JEE Mains 2021 physics questions with solutions

Showing 1–10 of 65 questions

• NumericmediumCircular Motionkinematics of circular motion

  The angular speed of truck wheel is increased from 900 rpm to 2460 rpm in 26 seconds. The number of revolutions by the truck engine during this time is _______. (Assuming the acceleration to be uniform).

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• MCQmediumWork , Power and Energykinetic enegy and work engery theorem

  If the Kinetic energy of a moving body becomes four times its initial Kinetic energy, then the percentage change in its momentum will be :

  Options

  • Option A

    100%

  • Option B

    200%

  • Option C

    300%

  • Option D

    400%

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• NumericmediumWork , Power and Energyconservation of mechanical energy

  A ball of mass 4 kg, moving with a velocity of 10 m s⁻¹, collides with a spring of length 8 m and force constant 100 N m⁻¹. The length of the compressed spring is x m. The value of x, to the nearest integer, is_________.

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• MCQmediumProperties of solid and fluid

  In Millikan's oil drop experiment, what is viscous force acting on an uncharged drop of radius 2.0 × 10⁻⁵ m and density 1.2 × 10³ kg m⁻³? Take viscosity of liquid = 1.8 × 10⁻⁵ N s m⁻². (Neglect buoyancy due to air)

  Options

  • Option A

    3.8 × 10⁻¹¹ N

  • Option B

    3.9 × 10⁻¹⁰ N

  • Option C

    1.8 × 10⁻¹⁰ N

  • Option D

    5.8 × 10⁻¹⁰ N

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• 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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• 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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• NumericmediumWork , Power and Energyvertical circular motion

  A small bob tied at one end of a thin string of length 1m is describing a vertical circle so that the maximum and minimum tension in the string are in the ratio 5 : 1. The velocity of the bob at the highest position is _____ m/s. (Take g = 10 m/s²)

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• MCQmediumsemiconductor

  The shown logic circuit is equivalent to which of the four candidate circuits? Image

  Options

  • Option A

    Image 1

  • Option B

    Image 2

  • Option C

    Image 3

  • Option D

    Image 4

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• NumericmediumWork , Power and Energykinetic enegy and work engery theorem

  A spring gun of spring constant 100 N/m contains a 100 g ball. The spring is compressed by 0.05 m. The ball leaves the gun horizontally from height 2 m. Find the horizontal distance d (m) at which a box should be placed. (g=10 m/s²)

  

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• NumericmediumThermodynamics

  In 5 minutes, a body cools from 75°C to 65°C at room temperature of 25°C. The temperature of body at the end of next 5 minutes is to be determined°C.

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