Explore topic-wise InterviewSolutions in Current Affairs.

The wavelength is 120 cm when the source is stationary. If the source is moving with relative velocity of 60 m/sec towards the observer, then the wavelength of the sound wave reaching to the observer will be (velocity of sound = 330 m/s)

An earth satellite of mass m revolves in a circular orbit at a height h from the surface of the earth. R is the radius of the earth and g is acceleration due to gravity at the surface of the earth. The velocity of the satellite in the orbit is given by

A train running at 108 km $h^{-1}$ towards east whistles at a dominant frequency of 600 Hz. Speed of sound in air is 340 m/s. What frequency will a passenger sitting near the open window hear ? (b) What frequency will a person standing near the track hear whom the train has just passed ? (c) A wind starts blowing towards east at a speed of 36 km $h^{-1}$. Calculate the frequencies heard by the passenger in the train and by the person standing near the track.

A proton is projected with a velocity of $3\times {10}^{6}m{s}^{-1}$ perpendicular to a uniform magnetic field of 0.6 T. Find the acceleration of the proton.

In the given setup find the tension in the left and the right string? Assume string and pulley to be massless, surface and pulleys are frictionless.

k transparent slabs are arranged one over another. The refractive indices of the slabs are ${\mu }_1,{\mu }_2,{\mu }_3,\dots \dots {\mu }_k$ and the thickness are $t_1,t_2,t_3,\dots \dots t_k$. An object is seen through this combination with nearly perpendicular light. Find the equivalent refractive index of the system which will allow the image to be formed at the same place.

A body is at rest at $x=0$. At $t=0$, it starts moving in the positive x-direction with a constant acceleration. At the same instant another body passes through $x=0$ moving in the positive x-direction with a constant speed. The position of the first body is given by $x_1\left(t\right)$ after time $t$ and that of the second body by $x_2\left(t\right)$ after the same time interval. Which of the following graphs correctly describes $(x_1-x_2)$ as a function of time $t$?

In the figure, all pulleys are massless and strings are light.
$\begin{array}{cc}\text{Column-I}& \text{Column-II}\\ \text{(a) 1 kg block}& \text{(p)}\text{will remain stationary}\\ \text{(b) 2 kg block}& \text{(q)}\text{will move down}\\ \text{(c) 3 kg block}& \text{(r)}\text{will move up}\\ \text{(a) 4 kg block}& \text{(s)}5{\text{m/s}}^2\\ & \text{(t)}10{\text{m/s}}^2\end{array}$

Prove the following question.

${\int }_0^{1}si{n}^{-1}xdx=\frac{\pi }{2}-1.$

A person walks up a stalled escalator in $90s$ . When just standing on the same moving escalator, he is carried in $60s$. The time it would take him to walk up the moving escalator will be

Energy stored in spring $A=20\text{J}$, then energy stored in spring $B$ is (under same extension of the spring)

In a diffraction pattern due to a single slit of width a, the first minimum is observed at an angle ${30}^{\circ }$ when light of wavelength $5000\stackrel{\circ }{A}$ is incident on the slit. The first secondary maximum is observed at an angle of

A shell of mass 0.020 kg is fired by a gun of mass 100 kg. If the muzzle speed of the shell is $80m{s}^{-1}$, what is the recoil speed of the gun?

Write the dimensions of a × b in the relation $E=\frac{b-x^2}{at}$, where E is the energy, x is the displacement and t is time.

A man wants to swim across a river from A to B and back from B to A always following line AB. The distance S between points A and B is S. The velocity of the river current v is constant over the entire width of the river. The line AB makes an angle $\alpha$ with the direction of current. Let the man travel with velocity u and at angle $\beta$ to the line AB. Find time 't' by which he will be back.

A vertical capillary with inside diameter 0.50mm is submerged in to water so that the length of its part emerging outside the water surface is equal to 25mm.Find the radius of curvature of the meniscus. Surface tension of water is $73\times {10}^{-3}N/m(g=9.8m/s^2)$

Find the area bounded by the curve y = $e^{-x}$, the X -axis and the Y-axis.

A 50 kg girl wearing high heel shoes balances on a single heel. The heel is circular with a diameter 1.0 cm. What is the pressure exerted by the heel on the horizontal floor?

Two spherical bodies of mass $m$, $5m$ and radius $R$, $2R$ respectively are released in free space with an initial separation of $12R$ between their centres. If they attract each other due to gravitational force alone, then the distance covered by the smaller body just before the collision is

10 moles of oxygen $(O_2$) gas is being expanded in a container, maintained at a constant pressure, by supplying 500J of heat. What is the rise in the gas' temperature? Assume the atoms do not oscillate along the bond axis, and the gas is pretty much ideal

if an ammeter is connected between 2 cells in a circuit what will happen?

A metallic wire of density 'd' floats in a fluid of surface tension T. the maximum radius of the wire so that it may not sink is? Assume that the surface of fluid is vertical at the points of contact with the metal wire.

When a chalk piece is immersed in water bubbles are emitted,why?

A geostationary satellite is orbiting the earth at a height of 6R above the surface of the earth; R being the radius of the earth. What will be the time period of another satellite at a height 2.5 R from the surface of the earth?

A particle moving in a straight line has velocity and displacement equation as V = 4 $\sqrt{1+S}$ , where V in m/s and s is in m.

The initial velocity of the particle in m/s is ______

Star $S_1$ emits maximum radiation of wavelength $420\text{nm}$ and the star $S_2$ emits maximum radiation of wavelength $560\text{nm}$, what is the ratio of the temperature of $S_1$ and $S_2$ :

A solid sphere (radius = R) rolls without slipping in a cylindrical through (radius = 5R). Find the time period of small oscillations.

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The position, velocity and acceleration of a particle executing simple harmonic motion are found to have magnitudes $2cm,1m{s}^{-1}and10m{s}^{-2}$ at a certain instant. Find the amplitude and the time period of the motion.

Two very long straight parallel wires carry currents of same magnitude and in the same direction. The distance between the wires is d. At a certain instant of time, a point charge q is at a point equidistant from the two wires, in the plane of the wires. Its instantaneous velocity $\overrightarrow{v}$ is perpendicular to this plane. The magnitude of the force due to magnetic field acting on the charge at this instant is

The position of a particle moving in a straight line is described by the relation $x=6+12t-2t^2\text{m}$. The distance covered by the particle in first $5\text{s}$ is

The equation of motion of a particle is $\frac{d^{2}y}{d{t}^2}+Ky=0$ , where K is positive

constant. The time period of the motion is given by

A quantity of heat required to change the unit mass of a solid substance, from solid state to liquid state, while the temperature remains constant, is known as the _______.

If $\overrightarrow{a},\overrightarrow{b},\overrightarrow{c}$are three mutually perpendicular unit vectors, then $|\overrightarrow{a}+\overrightarrow{b}+\overrightarrow{c}|$ is equal to

If $y={\sin }^2\theta +{\cos }^3\theta$. Find $\frac{dy}{d\theta }$.

Match the following.

$\begin{array}{cc}Column-I& Column-II\\ \left(A\right)Concavemirror,realobject& \left(p\right)realimage\\ \left(B\right)Concavemirror,realobject& \left(q\right)virtualimage\\ \left(C\right)Concavelens,realobject& \left(r\right)magnifiedimage\\ \left(D\right)Convexlens,realobject& \left(s\right)diminishedimage\end{array}$

The potential difference applied to an X-ray tube in 5kV and the current through it is 3.2mA. Then the number of electrons striking the target per second is

A ray of light is approaching a set of three mirrors as shown in the diagram. The light ray is approaching the first mirror at an angle of ${45}^{\circ }$ with the mirror surface. How many times will the ray reflect before it exits the system?

A body of mass '$m$' and radius '$r$' is released from rest along a smooth inclined plane of angle of inclination $\theta$. 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)

A solid sphere of radius R and made of a material of bulk modulus K is completely immersed in a liquid in a cylindrical container. A massless piston of area A floats on the surface of the liquid. When a mass M is placed on the piston to compress the liquid, the fractional change in the radius of the sphere, $\frac{\delta R}{R}$ is given by

A particle of mass m is executing oscillations about the origin on the x-axis. Its potential energy is U(x) = k $[x{]}^3$ , where k is a positive constant. If the amplitude of oscillation is a, then its time period T is

A body of mass m kg. starts falling from a point 2R above the Earth's surface. Its kinetic energy when it has fallen to a point 'R' above the Earth's surface [R-Radius of Earth, M-Mass of Earth, G-Gravitational Constant]

A body of mass 5 kg is moving with a momentum of 10 kg-m/s.A force of 0.2 N acts on it in the direction of motion of the body for 10 seconds. The increase in its kinetic energy is

A block of mass $4kg$ slides down a plane inclined at ${37}^{\circ }$ with the horizontal. The length of plane is $3m$. The coefficient of sliding friction between the block and the plane is $0.2$. Find the work done by gravity and the frictional force on the block.

A uniform chain of length L and mass M is lying on a smooth table and one third of its length is hanging vertically down over the edge of the table. If g is acceleration due to gravity, the work required to pull the hanging part on to the table is