JEE Mains 2021 physics questions with solutions

Showing 1–10 of 65 questions

• NumericmediumRotational Motionangular impulse in pure rotation and rotational collision

  A rod of mass M and length L lies on a horizontal frictionless surface. A particle of mass m moving perpendicular to the rod with speed u strikes one end elastically and comes to rest. If m/M = 1/x, find x.

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• NumericmediumRotational Motionrotational constrain motion

  Two wheels P and Q are connected by a belt. Radius of P is three times radius of Q. If both wheels have the same rotational kinetic energy and I₁/I₂ = x:1, find x.

  

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• MCQmediumsemiconductor

  Statement-I: To get a steady dc output from the pulsating voltage received from a full wave rectifier we can connect a capacitor across the output parallel to the load Rₗ. Statement-II : To get a steady dc output from the pulsating voltage received from a full wave rectifier we can connect an inductor in series with Rₗ. In the light of the above statements, choose the most appropriate answer from the options given below:

  Options

  • Option A

    Statement I is true, but Statement II is false.

  • Option B

    Statement I is false, but Statement II is true.

  • Option C

    Both Statement I and Statement II are false.

  • Option D

    Both Statement I and Statement II are true.

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• NumericmediumWork , Power and Energyvertical circular motion

  A small block slides from rest from the top of a smooth hemisphere of radius R=3 m. Find the height h (m) above the ground at which it loses contact with the hemisphere.

  

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• MCQmediumNewtons law of motion and Frictiontypes of friction and problem based on it

  A block of mass m slides on a horizontal floor while a force F is applied at angle θ above the horizontal. The coefficient of kinetic friction is μₖ. The acceleration a is:

  

  Options

  • Option A

    -(F/m)cosθ - μₖ(g - (F/m)sinθ)

  • Option B

    (F/m)cosθ - μₖ(g - (F/m)sinθ)

  • Option C

    (F/m)cosθ - μₖ(g + (F/m)sinθ)

  • Option D

    (F/m)cosθ + μₖ(g - (F/m)sinθ)

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• MCQmediumWork , Power and Energykinetic enegy and work engery theorem

  A body of mass 'm' dropped from a height 'h' reaches the ground with a speed of 0.8√𝑔ℎ. The value of work done by the air-friction is :

  Options

  • Option A

    –0.68 mgh

  • Option B

    mgh

  • Option C

    1.64 mgh

  • Option D

    0.64 mgh

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• MCQmediumRotational Motiontorque and rotational equilibrium

  A solid cylinder of mass m is wrapped with an inextensible light string and, is placed on a rough inclined plane as shown in the figure. The frictional force acting between the cylinder and the inclined plane is: [The coefficient of static friction, μs, is 0.4]

  

  Options

  • Option A

    7/2mg

  • Option B

    5mg

  • Option C

    mg/5 60°

  • Option D

    0

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• MCQmediumSimple Harmonic Motion

  A mass of 5 kg is connected to a spring. The potential energy curve of the simple harmonic motion executed by the system is shown in the figure. A simple pendulum of length 4 m has the same period of oscillation as the spring system. What is the value of acceleration due to gravity on the planet where these experiments are performed?

  

  Options

  • Option A

    10 m s⁻²

  • Option B

    5 m s⁻²

  • Option C

    4 m s⁻²

  • Option D

    9.8 m s⁻²

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• MCQmediumProperties of solid and fluid

  Two blocks of masses 3 kg and 5 kg are connected by a metal wire over a smooth pulley. The breaking stress of the metal is (24/π)×10² N m⁻². Find the minimum wire radius. Take g=10 m s⁻².

  Options

  • Option A

    125 cm

  • Option B

    1250 cm

  • Option C

    12.5 cm

  • Option D

    1.25 cm

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• MCQmediumPhotoelectric effect and dual nature of matter

  A particle has kinetic energy E and de Broglie wavelength λ. How much additional energy must be supplied so that its wavelength becomes 75% of its initial value?

  Options

  • Option A

    E/9

  • Option B

    7E/9

  • Option C

    5E/9

  • Option D

    16E/9

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