volume

Discussion

7.	An inductor of inductance L=5 H is connected to an AC source having voltage V=10 sin(10t). What is the value of peak current?
Answer» An inductor of inductance $L = 5 H$ is connected to an AC source having voltage $V = 10 sin (10 t)$ . What is the value of peak current?

Discussion

8.	What is means of zero vector? Explain with example?
Answer» What is means of zero vector? Explain with example?

Discussion

9.	An object (ABED) is placed in front of a concave mirror beyond the centre of curvature (C) as shown in the figure. The shape of image will be :
Answer» An object $(A B E D)$ is placed in front of a concave mirror beyond the centre of curvature $(C)$ as shown in the figure. The shape of image will be :

Discussion

10.	In the given figure, All surface are smooth & g=10 m/s2. The force F required to keep 4 kg in equilibria is (Write upto two digits after the decimal point)
Answer» In the given figure, All surface are smooth & $g = 10 m / s^{2}$ . The force F required to keep 4 kg in equilibria is (Write upto two digits after the decimal point)

Discussion

11.	Two blocks of mass m1=2 kg,m2=4 kg connected by weightless spring of stiffness k rest on a horizontal plane as shown. m2 is shifted a small distance x=1 cm to the left and then released. Find the velocity of COM of the system just after m1 break off the wall. Assume k=4 N/m.
Answer» Two blocks of mass $m_{1} = 2 kg, m_{2} = 4 kg$ connected by weightless spring of stiffness $k$ rest on a horizontal plane as shown. $m_{2}$ is shifted a small distance $x = 1 cm$ to the left and then released. Find the velocity of COM of the system just after $m_{1}$ break off the wall. Assume $k = 4 N/m$ .

Discussion

12.	Find the radius of gyration of a uniform disc of radius R and mass M about its edge and perpendicular to the disc.
Answer» Find the radius of gyration of a uniform disc of radius $R$ and mass $M$ about its edge and perpendicular to the disc.

Discussion

13.	A parallel-plate capacitor has a dielectric slab in it. The slab just fills the space inside the capacitor. The capacitor is charged by a battery and then the battery is disconnected. Now, the slab is pulled out slowly at t=0. If at time t, the capacitance of the capacitor is C and potential difference between the plates of the capacitor is V, then which of the following graphs is/are correct.
Answer» A parallel-plate capacitor has a dielectric slab in it. The slab just fills the space inside the capacitor. The capacitor is charged by a battery and then the battery is disconnected. Now, the slab is pulled out slowly at $t = 0$ . If at time $t$ , the capacitance of the capacitor is $C$ and potential difference between the plates of the capacitor is $V$ , then which of the following graphs is/are correct.

Discussion

14.	A uniform ball of radius r rolls without slipping down from the top of a sphere of radius R. The angular velocity of the ball when it breaks from the sphere is
Answer» A uniform ball of radius $r$ rolls without slipping down from the top of a sphere of radius $R$ . The angular velocity of the ball when it breaks from the sphere is

Discussion

15.	Electric charges +10μC,+5μC, and +8μC are placed at the corners of a square of side √2m. The potential at the centre of the square is
Answer» Electric charges $+ 10 μ C, + 5 μ C, a n d + 8 μ C$ are placed at the corners of a square of side $\sqrt{2} m$ . The potential at the centre of the square is

Discussion

16.	Rajat is sitting in an open cart that moves horizontally with an acceleration of 5 m/s2 rightwards. Rajat is unaware of his acceleration, and throws a ball up in the air. He attempts at drawing a Free Body Diagram of the ball assuming his frame to be inertial. Which of these would closely resemble his free body diagram of the ball (neglect air drag)?
Answer» Rajat is sitting in an open cart that moves horizontally with an acceleration of $5 m / s^{2}$ rightwards. Rajat is unaware of his acceleration, and throws a ball up in the air. He attempts at drawing a Free Body Diagram of the ball assuming his frame to be inertial. Which of these would closely resemble his free body diagram of the ball (neglect air drag)?

Discussion

17.	Vector →A having magnitude 5 N makes an angle 53∘ North of East, →B makes 37∘ North of West, magnitude of the resultant is 13 N. Find the magnitude of the vector →B.
Answer» Vector $\to A$ having magnitude $5 N$ makes an angle $53^{\circ}$ North of East, $\to B$ makes $37^{\circ}$ North of West, magnitude of the resultant is $13 N$ . Find the magnitude of the vector $\to B$ .

Discussion

18.	When is a transistor said to be in active state? Draw a circuit diagram of a p-n-p transistor and explain how it works as a transistor amplifier. Write clearly, why in the case of a transistor (i) the base is thin and lightly doped and (ii) the emitter is heavily doped.
Answer» When is a transistor said to be in active state? Draw a circuit diagram of a p-n-p transistor and explain how it works as a transistor amplifier. Write clearly, why in the case of a transistor (i) the base is thin and lightly doped and (ii) the emitter is heavily doped.

Discussion

19.	A ring of mass m and radius r is allowed to roll down without slipping on an inclined plane having inclination sin−1(110) from the horizontal. The magnitude of acceleration of it's centre of mass is
Answer» A ring of mass $m$ and radius $r$ is allowed to roll down without slipping on an inclined plane having inclination ${sin}^{- 1} (\frac{1}{10})$ from the horizontal. The magnitude of acceleration of it's centre of mass is

Discussion

20.	A balloon of mass M is descending at a constant acceleration a. When a mass m is released from the balloon, it starts rising with the same acceleration a. Assuming that its volume does not change, what is the value of m
Answer» A balloon of mass M is descending at a constant acceleration a. When a mass m is released from the balloon, it starts rising with the same acceleration a. Assuming that its volume does not change, what is the value of m

Discussion

21.	A string of length l fixed at both ends vibrates in resonance with a tuning fork of frequency 'f' at two successive values of tension T1 and T2 in the string. Find the specific mass (mass per unit length) of the string.
Answer» A string of length $l$ fixed at both ends vibrates in resonance with a tuning fork of frequency $' f'$ at two successive values of tension $T_{1}$ and $T_{2}$ in the string. Find the specific mass (mass per unit length) of the string.

Discussion

22.	A screw gauge gives the following reading for measuring the diameter of a wire. Main scale reading : 0 mm Circular scale reading : 60 divisions Given, that 1 mm on main scale corresponds to 100 divisions on circular scale. The diameter of wire is,
Answer» A screw gauge gives the following reading for measuring the diameter of a wire. Main scale reading : $0 mm$ Circular scale reading : $60$ divisions Given, that $1 mm$ on main scale corresponds to $100$ divisions on circular scale. The diameter of wire is,

Discussion

23.	What is the equivalent capacitance of the system of capacitors between A and B ?
Answer» What is the equivalent capacitance of the system of capacitors between A and B ?

23.

What is the equivalent capacitance of the system of capacitors between A and B ?

Answer»

What is the equivalent capacitance of the system of capacitors between A and B ?

Discussion

24.	A uniform solid sphere of mass m and radius r is released from a wedge of mass 2m as shown. ABC is hemispherical position of radius R. Impulse imparted to the system consisting wedge and sphere by the vertical wall w1w2 till the time sphere reaches at the bottom most position of spherical portion for the first time is m√10g(R−r)δ. Friction between wedge and horizontal surface is absent and between sphere and wedge friction is sufficient to avoid slipping between them. Here δ is an integer. Find δ (Answer upto two digit after decimal places)
Answer» A uniform solid sphere of mass m and radius r is released from a wedge of mass 2m as shown. ABC is hemispherical position of radius R. Impulse imparted to the system consisting wedge and sphere by the vertical wall $w_{1} w_{2}$ till the time sphere reaches at the bottom most position of spherical portion for the first time is $m \sqrt{\frac{10 g (R - r)}{δ}}$ . Friction between wedge and horizontal surface is absent and between sphere and wedge friction is sufficient to avoid slipping between them. Here $δ$ is an integer. Find $δ$ (Answer upto two digit after decimal places)

Discussion

25.	A block of mass 2 kg is moving with speed v0 towards a massless unstreched spring (K=10N/m). It is found that for maximum speed v0=√6.4m/s, the block compresses the spring, stops at that position and does not return back. Friction coefficient at surface is μ=1x.Value of x is ___
Answer» A block of mass 2 kg is moving with speed $v_{0}$ towards a massless unstreched spring (K=10N/m). It is found that for maximum speed $v_{0} = \sqrt{6.4} m / s$ , the block compresses the spring, stops at that position and does not return back. Friction coefficient at surface is $μ = \frac{1}{x}$ .Value of x is ___

25.

A block of mass 2 kg is moving with speed v0 towards a massless unstreched spring (K=10N/m). It is found that for maximum speed v0=√6.4m/s, the block compresses the spring, stops at that position and does not return back. Friction coefficient at surface is μ=1x.Value of x is ___

Answer»

A block of mass 2 kg is moving with speed $v_{0}$ towards a massless unstreched spring (K=10N/m). It is found that for maximum speed $v_{0} = \sqrt{6.4} m / s$ , the block compresses the spring, stops at that position and does not return back. Friction coefficient at surface is $μ = \frac{1}{x}$ .Value of x is

___

Discussion

26.	A uniform rod of mass m and length L is hinged at one of its end with the ceiling and other end of the rod is attached with a thread which is attached with horizontal ceiling at point P. If one end of the rod is slightly displaced horizontally and perpendicular to the rod and released. If the time period of small oscillation is 2π√2l sin θxg Find x. ___
Answer» A uniform rod of mass m and length L is hinged at one of its end with the ceiling and other end of the rod is attached with a thread which is attached with horizontal ceiling at point P. If one end of the rod is slightly displaced horizontally and perpendicular to the rod and released. If the time period of small oscillation is $2 π \sqrt{\frac{2 l s i n θ}{x g}}$ Find x. ___

Discussion

27.	Why the direction of dipole is from negative to positive?
Answer» Why the direction of dipole is from negative to positive?

Discussion

28.	A small solid cylinder of mass M and radius R slides down a smooth curve from height h. It gets onto plank of mass M, which is resting on a smooth surface. If μ is coefficient of friction between cylinder and plank, the time at which that cylinder attains pure rolling on plank is found to be v0xμg where v0=√2gh. The value of 4x is (Assume plank has sufficient length for cylinder to attain pure rolling)
Answer» A small solid cylinder of mass $M$ and radius $R$ slides down a smooth curve from height $h$ . It gets onto plank of mass $M$ , which is resting on a smooth surface. If $μ$ is coefficient of friction between cylinder and plank, the time at which that cylinder attains pure rolling on plank is found to be $\frac{v_{0}}{x μ g}$ where $v_{0} = \sqrt{2 g h}$ . The value of $4 x$ is (Assume plank has sufficient length for cylinder to attain pure rolling)

Discussion

29.	A thin uniform annular disc (see figure) of mass M has outer radius 4R and inner radius 3R. If the work required to take a unit mass from point P on its axis to infinity is 2GMnR(4√2−5), then n = (n is an integer)
Answer» A thin uniform annular disc (see figure) of mass $M$ has outer radius $4 R$ and inner radius $3 R$ . If the work required to take a unit mass from point P on its axis to infinity is $\frac{2 G M}{n R} (4 \sqrt{2} - 5)$ , then $n$ = ( $n$ is an integer)

Discussion

30.	The force F acting on a particle moving in a straight line is shown in the figure below. Find the work done by the force from x = 0 to x = 1 m.
Answer» The force F acting on a particle moving in a straight line is shown in the figure below. Find the work done by the force from x = 0 to x = 1 m.

Discussion

31.	If a cylinder containing a gas at high pressure explodes, the gas undergoes
Answer» If a cylinder containing a gas at high pressure explodes, the gas undergoes

Discussion

32.	Two spheres P and Q, of same colour having radii 8 cm and 2 cm are maintained at temperatures 127o C and 527o C respectively. The ratio of energy radiated by P and Q is
Answer» Two spheres P and Q, of same colour having radii 8 cm and 2 cm are maintained at temperatures $127^{o} C$ and $527^{o} C$ respectively. The ratio of energy radiated by P and Q is

Discussion

33.	Why electrostatic field lines never cross each other?
Answer» Why electrostatic field lines never cross each other?

Discussion

34.	Two whistles A and B produces notes of frequencies 660 Hz and 596 Hz respectively. There is a listener at the mid-point of the line joining them. Now the whistle B and the listener start moving with speed 30 m/s away from the whistle A. If speed of sound be 330 m/s, how many beats will be heard by the listener
Answer» Two whistles A and B produces notes of frequencies 660 Hz and 596 Hz respectively. There is a listener at the mid-point of the line joining them. Now the whistle B and the listener start moving with speed 30 m/s away from the whistle A. If speed of sound be 330 m/s, how many beats will be heard by the listener

Discussion

35.	A scooter is going round a circular road of radius 100 m at a speed of 10 m/s. The angular speed of the scooter will be
Answer» A scooter is going round a circular road of radius 100 m at a speed of 10 m/s. The angular speed of the scooter will be

Discussion

36.	A bullet of mass 50 gm is fired from a gun towards a ball of mass 450 gm The bullet hits the ball with speed 200 m/s in horizontal direction as shown in figure, and remains inside it. Find the magnitude of velocity of system of (ball+ bullet) after collision.
Answer» A bullet of mass $50 gm$ is fired from a gun towards a ball of mass $450 gm$ The bullet hits the ball with speed $200 m/s$ in horizontal direction as shown in figure, and remains inside it. Find the magnitude of velocity of system of (ball+ bullet) after collision.

Discussion

37.	A smooth sphere of radius R is made to translate in a straight line with a constant acceleration of 'a' . A particle kept on the top of the sphere is released from there at zero velocity with respect to the sphere.Find the speed of the particle with respect to the sphere as a function of the angle ø it slides.
Answer» A smooth sphere of radius R is made to translate in a straight line with a constant acceleration of 'a' . A particle kept on the top of the sphere is released from there at zero velocity with respect to the sphere.Find the speed of the particle with respect to the sphere as a function of the angle ø it slides.

Discussion

38.	In electrolytic cell flow of electron is from : a)cathod to anode in solution b)cathode to anode through external supply c)cathode to anode through internal supply d)anode to cathode to internal supply [Doubt: what is internal and external supply here ,Pls explain Concept and answer]
Answer» In electrolytic cell flow of electron is from : a)cathod to anode in solution b)cathode to anode through external supply c)cathode to anode through internal supply d)anode to cathode to internal supply [Doubt: what is internal and external supply here ,Pls explain Concept and answer]

38.

In electrolytic cell flow of electron is from : a)cathod to anode in solution b)cathode to anode through external supply c)cathode to anode through internal supply d)anode to cathode to internal supply [Doubt: what is internal and external supply here ,Pls explain Concept and answer]

Answer»

In electrolytic cell flow of electron is from :
a)cathod to anode in solution
b)cathode to anode through external supply
c)cathode to anode through internal supply
d)anode to cathode to internal supply

[Doubt: what is internal and external supply here ,Pls explain Concept and answer]

Discussion

39.	What is value of time period of geo stationary satellite in its orbit around the earth?
Answer» What is value of time period of geo stationary satellite in its orbit around the earth?

Discussion

40.	A body starts from rest and is uniformly accelerated for 30 s. The distance travelled in the first 10 s is x1, next 10 s is x2 and the last 10 s is x3. Then x1:x2:x3 is the same as
Answer» A body starts from rest and is uniformly accelerated for $30 s$ . The distance travelled in the first $10 s$ is $x_{1}$ , next $10 s$ is $x_{2}$ and the last $10 s$ is $x_{3}$ . Then $x_{1} : x_{2} : x_{3}$ is the same as

Discussion

41.	A circular ring of mass 6 kg and radius a is placed such that its centre lies at the origin. Two particles of masses 2 kg each are placed at the intersecting points of the circle with +ve x-axis and +ve y -axis. Then, the angle made by the position vector of centre of mass of entire system with x - axis is
Answer» A circular ring of mass $6 kg$ and radius a is placed such that its centre lies at the origin. Two particles of masses $2 kg$ each are placed at the intersecting points of the circle with +ve x-axis and +ve y -axis. Then, the angle made by the position vector of centre of mass of entire system with x - axis is

Discussion

42.	A 5000 kg rocket is set for vertical firing. The exhaust speed is 800 m/s. To give an initial upward acceleration of 20 m/s2, the amount of gas ejected per second to supply the needed thrust will be (take g=10 m/s2)
Answer» A $5000 k g$ rocket is set for vertical firing. The exhaust speed is $800 m / s$ . To give an initial upward acceleration of $20 m / s^{2}$ , the amount of gas ejected per second to supply the needed thrust will be (take $g = 10 m / s^{2})$

Discussion

43.	The unit vector along ^i+^j is
Answer» The unit vector along $^i +^j$ is

Discussion

44.	Energy required to remove an electron from aluminium surface is 4.2 eV. If light of wavelength 2000∘A falls on the surface, the velocity of the fastest electron ejected from the surface will be
Answer» Energy required to remove an electron from aluminium surface is 4.2 eV. If light of wavelength $2000 \circ A$ falls on the surface, the velocity of the fastest electron ejected from the surface will be

Discussion

45.	A car is travelling on a straight road. The maximum velocity the car can attain is 24 m/s. The maximum acceleration and deceleration it can attain are 1 ms−2 and 4 ms−2 respectively. The shortest time( in s) the car takes from rest to rest in a distance of 480m is:
Answer» A car is travelling on a straight road. The maximum velocity the car can attain is $24 m/s$ . The maximum acceleration and deceleration it can attain are $1 {ms}^{- 2} and 4 {ms}^{- 2}$ respectively. The shortest time( in $s$ ) the car takes from rest to rest in a distance of $480 m$ is:

Discussion

46.	Age of fossils was previously determined by radioactive elements. More precise recent method which has led to revision of evolutionary period is
Answer» Age of fossils was previously determined by radioactive elements. More precise recent method which has led to revision of evolutionary period is

Discussion

47.	Locate the image formed by refraction in the situation shown in figure.
Answer» Locate the image formed by refraction in the situation shown in figure.

47.

Locate the image formed by refraction in the situation shown in figure.

Answer»

Locate the image formed by refraction in the situation shown in figure.

Discussion

48.	What is commutator
Answer» What is commutator

Discussion

49.	We cannot move a finger without disturbing all the stars. Explain.
Answer» We cannot move a finger without disturbing all the stars. Explain.

Discussion

50.	What is accuracy and precision? With examples. Why do we take averages when there are more than one experiment ?
Answer» What is accuracy and precision? With examples. Why do we take averages when there are more than one experiment ?

50.

What is accuracy and precision? With examples. Why do we take averages when there are more than one experiment ?

Answer»

What is accuracy and precision? With examples.

Why do we take averages when there are more than one experiment ?

Discussion

Explore topic-wise InterviewSolutions in Current Affairs.

A stream of water flowing horizontally with a speed of 15 ms−1 gushes out of a tube of cross-sectional area 10−2 m2, and hits a vertical wall nearby. What is the force exerted on the wall by the impact of water, assuming it does not rebound?

A soccer ball is kicked from the ground with an initial speed of 20 m/s at an upward angle of 45∘. A player 55 m away in the direction of the kick starts running to meet the ball at that instant. What must be his average speed if he is to meet the ball just before it hits the ground?

What is the difference between delta H and delta Q? In deriving the ΔG=ΔH-TΔS, why have we considered them different .

coefficient of linear expansion of a crystal in 3 mutually perpendicular diretions are 0.0000085 ,0.0000105 ,0.000011 if the mass of the crystal is 25grams ,if the density at 0 degree c is 5grams find its volume

An inductor of inductance L=5 H is connected to an AC source having voltage V=10 sin(10t). What is the value of peak current?

What is means of zero vector? Explain with example?

An object (ABED) is placed in front of a concave mirror beyond the centre of curvature (C) as shown in the figure. The shape of image will be :

In the given figure, All surface are smooth & g=10 m/s2. The force F required to keep 4 kg in equilibria is (Write upto two digits after the decimal point)

Two blocks of mass m1=2 kg,m2=4 kg connected by weightless spring of stiffness k rest on a horizontal plane as shown. m2 is shifted a small distance x=1 cm to the left and then released. Find the velocity of COM of the system just after m1 break off the wall. Assume k=4 N/m.

Find the radius of gyration of a uniform disc of radius R and mass M about its edge and perpendicular to the disc.

A uniform ball of radius r rolls without slipping down from the top of a sphere of radius R. The angular velocity of the ball when it breaks from the sphere is

Electric charges +10μC,+5μC, and +8μC are placed at the corners of a square of side √2m. The potential at the centre of the square is

Vector →A having magnitude 5 N makes an angle 53∘ North of East, →B makes 37∘ North of West, magnitude of the resultant is 13 N. Find the magnitude of the vector →B.

When is a transistor said to be in active state? Draw a circuit diagram of a p-n-p transistor and explain how it works as a transistor amplifier. Write clearly, why in the case of a transistor (i) the base is thin and lightly doped and (ii) the emitter is heavily doped.

A ring of mass m and radius r is allowed to roll down without slipping on an inclined plane having inclination sin−1(110) from the horizontal. The magnitude of acceleration of it's centre of mass is

A balloon of mass M is descending at a constant acceleration a. When a mass m is released from the balloon, it starts rising with the same acceleration a. Assuming that its volume does not change, what is the value of m

A string of length l fixed at both ends vibrates in resonance with a tuning fork of frequency 'f' at two successive values of tension T1 and T2 in the string. Find the specific mass (mass per unit length) of the string.

A screw gauge gives the following reading for measuring the diameter of a wire. Main scale reading : 0 mm Circular scale reading : 60 divisions Given, that 1 mm on main scale corresponds to 100 divisions on circular scale. The diameter of wire is,

What is the equivalent capacitance of the system of capacitors between A and B ?

A block of mass 2 kg is moving with speed v0 towards a massless unstreched spring (K=10N/m). It is found that for maximum speed v0=√6.4m/s, the block compresses the spring, stops at that position and does not return back. Friction coefficient at surface is μ=1x.Value of x is ___

Why the direction of dipole is from negative to positive?

A thin uniform annular disc (see figure) of mass M has outer radius 4R and inner radius 3R. If the work required to take a unit mass from point P on its axis to infinity is 2GMnR(4√2−5), then n = (n is an integer)

The force F acting on a particle moving in a straight line is shown in the figure below. Find the work done by the force from x = 0 to x = 1 m.

If a cylinder containing a gas at high pressure explodes, the gas undergoes

Two spheres P and Q, of same colour having radii 8 cm and 2 cm are maintained at temperatures 127o C and 527o C respectively. The ratio of energy radiated by P and Q is

Why electrostatic field lines never cross each other?

A scooter is going round a circular road of radius 100 m at a speed of 10 m/s. The angular speed of the scooter will be

A bullet of mass 50 gm is fired from a gun towards a ball of mass 450 gm The bullet hits the ball with speed 200 m/s in horizontal direction as shown in figure, and remains inside it. Find the magnitude of velocity of system of (ball+ bullet) after collision.

In electrolytic cell flow of electron is from : a)cathod to anode in solution b)cathode to anode through external supply c)cathode to anode through internal supply d)anode to cathode to internal supply [Doubt: what is internal and external supply here ,Pls explain Concept and answer]

What is value of time period of geo stationary satellite in its orbit around the earth?

A body starts from rest and is uniformly accelerated for 30 s. The distance travelled in the first 10 s is x1, next 10 s is x2 and the last 10 s is x3. Then x1:x2:x3 is the same as

A 5000 kg rocket is set for vertical firing. The exhaust speed is 800 m/s. To give an initial upward acceleration of 20 m/s2, the amount of gas ejected per second to supply the needed thrust will be (take g=10 m/s2)

The unit vector along ^i+^j is

Energy required to remove an electron from aluminium surface is 4.2 eV. If light of wavelength 2000∘A falls on the surface, the velocity of the fastest electron ejected from the surface will be

A car is travelling on a straight road. The maximum velocity the car can attain is 24 m/s. The maximum acceleration and deceleration it can attain are 1 ms−2 and 4 ms−2 respectively. The shortest time( in s) the car takes from rest to rest in a distance of 480m is:

Age of fossils was previously determined by radioactive elements. More precise recent method which has led to revision of evolutionary period is

Locate the image formed by refraction in the situation shown in figure.

What is commutator

We cannot move a finger without disturbing all the stars. Explain.

What is accuracy and precision? With examples. Why do we take averages when there are more than one experiment ?