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Saturday, 31 October

JEE Main 2021 · PhysicsMultiple choiceDiagram basedMediumMulti-step

JEE Main 25 February 2021, Shift 2, Physics Q3

Question 3 of 90 in this shift, Physics question 3 of 30, Section A. NTA dropped this question from the final key; it is left out of every count on this site.

A sphere of radius ‘a’ and mass ‘m’ rolls along a horizontal plane with constant speed v0v_{0}. It encounters an inclined plane at angle θ\theta and climbs upward. Assuming that it rolls without slipping, how far up the sphere will travel ?

The figure, in words

A sphere (circle) of radius labelled a on a horizontal line, with an arrow to its right labelled v0; a right-triangle inclined plane to its right with angle theta marked at the bottom-left vertex where the incline meets the horizontal.
  1. (1)v022gsin⁡θ\frac{v_0^2}{2g\sin\theta}
  2. (2)v025gsin⁡θ\frac{v_0^2}{5g\sin\theta}
  3. (3)10v027gsin⁡θ\frac{10v_0^2}{7g\sin\theta}
  4. (4)25v02gsin⁡θ\frac{2}{5}\frac{v_0^2}{g\sin\theta}

Official answer

Dropped by NTA (marks given to all)

NTA final key: NTA final key 'D' = question dropped.

Chapter
Work, Energy and Power
Topic
Work and Kinetic Energy
Idea tested
Conservation of Mechanical Energy

Same idea in other shifts

Asked 7× in all
  1. 3 Apr 2025, Shift 1 · Q28A particle is released from height S above the surface of the earth. At certain height its kinetic energy is three times its potential…EasySingle correct
  2. 30 Jan 2024, Shift 1 · Q35A particle is placed at the point A of a frictionless track ABC as shown in figure. It is gently pushed towards right. The speed of the…EasyDiagram basedHas a figure
  3. 27 Jun 2022, Shift 2 · Q52A rolling wheel of 12 kg is on an inclined plane at position P and connected to a mass of 3 kg through a string of fixed length and pulley…HardNumerical valueHas a figure
  4. 28 Jun 2022, Shift 1 · Q51A pendulum is suspended by a string of length 250 cm. The mass of the bob of the pendulum is 200 g. The bob is pulled aside until the…EasyNumerical valueHas a figure
  5. 26 Aug 2021, Shift 1 · Q21A uniform chain of length 3 meter and mass 3 kg overhangs a smooth table with 2 meter laying on the table. If k is the kinetic energy of…MediumNumerical value
  6. 26 Feb 2021, Shift 2 · Q8A cord is wound round the circumference of wheel of radius r. The axis of the wheel is horizontal and the moment of inertia about it is I.…MediumSingle correct
  7. 18 Mar 2021, Shift 1 · Q24As shown in the figure, a particle of mass 10 kg is placed at a point A. When the particle is slightly displaced to its right, it starts…EasyNumerical valueHas a figure

Question text from the official JEE Main paper published by NTA; answer from the final answer key. Chapter, topic and idea tags, difficulty and skill are Lumi’s. This question needs a figure we do not reproduce; it is described in words above. Lumi analyses 108 of the 174 JEE Main shifts held from 2017 to 2026.