Recent questions in JEEMAIN and NEET

A particle of mass 10 g is kept on the surface of a uniform sphere of mass 100 kg and radius 10 cm. Find the work to be done against the gravitational force between them, to take the particle far away from the sphere : (you may take $G=6.67 \times 10^{-11}\; Nm^2/kg^2$)

asked Nov 5, 2018 by pady_1

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The change in the value of $g$ at a height $h$ above the surface of the earth is the same as at a depth $d$ below the surface of earth. When both $d$ and $h$ are much smaller than the radius of earth, then which one of the following is correct ?

asked Nov 5, 2018 by pady_1

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A $T$ shaped object with dimensions shown in figure, is lying on a smooth floor. A force $\overrightarrow{F}$ is applied at the point $P$ parallel to $AB$, such that the object has only the translational motion without rotation. Find the location of $P$ with respect to $C$: <br>

asked Nov 5, 2018 by pady_1

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Which of the following is incorrect regarding the first law of thermodynamics ?

asked Nov 5, 2018 by pady_1

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Consider a car moving on a straight road with a speed of 100 m/s. The distance at which car can be stopped , is : $[\mu_k = 0.5]$

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A body of mass m is accelerated uniform from rest to a speed $\nu$ in a time $T$. The instantaneous power delivered to the body as a function of time, is given by :

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Average density of the earth :

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If $S$ is stress and $Y$ is Young's modulus of material of a wire, the energy stored in the wire per unit volume is :

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A 20 cm long capillary tube is dipped in water. The water rises upto 8 cm. If the entire arrangement is put in a freely falling elevator, the length of water column in the capillary tube will be :

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A mass m moves with a velocity $\nu$ and collides inelastically with another identical mass. After collision the $I^{st}$ mass moves with velocity $\frac{\nu}{\sqrt{3}}$ in a direction perpendicular to the initial direction of motion. Find the speed of the second mass after collision :

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The block of mass M moving on the frictionless horizontal surface collides with the spring of spring constant $k$ and compresses it by length $L$. The maximum momentum of the block after collision is : <br>

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A particle of mass $0.3 \;kg$ is subjected to a force $F = -kx$ with $k = 15\; N/m$. What will be its initial acceleration, if it is released from a point 20 cm away from the origin ?

asked Nov 5, 2018 by pady_1

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The moment of inertia of uniform semicircular disc of mass M and radius r about a line perpendicular to the plane of the disc through the centre is :

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A body A of mass M while falling vertically downwards under gravity breaks into two parts; a body B of mass $\frac{1}{3} M$ and, a body C of mass $\frac{2}{3}M$. The centre of mass of body B and C taken together shifts compared to that of body A towards :

asked Nov 5, 2018 by pady_1

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A spherical ball of mass 20 kg is stationary at the top of a hill of height 100 m. It rolls down a smooth surface to the ground, then climbs up another hill of height 30 m and finally rolls down to a horizontal base at a height of 20 m above the ground. The velocity attained by the ball is :

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A block is kept on a frictionless inclined surface with angle of inclination $\propto$. The incline is given an acceleration $a$ to keep the block stationary. Then $a$ is equal to : <br>

asked Nov 5, 2018 by pady_1

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A parachutist after bailing out falls 50 m without friction. When parachute opens, it decelerates at $2\;m/s^2$. he reaches the ground with a speed of $3 \; m/s$. At what height, did he bail out ?

asked Nov 5, 2018 by pady_1

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A particle is moving eastwards with a velocity of $5\; ms^{-1}$. In $10 \;s$ the velocity changes to $5\;ms^{-1}$ northwardas. The average acceleration in this time is:

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A car starting from rest, accelerates at the rate $f$ through a distance $S$, then continues at constant speed for time $t$ and then decelerates at the rate $f/2$ to come to rest. If the total distance travelled is $15 \;S$, then :

asked Nov 5, 2018 by pady_1

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The relation between time $t$ and distance $x$ is $t=ax^2+bx$, where $a$ and $b$ are constants. The acceleration is :

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Out of the following pairs, which one does not have identical dimensions ?

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A bullet fired into a fixed target loses half of its velocity after penetrating 3 cm. How much further it will penetrate before coming to rest, assuming that it faces constant resistance to motion ?

asked Nov 5, 2018 by pady_1

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The upper half of an inclined plane with inclination $\phi$ is perfectly smooth, while the lower half is rough. A body starting from rest at the top will again come to rest at the bottom, if the coefficient of friction for the lower half is given by :

asked Nov 5, 2018 by pady_1

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A smooth block is released at rest on a $45^{\circ}$ incline and then slides a distance $d$. The time taken to slide is $n$ times as much to slide on rough inclined than on a smooth incline. The coefficient of friction is :

asked Nov 5, 2018 by pady_1

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An annular ring with inner and outer radii $R_1$ and $R_2$ is rolling without slipping with a uniform angular seed. The ratio of the forces experienced by the two particles situated on the inner and outer parts of the ring, $\frac{F_1}{F_2}$ is :

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A projectile can have the same range R for two angles of projection. If $t_1$ and $t_2$ be the times of flights in the two cases, then the product of the two times of flights is proportional to :

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When p-n junction diode is forward biased

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The manifestation of band structure in solids is due to

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A piece of copper and another of germanium are cooled from room temperature to 77 K, the resistance of

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For a transistor amplifier in common emitter configuration having load impedance of $1 \; k \Omega\; (h_{fe} = 50$ and $h_{oe} = 25)$ the current gain is

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When npn transistor is used as amplifier

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An $\alpha$-particle of energy $5 \;MeV$ is scattered through $180^{\circ}$ by a fixed uranium nucleus. The distance of the closest approach is of the order of

asked Nov 5, 2018 by pady_1

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The binding energy per nucleon of deuteron $(_1^2H)$ and helium nucleus $(_2^4 He)$ is $1.1\; MeV$ and $7\; MeV$ respectively. If two deuteron nuclei react to form a single helium nucleus, then the energy released is

asked Nov 5, 2018 by pady_1

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A nucleus disintegrates into two nuclear parts which have their velocities in the ratio $2:1$. The ratio of their nuclear sizes will be

asked Nov 5, 2018 by pady_1

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A charged oil drop is suspended in a uniform field of $3 \times 10^4 V/m$ so that it neither falls nor rises. The charge on the drop will be (take the mass of the charge = $9.9 \times 10^{-15} kg$ and $g = 10\;m/s^2$)

asked Nov 5, 2018 by pady_1

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The work function of a substance is 4.0 eV. Then longest wavelength of light that can cause photoelectron emission from this substance approximately

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According to Einstein's photoelectric equation, the plot of the kinetic energy of the emitted photo electrons from a metal $V_s$ the frequency, of the incident radiation gives straight line whose slope

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A metal conductor of length 1 m rotates vertically about one of its ends at angular velocity 5 radians per second. If the horizontal component of earth's magnetic field is $0.3 \times 10^{-4}T$, then the e.m.f. developed between the two ends of the conductor is

asked Nov 5, 2018 by pady_1

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In a LCR circuit capacitance is changed from C to 2C. For the resonant frequency to remain unchanged, the inductance should be changed from L to

asked Nov 5, 2018 by pady_1

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In a uniform magetic field of induction B a wire in the form of semicircle of radius r rotates about the diameter of the circle with angular frequency $\omega$. The axis of rotation is perpendicular to the field. If the total resistance of the circuit is R the mean power generated per period of rotation is

asked Nov 5, 2018 by pady_1

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A coil having n turns and resistance $4 R \Omega$. This combination is moved in time t seconds from a magnetic field $W_1$ weber to $W_2$ weber. The induced current in the circuit is

asked Nov 5, 2018 by pady_1

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In an LCR series a.c. circuit, the voltage across each of the components, L, C and R is 50 V. The voltage across the LC combination will be

asked Nov 5, 2018 by pady_1

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The materials suitable for making electromagnets should have

asked Nov 5, 2018 by pady_1

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The length of a magnet is large compared to its width and breadth. The time period of its width and breadth. The time period of its oscillation in a vibration magnetometer is 2 s. The magnet is cut along its length into three equal parts and three parts are then placed on each other with their like poles together. The time period of this combination will be

asked Nov 5, 2018 by pady_1

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Two long conductors, separated by a distance $d$ carry current $I_1$ and $I_2$ in the same direction. They exert a force $F$ on each other. Now the current in one of them increased to two times and its direction reversed. The distance is also increased to $3d$. The new value of the force between them is

asked Nov 5, 2018 by pady_1

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The magnetic field due to a current carrying circular loop of radius 3 cm at a point on the axis at a distance of 4 cm from the centre is 54 $\mu$T. What will be its value at the centre of the loop ?

asked Nov 5, 2018 by pady_1

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A long wire carries a steady current. It is bent into a circle of one turn and the magnetic field at the centre of the coil is B. It is then bent into a circular loop of n turns. The magnetic field at the centre of the coil will be

asked Nov 5, 2018 by pady_1

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A current I ampere flows along an infinitely long straight thin walled tube, then the magnetic induction at any point inside the tube is

asked Nov 5, 2018 by pady_1

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The electrochemical equivlent of a metal is $3.3 \times 10^{-7}$ kg per coulomb. The mass of the metal liberated at the cathode when a 3A current is passed for 2 seconds will be

asked Nov 5, 2018 by pady_1

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The thermo emf of a thermocouple varies with the temperature $\theta$ of the hot junction as $E= a \theta + b \theta^2$ in volts where the ratio $a/b$ is $700^{\circ}C$. If the cold junction is kept at $0^{\circ}C$, then the neutral temperature is

asked Nov 5, 2018 by pady_1

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