50278 + Interview Questions in Physics

1.	A block of mass m starts sliding on the plank of mass M. There is a sufficient friction between plank and the block. After some time both block and plank moves together. Choose the correct statement
Answer» A block of mass $m$ starts sliding on the plank of mass $M$ . There is a sufficient friction between plank and the block. After some time both block and plank moves together. Choose the correct statement

1.

A block of mass m starts sliding on the plank of mass M. There is a sufficient friction between plank and the block. After some time both block and plank moves together. Choose the correct statement

Answer»

A block of mass $m$ starts sliding on the plank of mass $M$ . There is a sufficient friction between plank and the block. After some time both block and plank moves together. Choose the correct statement

Discussion

2.	A concave mirror is placed at the bottom of an empty tank with face upwards and axis vertical. When sunlight falls normally on the mirror, it is focussed at distance of 32 cm from the mirror. If the tank filled with water (μ=43) upto a height of 20 cm, then the sunlight will now get focussed at
Answer» A concave mirror is placed at the bottom of an empty tank with face upwards and axis vertical. When sunlight falls normally on the mirror, it is focussed at distance of 32 cm from the mirror. If the tank filled with water $(μ = \frac{4}{3})$ upto a height of 20 cm, then the sunlight will now get focussed at

Discussion

3.	A block A of mass m1 rests on a horizontal table. A lights string connected to it passes over a frictionless pulley at the edge of table and from its other end another block B of mass m2 is suspended. The coefficient of kinetic friction between the block and the table is . When the block A is sliding on the table, the tension in the string is :
Answer» A block A of mass m₁ rests on a horizontal table. A lights string connected to it passes over a frictionless pulley at the edge of table and from its other end another block B of mass m₂ is suspended. The coefficient of kinetic friction between the block and the table is . When the block A is sliding on the table, the tension in the string is :

3.

A block A of mass m1 rests on a horizontal table. A lights string connected to it passes over a frictionless pulley at the edge of table and from its other end another block B of mass m2 is suspended. The coefficient of kinetic friction between the block and the table is . When the block A is sliding on the table, the tension in the string is :

Answer»

A block A of mass m₁ rests on a horizontal table. A lights string connected to it passes over a frictionless pulley at the edge of table and from its other end another block B of mass m₂ is suspended. The coefficient of kinetic friction between the block and the table is . When the block A is sliding on the table, the tension in the string is :

Discussion

4.	The focal lengths of a convex lens for red, yellow and violet rays are 100 cm, 98 cm and 96 cm respectively. Find the dispersive power of the material of the lens.
Answer» The focal lengths of a convex lens for red, yellow and violet rays are 100 cm, 98 cm and 96 cm respectively. Find the dispersive power of the material of the lens.

Discussion

5.	Two discs of mass 2 kg and 3 kg of radius 1 m and 2 m respectively placed together are rotated about an axis through their common centre as shown in figure. Find the net moment of inertia of the system about given axis.
Answer» Two discs of mass $2 kg$ and $3 kg$ of radius $1 m$ and $2 m$ respectively placed together are rotated about an axis through their common centre as shown in figure. Find the net moment of inertia of the system about given axis.

Discussion

6.	A charged particle is whirled anticlockwise in a horizontal circle on a frictionless table by attaching it to a string fixed at one point. What will happen to the tension in the string, if a magnetic field is switched on in the vertical direction?
Answer» A charged particle is whirled anticlockwise in a horizontal circle on a frictionless table by attaching it to a string fixed at one point. What will happen to the tension in the string, if a magnetic field is switched on in the vertical direction?

Discussion

7.	An inclined plane makes as angle θ0=30∘ with the horizontal. A particle is projected from this plane with a speed of 5 m/s at an angle of elevation β=30∘ with the horizontal as shown in the figure. Find the range of the particle on the plane when it strikes the plane. (Assume the incline is long enough and g=10 m/s2)
Answer» An inclined plane makes as angle $θ_{0} = 30^{\circ}$ with the horizontal. A particle is projected from this plane with a speed of $5 m/s$ at an angle of elevation $β = 30^{\circ}$ with the horizontal as shown in the figure. Find the range of the particle on the plane when it strikes the plane. (Assume the incline is long enough and $g = 10 {m/s}^{2}$ )

Discussion

8.	In the arrangement shown in figure, mA=4 kg and mB=1 kg. The system is released from rest and block B is found to have a speed of 0.3 m/s after it has descended through a distance of 1 m. Find the coefficient of friction between the block and the table. Neglect friction elsewhere. (Take g=10 m/s2).
Answer» In the arrangement shown in figure, $m_{A} = 4 kg$ and $m_{B} = 1 kg$ . The system is released from rest and block $B$ is found to have a speed of $0.3 m/s$ after it has descended through a distance of $1 m$ . Find the coefficient of friction between the block and the table. Neglect friction elsewhere. (Take $g = 10 {m/s}^{2}$ ).

Discussion

9.	In the given constraint, if the the surface and the pulley are frictionless and the string is inextensible, then velocity of the block Aparallel to the smooth surface is
Answer» In the given constraint, if the the surface and the pulley are frictionless and the string is inextensible, then velocity of the block $A$ parallel to the smooth surface is

Discussion

10.	A photoelectric surface is illuminated successively by monochromatic light of wavelengths λ and λ2. If the maximum kinetic energy of the emitted photoelectrons in the second case is 3 times that in the first case, the work function of the surface of the material is (h = Planck's constant, c = speed of light)
Answer» A photoelectric surface is illuminated successively by monochromatic light of wavelengths $λ$ and $\frac{λ}{2}$ . If the maximum kinetic energy of the emitted photoelectrons in the second case is 3 times that in the first case, the work function of the surface of the material is ( $h$ = Planck's constant, $c$ = speed of light)

Discussion

11.	A satellite is orbiting around the earth in a circular orbit. Its orbital speed is V0. A rocket on board is fired from the satellite which imparts a thrust to the satellite directed radially away from the centre of the earth. The duration of the engine burn is negligible so that it can be considered instantaneous. Due to this thrust, a velocity variation ΔV is imparted to the satellite. The minimum value of the ratio ΔVV0 for which the satellite will escape out of the gravitational field of the earth is
Answer» A satellite is orbiting around the earth in a circular orbit. Its orbital speed is $V_{0}$ . A rocket on board is fired from the satellite which imparts a thrust to the satellite directed radially away from the centre of the earth. The duration of the engine burn is negligible so that it can be considered instantaneous. Due to this thrust, a velocity variation $Δ V$ is imparted to the satellite. The minimum value of the ratio $\frac{Δ V}{V_{0}}$ for which the satellite will escape out of the gravitational field of the earth is

Discussion

12.	An explosion blows a rock into three parts. Two pieces go off at right angles to each other; 1.0 kg piece with a velocity of 12 m/s and other 2.0 kg piece with a velocity 8 m/s. If the third piece flies off with a velocity 40 m/s, compute the mass of third piece.
Answer» An explosion blows a rock into three parts. Two pieces go off at right angles to each other; 1.0 kg piece with a velocity of 12 m/s and other 2.0 kg piece with a velocity 8 m/s. If the third piece flies off with a velocity 40 m/s, compute the mass of third piece.

Discussion

13.	Show that the points A,B,C with position vectors 2^i−^j+^k,^i−3^j−5^k, and 3^i−4^j−4^k respectively,are the vertices of a right-angled triangle. Hence find the area of the rectangle.
Answer» Show that the points A,B,C with position vectors $2^i -^j +^k,^i - 3^j - 5^k,$ and $3^i - 4^j - 4^k$ respectively,are the vertices of a right-angled triangle. Hence find the area of the rectangle.

Discussion

14.	A non conducting ring of mass m, radius R, having charge q uniformly distributed over its circumference is placed on a rough horizontal surface. A vertical time varying magnetic field B=8t2 is switched on at time t = 0. After 3s, the ring starts rotating. The coefficient of friction between the ring and the table is
Answer» A non conducting ring of mass m, radius R, having charge q uniformly distributed over its circumference is placed on a rough horizontal surface. A vertical time varying magnetic field $B = 8 t^{2}$ is switched on at time t = 0. After 3s, the ring starts rotating. The coefficient of friction between the ring and the table is

Discussion

15.	Consider an infinite mesh as shown in the figure. Each side of the mesh has resistance R. Consider hexagonal part ABCDEF of infinite mesh and equivalent resistance between any two points of hexagon is measured. Equivalent resistance between A and B is αRβ. The least value of α+β is .(Here, α & β are whole number)(Answer upto two digits after the decimal point)
Answer» Consider an infinite mesh as shown in the figure. Each side of the mesh has resistance R. Consider hexagonal part ABCDEF of infinite mesh and equivalent resistance between any two points of hexagon is measured. Equivalent resistance between A and B is $\frac{α R}{β}$ . The least value of $α + β$ is .(Here, $α & β$ are whole number)(Answer upto two digits after the decimal point)

Discussion

16.	The total length of potentiometer wire is 10 m. The distance between the null points on the potentiometer wire for two cells is 60 cm. If the difference between the emfs of the cells is 0.4 V, the potential gradient along the wire is____.
Answer» The total length of potentiometer wire is 10 m. The distance between the null points on the potentiometer wire for two cells is 60 cm. If the difference between the emfs of the cells is 0.4 V, the potential gradient along the wire is____.

Discussion

17.	Density of wood is 0.5 g/cc in the CGS system of units. The numerical value of density in MKS system of units is
Answer» Density of wood is $0.5 g/cc$ in the $C G S$ system of units. The numerical value of density in $M K S$ system of units is

Discussion

18.	We have an isolated conducting spherical shell of radius 10 cm. Some positive charge is given to it so that resulting electric field has a maximum intensity of 1.8×106NC−1. The same amount of negative charge is given to another isolated conducting spherical shell of radius 20 cm. Now, first shell is placed inside the second so that both are concentric as shown in the figure.The electric field intensity just inside the outer sphere is
Answer» We have an isolated conducting spherical shell of radius 10 cm. Some positive charge is given to it so that resulting electric field has a maximum intensity of $1.8 \times 10^{6} N C^{- 1} .$ The same amount of negative charge is given to another isolated conducting spherical shell of radius 20 cm. Now, first shell is placed inside the second so that both are concentric as shown in the figure. The electric field intensity just inside the outer sphere is

Discussion

19.	A light body and a heavy body have same linear momentum. Which one has greater K.E.?
Answer» A light body and a heavy body have same linear momentum. Which one has greater K.E.?

Discussion

20.	A car is moving on a straight horizontal road with a speed v. When brakes are applied to give a constant retardation a, the car covers distance S before coming to rest. If the car were moving with a speed 3v and the same retardation a is applied, the distance that the car travels will be
Answer» A car is moving on a straight horizontal road with a speed $v$ . When brakes are applied to give a constant retardation $a$ , the car covers distance $S$ before coming to rest. If the car were moving with a speed $3 v$ and the same retardation $a$ is applied, the distance that the car travels will be

Discussion

21.	A string of length 20 cm and linear mass density 0.40 g cm−1 is fixed at both ends and is kept under a tension of 16 N. A wave pulse is produced at t = 0 near an end as shown in figure (15-E3), which travels towards the other end. (a) When will the string have the shape shown in the figure again ? (b) Sketch the shape of the string at a time half of that found in part (a).
Answer» A string of length 20 cm and linear mass density $0.40 g c m^{- 1}$ is fixed at both ends and is kept under a tension of 16 N. A wave pulse is produced at t = 0 near an end as shown in figure (15-E3), which travels towards the other end. (a) When will the string have the shape shown in the figure again ? (b) Sketch the shape of the string at a time half of that found in part (a).

Discussion

22.	The function sin2ωt represents
Answer» The function $s i n^{2} ω t$ represents

Discussion

23.	A small ball falling vertically downward with constant velocity 4 m/s strikes elastically a massive wedge moving with velocity 4 m/s horizontally as shown. The velocity of the rebound of the ball is
Answer» A small ball falling vertically downward with constant velocity 4 m/s strikes elastically a massive wedge moving with velocity 4 m/s horizontally as shown. The velocity of the rebound of the ball is

Discussion

24.	A solid cube is placed on a horizontal surface. The coefficient of friction between them is μ, where μ<12. A variable horizontal force is applied on the cube’s upper face, perpendicular to one edge and passing through the mid-point of edge, as shown in figure. The maximum acceleration with which it can move without toppling is
Answer» A solid cube is placed on a horizontal surface. The coefficient of friction between them is $μ$ , where $μ < \frac{1}{2}$ . A variable horizontal force is applied on the cube’s upper face, perpendicular to one edge and passing through the mid-point of edge, as shown in figure. The maximum acceleration with which it can move without toppling is

Discussion

25.	The ratio of magnetic inductions at the centre of a circular coil of radius ′a′ and on its axis at a distance equal to its radius, will be
Answer» The ratio of magnetic inductions at the centre of a circular coil of radius $^{'} a^{'}$ and on its axis at a distance equal to its radius, will be

Discussion

26.	Q. Find the gain percent if a dishonest shopkeeper sells the goods at 5% profit but only gives 940 grams for the price of 1 Kg? Q. यदि एक बेईमान दुकानदार 5% लाभ पर सामान बेचता है,लेकिन 1 किलो के बदले केवल 940 ग्राम समान देता है, तो लाभ का प्रतिशत ज्ञात करें?
Answer» Q. Find the gain percent if a dishonest shopkeeper sells the goods at $5 %$ profit but only gives 940 grams for the price of 1 Kg? Q. यदि एक बेईमान दुकानदार $5 %$ लाभ पर सामान बेचता है,लेकिन 1 किलो के बदले केवल 940 ग्राम समान देता है, तो लाभ का प्रतिशत ज्ञात करें?

26.

Q. Find the gain percent if a dishonest shopkeeper sells the goods at 5% profit but only gives 940 grams for the price of 1 Kg? Q. यदि एक बेईमान दुकानदार 5% लाभ पर सामान बेचता है,लेकिन 1 किलो के बदले केवल 940 ग्राम समान देता है, तो लाभ का प्रतिशत ज्ञात करें?

Answer»

Q. Find the gain percent if a dishonest shopkeeper sells the goods at $5 %$ profit but only gives 940 grams for the price of 1 Kg?

Q. यदि एक बेईमान दुकानदार $5 %$ लाभ पर सामान बेचता है,लेकिन 1 किलो के बदले केवल 940 ग्राम समान देता है, तो लाभ का प्रतिशत ज्ञात करें?

Discussion

27.	A metallic ball of mass 20 kg moving with a velocity of 5 m/s collides with a small plastic ball of mass 5 g initially at rest. What is the final velocity of the plastic ball?
Answer» A metallic ball of mass $20 kg$ moving with a velocity of $5 m/s$ collides with a small plastic ball of mass $5 g$ initially at rest. What is the final velocity of the plastic ball?

Discussion

28.	A piece of wood of mass 6 kg is floating in water with its 13rd part inside the water. On this floating piece of wood, what maximum mass can be put such that the whole of the piece of wood gets drowned in the water?
Answer» A piece of wood of mass $6 kg$ is floating in water with its $\frac{1}{3}$ rd part inside the water. On this floating piece of wood, what maximum mass can be put such that the whole of the piece of wood gets drowned in the water?

Discussion

29.	A raft of wood (ρ=600 kg/m3) of mass 120 kg floats on water. The mass which can be put on the raft to make it just sink is
Answer» A raft of wood $(ρ = 600 {kg/m}^{3})$ of mass $120 kg$ floats on water. The mass which can be put on the raft to make it just sink is

Discussion

30.	Density of a liquid in cgs system is 0.625 g per cm cube what is its magnitude in si system
Answer» Density of a liquid in cgs system is 0.625 g per cm cube what is its magnitude in si system

Discussion

31.	A boat floating in a tank of water is carrying passengers. If the passengers drink some of the water surrounding the boat in the tank , how will it affect the water level of the tank?
Answer» A boat floating in a tank of water is carrying passengers. If the passengers drink some of the water surrounding the boat in the tank , how will it affect the water level of the tank?

Discussion

32.	Moment of inertia of a uniform disc of internal radius r and external radius R and mass M about an axis through its centre and perpendicular to its plane is
Answer» Moment of inertia of a uniform disc of internal radius $r$ and external radius $R$ and mass $M$ about an axis through its centre and perpendicular to its plane is

Discussion

33.	A cylindrical tank has a hole of area 1 cm2 at its bottom. If water is allowed to flow into the tank from a tube above it at the rate of 70 cm3/sec, then the maximum height up to which water can rise in the tank is - [Take g=980 cm/s2]
Answer» A cylindrical tank has a hole of area $1 {cm}^{2}$ at its bottom. If water is allowed to flow into the tank from a tube above it at the rate of $70 {cm}^{3} / sec$ , then the maximum height up to which water can rise in the tank is - [Take $g = 980 {cm/s}^{2}$ ]

Discussion

34.	What might happen if sodium is kept in place of gold foil in the Alpha particle scattering experiment which is carried out by Rutherford?
Answer» What might happen if sodium is kept in place of gold foil in the Alpha particle scattering experiment which is carried out by Rutherford?

Discussion

35.	A particle moves with deceleration along the circle of radius R so that at any moment of time its tangential and normal accelerations are equal in moduli. At the initial moment t=0 the speed of the particle equals v0, then the speed of the particle as a function of the distance covered S will be
Answer» A particle moves with deceleration along the circle of radius $R$ so that at any moment of time its tangential and normal accelerations are equal in moduli. At the initial moment $t = 0$ the speed of the particle equals $v_{0}$ , then the speed of the particle as a function of the distance covered $S$ will be

Discussion

36.	At the highest point, water does not fall out of the bucket when rotated in a vertical circle because
Answer» At the highest point, water does not fall out of the bucket when rotated in a vertical circle because

36.

At the highest point, water does not fall out of the bucket when rotated in a vertical circle because

Answer»

At the highest point, water does not fall out of the bucket when rotated in a vertical circle because

Discussion

37.	What is the standard potential of the Tl+3/Tlelectrode? Tl+3+2e−→Tl+ E0=1.26 vTl++e−→Tl E0=−0.336v
Answer» What is the standard potential of the $T l^{+ 3} / T l$ electrode? $T l^{+ 3} + 2 e^{-} \to T l^{+} E^{0} = 1.26 v T l^{+} + e^{-} \to T l E^{0} = - 0.336 v$

37.

What is the standard potential of the Tl+3/Tlelectrode? Tl+3+2e−→Tl+ E0=1.26 vTl++e−→Tl E0=−0.336v

Answer»

What is the standard potential of the $T l^{+ 3} / T l$ electrode?

$T l^{+ 3} + 2 e^{-} \to T l^{+} E^{0} = 1.26 v T l^{+} + e^{-} \to T l E^{0} = - 0.336 v$

Discussion

38.	Liquid is filled in a vessel which is kept in a room with temperature 20o C. When the temperature of the liquid is 80o C, then it loses heat at the rate of 60 cal/sec. What will be the rate of loss of heat when the temperature of the liquid is 40o C
Answer» Liquid is filled in a vessel which is kept in a room with temperature $20^{o} C$ . When the temperature of the liquid is $80^{o} C$ , then it loses heat at the rate of 60 cal/sec. What will be the rate of loss of heat when the temperature of the liquid is $40^{o} C$

Discussion

39.	The radii of two concentric circles spherical conducting shells are r1 and r2 (r1<r2) .The change on the outer shell is q. The charge on the inner shell which is connected to the earth is
Answer» The radii of two concentric circles spherical conducting shells are r1 and r2 (r1<r2) .The change on the outer shell is q. The charge on the inner shell which is connected to the earth is

Discussion

40.	Truth table for the following digital circuit will be
Answer» Truth table for the following digital circuit will be

Discussion

41.	A spring of force constant k is cut into two pieces such that one piece is double the length of the other. Then the long piece will have a force constant of____
Answer» A spring of force constant k is cut into two pieces such that one piece is double the length of the other. Then the long piece will have a force constant of____

Discussion

42.	How to find out the value of log23.4565 from the logarithm table ? explain in detail.
Answer» How to find out the value of log23.4565 from the logarithm table ? explain in detail.

Discussion

43.	The density of air at NTP is 1.3 g/L. Assuming air to be diatomic with γ=1.4, calculate the velocity of sound in air at 27∘C.
Answer» The density of air at $N T P$ is $1.3 g/L$ . Assuming air to be diatomic with $γ = 1.4$ , calculate the velocity of sound in air at $27^{\circ} C$ .

Discussion

44.	A small block of mass m is placed over a long plank of mass M. Coefficient of friction between them is μ. Ground is smooth. At t=0, m is given a velocity v1 and M a velocity v2(>v1) as shown in the figure. After this M is maintained at constant acceleration a(<μg). Find the time t0 when velocities of both block and plank become same.
Answer» A small block of mass $m$ is placed over a long plank of mass $M$ . Coefficient of friction between them is $μ$ . Ground is smooth. At $t = 0$ , $m$ is given a velocity $v_{1}$ and $M$ a velocity $v_{2} (> v_{1})$ as shown in the figure. After this $M$ is maintained at constant acceleration $a (< μ g)$ . Find the time $t_{0}$ when velocities of both block and plank become same.

Discussion

45.	Q. consider a force vector F =i^+j^+k^ .another vector perpendicular of F is
Answer» Q. consider a force vector F =i^+j^+k^ .another vector perpendicular of F is

Discussion

46.	What is the physical meaning of cross product of any two vectors??
Answer» What is the physical meaning of cross product of any two vectors??

Discussion

47.	A liquid flows through a horizontal tube. The velocities of the liquid in the two sections, which have areas of cross-section A1 and A2 are v1 and v2 respectively. The difference in the levels of the liquid in the two vertical tubes is h. A) The volume of the liquid flowing through the tube in unit time is A1v1 B) v2−v1 = √2gh C) v22−v21 = 2gh D) The energy per unit mass of the liquid is the same in both section of the tube.
Answer» A liquid flows through a horizontal tube. The velocities of the liquid in the two sections, which have areas of cross-section $A_{1}$ and $A_{2}$ are $v_{1}$ and $v_{2}$ respectively. The difference in the levels of the liquid in the two vertical tubes is $h$ . A) The volume of the liquid flowing through the tube in unit time is $A_{1} v_{1}$ B) $v_{2} - v_{1}$ = $\sqrt{2 g h}$ C) $v_{2}^{2} - v_{1}^{2}$ = 2gh D) The energy per unit mass of the liquid is the same in both section of the tube.

47.

A liquid flows through a horizontal tube. The velocities of the liquid in the two sections, which have areas of cross-section A1 and A2 are v1 and v2 respectively. The difference in the levels of the liquid in the two vertical tubes is h. A) The volume of the liquid flowing through the tube in unit time is A1v1 B) v2−v1 = √2gh C) v22−v21 = 2gh D) The energy per unit mass of the liquid is the same in both section of the tube.

Answer»

A liquid flows through a horizontal tube. The velocities of the liquid in the two sections, which have areas of cross-section $A_{1}$ and $A_{2}$ are $v_{1}$ and $v_{2}$ respectively. The difference in the levels of the liquid in the two vertical tubes is $h$ .

A) The volume of the liquid flowing through the tube in unit time is $A_{1} v_{1}$

B) $v_{2} - v_{1}$ = $\sqrt{2 g h}$

C) $v_{2}^{2} - v_{1}^{2}$ = 2gh

D) The energy per unit mass of the liquid is the same in both section of the tube.

Discussion

48.	On decreasing temperature ρ decreases in insulator and semiconductor. Why?
Answer» On decreasing temperature $ρ$ decreases in insulator and semiconductor. Why?

Discussion

49.	The pulley shown in the figure has a radius of 20 cm and moment of inertia 0.2 kg-m2. The string going over it is attached at one end to a vertical spring of spring constant 50 N/m fixed from below, and supports a 1 kg mass at the other end. The system is released from rest with the spring at its natural length. Find the speed of the block when it has descended through 10 cm. Take g = 10 m/s2 .
Answer» The pulley shown in the figure has a radius of 20 cm and moment of inertia 0.2 kg- $m^{2}$ . The string going over it is attached at one end to a vertical spring of spring constant 50 N/m fixed from below, and supports a 1 kg mass at the other end. The system is released from rest with the spring at its natural length. Find the speed of the block when it has descended through 10 cm. Take g = 10 $m / s^{2}$ .

49.

The pulley shown in the figure has a radius of 20 cm and moment of inertia 0.2 kg-m2. The string going over it is attached at one end to a vertical spring of spring constant 50 N/m fixed from below, and supports a 1 kg mass at the other end. The system is released from rest with the spring at its natural length. Find the speed of the block when it has descended through 10 cm. Take g = 10 m/s2 .

Answer»

The pulley shown in the figure has a radius of 20 cm and moment of inertia 0.2 kg- $m^{2}$ . The string going over it is attached at one end to a vertical spring of spring constant 50 N/m fixed from below, and supports a 1 kg mass at the other end. The system is released from rest with the spring at its natural length. Find the speed of the block when it has descended through 10 cm. Take g = 10 $m / s^{2}$

.

Discussion

50.	A particle starts moving rectilinearly at time t = 0 such that its velocity ‘v’ changes with time ‘t’ according to the equation v=t2−t where t is in seconds and v in m/s. Find the time interval for which the particle retards.
Answer» A particle starts moving rectilinearly at time t = 0 such that its velocity ‘v’ changes with time ‘t’ according to the equation $v = t^{2} - t$ where t is in seconds and v in m/s. Find the time interval for which the particle retards.

Discussion

Explore topic-wise InterviewSolutions in Current Affairs.

A block of mass m starts sliding on the plank of mass M. There is a sufficient friction between plank and the block. After some time both block and plank moves together. Choose the correct statement

A concave mirror is placed at the bottom of an empty tank with face upwards and axis vertical. When sunlight falls normally on the mirror, it is focussed at distance of 32 cm from the mirror. If the tank filled with water (μ=43) upto a height of 20 cm, then the sunlight will now get focussed at

The focal lengths of a convex lens for red, yellow and violet rays are 100 cm, 98 cm and 96 cm respectively. Find the dispersive power of the material of the lens.

Two discs of mass 2 kg and 3 kg of radius 1 m and 2 m respectively placed together are rotated about an axis through their common centre as shown in figure. Find the net moment of inertia of the system about given axis.

A charged particle is whirled anticlockwise in a horizontal circle on a frictionless table by attaching it to a string fixed at one point. What will happen to the tension in the string, if a magnetic field is switched on in the vertical direction?

In the arrangement shown in figure, mA=4 kg and mB=1 kg. The system is released from rest and block B is found to have a speed of 0.3 m/s after it has descended through a distance of 1 m. Find the coefficient of friction between the block and the table. Neglect friction elsewhere. (Take g=10 m/s2).

In the given constraint, if the the surface and the pulley are frictionless and the string is inextensible, then velocity of the block Aparallel to the smooth surface is

An explosion blows a rock into three parts. Two pieces go off at right angles to each other; 1.0 kg piece with a velocity of 12 m/s and other 2.0 kg piece with a velocity 8 m/s. If the third piece flies off with a velocity 40 m/s, compute the mass of third piece.

Show that the points A,B,C with position vectors 2^i−^j+^k,^i−3^j−5^k, and 3^i−4^j−4^k respectively,are the vertices of a right-angled triangle. Hence find the area of the rectangle.

The total length of potentiometer wire is 10 m. The distance between the null points on the potentiometer wire for two cells is 60 cm. If the difference between the emfs of the cells is 0.4 V, the potential gradient along the wire is____.

Density of wood is 0.5 g/cc in the CGS system of units. The numerical value of density in MKS system of units is

A light body and a heavy body have same linear momentum. Which one has greater K.E.?

A car is moving on a straight horizontal road with a speed v. When brakes are applied to give a constant retardation a, the car covers distance S before coming to rest. If the car were moving with a speed 3v and the same retardation a is applied, the distance that the car travels will be

The function sin2ωt represents

A small ball falling vertically downward with constant velocity 4 m/s strikes elastically a massive wedge moving with velocity 4 m/s horizontally as shown. The velocity of the rebound of the ball is

The ratio of magnetic inductions at the centre of a circular coil of radius ′a′ and on its axis at a distance equal to its radius, will be

A metallic ball of mass 20 kg moving with a velocity of 5 m/s collides with a small plastic ball of mass 5 g initially at rest. What is the final velocity of the plastic ball?

A piece of wood of mass 6 kg is floating in water with its 13rd part inside the water. On this floating piece of wood, what maximum mass can be put such that the whole of the piece of wood gets drowned in the water?

A raft of wood (ρ=600 kg/m3) of mass 120 kg floats on water. The mass which can be put on the raft to make it just sink is

Density of a liquid in cgs system is 0.625 g per cm cube what is its magnitude in si system

A boat floating in a tank of water is carrying passengers. If the passengers drink some of the water surrounding the boat in the tank , how will it affect the water level of the tank?

Moment of inertia of a uniform disc of internal radius r and external radius R and mass M about an axis through its centre and perpendicular to its plane is

A cylindrical tank has a hole of area 1 cm2 at its bottom. If water is allowed to flow into the tank from a tube above it at the rate of 70 cm3/sec, then the maximum height up to which water can rise in the tank is - [Take g=980 cm/s2]

What might happen if sodium is kept in place of gold foil in the Alpha particle scattering experiment which is carried out by Rutherford?

A particle moves with deceleration along the circle of radius R so that at any moment of time its tangential and normal accelerations are equal in moduli. At the initial moment t=0 the speed of the particle equals v0, then the speed of the particle as a function of the distance covered S will be

At the highest point, water does not fall out of the bucket when rotated in a vertical circle because

What is the standard potential of the Tl+3/Tlelectrode? Tl+3+2e−→Tl+ E0=1.26 vTl++e−→Tl E0=−0.336v

Liquid is filled in a vessel which is kept in a room with temperature 20o C. When the temperature of the liquid is 80o C, then it loses heat at the rate of 60 cal/sec. What will be the rate of loss of heat when the temperature of the liquid is 40o C

The radii of two concentric circles spherical conducting shells are r1 and r2 (r1&lt;r2) .The change on the outer shell is q. The charge on the inner shell which is connected to the earth is

Truth table for the following digital circuit will be

A spring of force constant k is cut into two pieces such that one piece is double the length of the other. Then the long piece will have a force constant of____

How to find out the value of log23.4565 from the logarithm table ? explain in detail.

The density of air at NTP is 1.3 g/L. Assuming air to be diatomic with γ=1.4, calculate the velocity of sound in air at 27∘C.

Q. consider a force vector F =i^+j^+k^ .another vector perpendicular of F is

What is the physical meaning of cross product of any two vectors??

On decreasing temperature ρ decreases in insulator and semiconductor. Why?

A particle starts moving rectilinearly at time t = 0 such that its velocity ‘v’ changes with time ‘t’ according to the equation v=t2−t where t is in seconds and v in m/s. Find the time interval for which the particle retards.

The radii of two concentric circles spherical conducting shells are r1 and r2 (r1<r2) .The change on the outer shell is q. The charge on the inner shell which is connected to the earth is