Recent questions in Physics

There are two holes one each along the opposite sides of a wide rectangular tank. The cross- section of each hole is $0.01m^2$ and the vertical distance between the holes is one meter. The tank is filled with water the net force on the tank in newton when the water flows out of the holes is : (Density of water $=1000\;kg/m^3)$

asked Nov 13, 2013 by meena.p

1 answer

Water in a river 20 m deep is flowing at a speed of $10\;ms^{-1}$. The shearing stress between the horizontal layers of water in the river in $Nm^{-2}$ is : (Coefficient of viscosity of water $=10^{-3}SI$ units)

asked Nov 13, 2013 by meena.p

0 answers

One end of a uniform glass capillary tube of radius $r=0.025\;cm$ is immersed vertically in water to a depth $h=1\;cm$. The excess pressure in $N/m^2$ required to blow an air bubble out of the tube: (Surface tension of water$= 7 \times 10^{-2} N/m$ Density of water$= 10^3 kg/m^3$ Acceleration due to gravity $=10 m/s^2$)

asked Nov 13, 2013 by meena.p

1 answer

One end of a uniform glass capillary tube of radius $r=0.025\;cm$ is immersed vertically in water to a depth $h=1\;cm$. The excess pressure in $N/m^2$ required to blow an air bubble out of the tube: (Surface tension of water$= 7 \times 10^{-2} N/m$ Density of water$= 10^3 kg/m^3$ Acceleration due to gravity $=10 m/s^2$)

asked Nov 13, 2013 by meena.p

0 answers

A metalic ring of radius r and cross sectional area A is fitted into a wooden circular disc of radius $R(R > 1)$. If the Young's modulus of the material of the ring is Y, the force with which the metal ring expands is :

asked Nov 13, 2013 by meena.p

1 answer

The time period of a simple pendulum is T. When the length is increased by 10 cm,its period is $T_1$. When the length is decreased by 10 cm, its period is $T_2$. Then, the relation between $T,T_1\;and T_2$ is :

asked Nov 13, 2013 by meena.p

1 answer

The escape velocity of a body on the earth's surface is $v_e$. A body is thrown up with a speed $\sqrt 5 v_c$. Assuming that the sun and planets do not influence the motion of the body, velocity of the body at infinite distance, is :

asked Nov 13, 2013 by meena.p

1 answer

A particle of mass 1 kg is projected with an initial velocity $10\;ms^{-1}$ at an angle of projection $45^{\circ}$ with the horizontal. The average torque acting on the projectile, between the time at which it is projected and the time at which it strikes the ground, about the point of projection in newton-meter is :

asked Nov 13, 2013 by meena.p

1 answer

A thin uniform square lamina of side a is placed in the xy-plane with its sides parallel to x and y-axes and with its center coinciding with origin. Its moment of inertia about an axis passing through a point on the y-axis at a distance $y=2a$ and parallel to x-axis is equal to its moment of inertia about an axis passing through a point on the x-axis at a distance $x=d$ and perpendicular to xy-plane. Then value of d is :

asked Nov 13, 2013 by meena.p

1 answer

Consider the following statements A and B and identify the correct answer:A : When a person walks on a rough surface the direction of frictional force exerted by the surface on the person is opposite to the direction of his motion. B : When a cycle is in motion, the force of friction exerted by the ground on the front wheel is in the backward direction:

asked Nov 13, 2013 by meena.p

1 answer

Two particles of equal mass have velocities $\overrightarrow {v_1}=4 \hat i$ and $\overrightarrow{v_2} =4 \hat j ms^{-1}$. First particle has an acceleration $\overrightarrow{a_1}=(5 \hat i+5 \hat j)ms^{-2}$ while the accleration of the other particle is zero. The center of mass of the two particles moves in a path of :

asked Nov 13, 2013 by meena.p

1 answer

The block of mass 2 kg is initially at rest on a horizontal force $\overrightarrow {F}=(9-x^2) \hat i$ newtons acts on it, when the block is at $x=0$. The maximum kinetic energy of the block between $x=0$ and $x=3m$ in joule is :

asked Nov 13, 2013 by meena.p

1 answer

A 2 kg ball moving at $24 ms^{-1}$ undergoes inelastic head-on collision with a 4 kg ball moving in the opposite direction at $48\;ms^{-1}$. If the coefficient of restitution is $2/3$, their velocities in $ms^{-1}$ after impact are :

asked Nov 13, 2013 by meena.p

1 answer

The horizontal and vertical displacements x and y of a projectile at a given time t are given by $x=6t$ meter and $y=8 t -5t^2$ metre. The range of the projectile in meter is :

asked Nov 13, 2013 by meena.p

1 answer

At a given instant of time two particles are having the position vectors $4 \hat i+4 \hat j+57 \hat k$ metres and $2 \hat i+2 \hat j+5 \hat k$ respectively. If the velocity of the first particle be $0.4 \hat i ms^{-1},$ the velocity of second particle in meter per second if they collide after 10 sec is :

asked Nov 13, 2013 by meena.p

1 answer

The position of a particle at time t is given by the equation $x(t) =\large\frac{v_0}{A}$$(1-e^{At})\; v_0=$ constant and $A > 0$ . Dimensions of $v_0$ and $A$ respectively are:

asked Nov 13, 2013 by meena.p

0 answers

An n-p-n transistor power amplifier in C-E configuration gives :

asked Nov 8, 2013 by meena.p

1 answer

Particles and their anti- particles have:

asked Nov 8, 2013 by meena.p

1 answer

A particle of mass $1 \times 10^{-26}\;kg$ and charge $1.6 \times 10^{-19} C$ travelling with a velocity $1.28 \times 10^{6} ms^{-1}$ along the positive X-axis enters a region in which a uniform electric field $\overrightarrow {E} $ and a uniform magnetic field of induction $\overrightarrow {B}$ are present. If $\overrightarrow {E} =-102.4 \times 10^3 \hat k NC^{-1}$ and $B= 8 \times 10^{-2}\; \hat j Wbm^{-2}$, the direction of motion of the particles is :

asked Nov 8, 2013 by meena.p

1 answer

According to Moseley's law, the frequency (v) of the $K_{\alpha}$ line and the atomic number Z of the element have the relation (A and B are constants);

asked Nov 8, 2013 by meena.p

0 answers

Magnetic field induction at the center of a circular coil of radius 5 cm and carrying a current 0.9 A is (in SI units) ($\in _0$= absolute permittivity of air in SI units, velocity of light $= 3 \times 10^8 ms^{-1})$

asked Nov 8, 2013 by meena.p

1 answer

Two parallel rails of a railway track insulated from each other and with the ground are connected to a millivoltmeter. The distance between the rails is one meter. A train is travelling with a velocity of 72 km/h along the track. The reading of the millivoltmeter (in mV) is : (Vertical component of the earth's magnetic induction is $2 \times 10^{-5} T)$

asked Nov 8, 2013 by meena.p

1 answer

An inductance 1 H is connected in series with an AC source of 220 V and 50Hz. The inductive reactance (in ohms) is :

asked Nov 8, 2013 by meena.p

1 answer

Consider the following statements A and B and identify the correct answers given below: A: Peltier coefficient is numerically equal to the potential difference across the junctions of the thermonuclear through which current is flowing. B:According to Thomson, energy is neither absorbed nor evelved at the junction of a thermocouple but is observed or evolved only along the lengths of both the conductors.

asked Nov 8, 2013 by meena.p

1 answer

In a meter bridge a $30\;\Omega$ resistance is connected in the left gap and a pair of resistances P and Q in the right gap. Measured from the left, the balance point is 37.5 cm , when P and Q are in series and $71.4\;cm$ when they the parallel. The values of P and Q (in $\Omega$) are :

asked Nov 8, 2013 by meena.p

1 answer

A 6 V cell with $0.5 \Omega$ internal resistance, a 10 V cell with $1 \Omega$ internal resistance and a $12 \Omega$ external resistance are connected in parallel. The current (in ampere) through the 10 V cell is :

asked Nov 8, 2013 by meena.p

1 answer

Two charges 2 C and 6C are separated by a finite distance. If a charge of $-4C$ is added to each of them, the initial force of $12 \times 10^3\;N$ will change to :

asked Nov 7, 2013 by meena.p

1 answer

A 4 $\mu F$ capacitor is charged by a 200 V battery. It is then disconnected from the supply and is connected to another uncharged $2\; \mu F$ capacitor. During the process, loss of energy (in J) is :

asked Nov 7, 2013 by meena.p

1 answer

If two identical bar magnets, each of length l, pole strength m, and magnetic moment M are placed perpendicular to each other with their unlike poles in contact, the magnetic moment of the combination is :

asked Nov 7, 2013 by meena.p

1 answer

With a standard rectangular bar magnet of length (l), breath (b ; b < < l) and magnetic moment M, the time period of the magnet in a vibration magnetometer is 4 s. If the magnet is cut normal to its length into four equal pieces, the time period (in seconds) with one of the pieces is :

asked Nov 7, 2013 by meena.p

1 answer

A light ray of wavelength $ \lambda$ is passing through a pin hole of diameter D and the effect is observed on a screen placed at a distance L from the pin hole. The approximations of geometrical optics are applicable if :

asked Nov 7, 2013 by meena.p

1 answer

Fraunhofer lines are produced by the absorption of light in :

asked Nov 7, 2013 by meena.p

0 answers

The focal length of an equi-convex lens is greater than the radius of curvature of any of the surfaces. Then the refractive index of the material of the lens is :

asked Nov 7, 2013 by meena.p

1 answer

Assertion (A) :Propagation of light through an option fibre is due to total internal reflection taking place place at the core-clad interface. Reason (R): Refractive index of the material of the core of the optical fibre is greater than that of air .

asked Nov 7, 2013 by meena.p

0 answers

A transverse wave propagating on a stretched string of linear density $3 \times 10^{-4}\;kg-m^{-1}$ is represented by the equation $y=0.2 \sin (15 x +60 l)$ where x is in meters and l is in seconds . The tension in the string (in newton) is :

asked Nov 7, 2013 by meena.p

1 answer

A vehicle sounding a whistle of frequency 256 Hz is moving on a straight road, towards a hill with a velocity of $10\;ms^{-1}$. The number of beats per second observed by a person travelling in the vehicle is : (Velocity of sound=330 \;ms^{-1})

asked Nov 7, 2013 by meena.p

1 answer

Two identical bodies have temperatures $277^{\circ}C $ and $67^{\circ}C$. If the surroundings temperature is $27^{\circ}C$, the ratio of loss of heats of the two bodies during the same interval of time is (approximately) :

asked Nov 7, 2013 by meena.p

1 answer

The tyre of a motor car contains air at $15^{\circ}C$. If the temperature increases to $35^{\circ}C$ the approximate percentage increase in pressure is (ignore to expansion of tyre):

asked Nov 7, 2013 by meena.p

1 answer

The ratio of specific heats of a gas is $ \gamma$. The change in internal energy of one mole of the gas, when the volume changes from V to 2V at constant pressure P is :

asked Nov 7, 2013 by meena.p

1 answer

The relation between the coefficient of real expansion $(\gamma_r)$ and coefficient of apparent expansion $(\gamma _a)$ of a liquid and the coefficient of linear expansion $(\alpha _g)$ of the material of the container is :

asked Nov 7, 2013 by meena.p

1 answer

An iron sphere of mass $20 \times 10^{-3}\;kg$ falls through a viscous liquid with terminal velocity $0.5\;ms^{-1}.$ The terminal velocity $(in\; ms^{-1})$ of another iron sphere of mass $54 \times 10^{-2}\;kg$ is :

asked Nov 7, 2013 by meena.p

1 answer

The heat evolved for the rise of water when one end of the capillary tube of radius r is immersed vertically into water is : (Assume surface tension=T and density of water to be p)

asked Nov 7, 2013 by meena.p

1 answer

The radii and Young's moduli of two uniform wires A and B are in the ratio 2: 1 and 1:2 respectively. Both wires are subjected to the same longitudinal force. If the increase in length of the wire A is one percent, the percentage in length of the wire B is :

asked Nov 7, 2013 by meena.p

1 answer

A body of mass m is is suspended to an ideal spring of force constant k. The expected change in the position force F acting vertically downwards is :

asked Nov 7, 2013 by meena.p

1 answer

Degenerate electron pressure will not be sufficient to prevent core collapse of white dwarf if its mass becomes n times of solar mass. Value of n is :

asked Nov 7, 2013 by meena.p

1 answer

Identify the increasing order of the angular velocities of the following :

asked Nov 7, 2013 by meena.p

1 answer

The instantaneous velocity of a point B of the given rod of length 0.5 m is 3 m/s in the represented direction. The angular velocity of the rod for the minimum velocity of end A is

asked Nov 7, 2013 by meena.p

1 answer

The minimum force required to move a body up an inclined plane is three times the minimum force required to prevent it from sliding down the plane. If the coefficient of friction between the body and the inclined plane is $\large\frac{1}{2 \sqrt 3},$ the angle of the inclined plane is :

asked Nov 7, 2013 by meena.p

1 answer

Consider the following statements A and B and identify the correct answer: (A): In an elastic collision , if a body suffers a head on collision with another of same mass at rest, the first body comes to rest while the other starts moving with the velocity of the first one . (B): Two bodies of equal mass suffering a head on elastic collision merely exchanges their velcities :

asked Nov 7, 2013 by meena.p

1 answer

The center of mass of three particles of masses 1 kg,2 kg and 3 kg is at (2,2,2). The position of the fourth mass of 4 kg to be placed in the system as that the new center of mass is at (0,0,0) is :

asked Nov 7, 2013 by meena.p

2 answers

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