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Saturday, 31 October

JEE Main 2021 · PhysicsNumerical answerNumerical valueHardMulti-step

JEE Main 4 August 2021, Shift 2, Physics Q25

Question 25 of 90 in this shift, Physics question 25 of 30, Section B.

A small solid spherical marble of mass M and radius 5 cm rolls along loop track without slipping. The height above the base, from where it has to start rolling down incline such that the sphere just completes the vertical circular loop of radius 25 cm is _________ cm. (g = 10 m/s2^2)

The figure, in words

A curved track descends from a point at height h (h marked with a vertical dashed line down to a horizontal dashed base line) and joins the bottom of a vertical circular loop; the loop’s radius is marked 25.

Official answer

54

NTA final key.

Chapter
System of Particles and Rotational Motion
Topic
Circular Motion
Idea tested
Vertical Circular Motion

Same idea in other shifts

Asked 7× in all
  1. 24 Jun 2022, Shift 2 · Q33A stone of mass m, tied to a string is being whirled in a vertical circle with a uniform speed. The tension in the string isEasySingle correct
  2. 26 Jun 2022, Shift 1 · Q34A ball is released from rest from point P of a smooth semi-spherical vessel as shown in figure. The ratio of the centripetal force and…HardDiagram basedHas a figure
  3. 27 Jun 2022, Shift 2 · Q35A stone tide to a string of length L is whirled in a vertical circle with the other end of the string at the centre. At a certain instant…MediumSingle correct
  4. 3 Aug 2021, Shift 1 · Q21The given figure shows a loop-the-loop track having radius 760 cmcm. A car without engine starts from a platform at a distance ‘hh' above…MediumNumerical valueHas a figure
  5. 27 Aug 2021, Shift 2 · Q23A bullet of 10 g, moving with velocity vv, collides head-on with the stationary bob of a pendulum and recoils with velocity 100 m/s. The…MediumNumerical valueHas a figure
  6. 25 Feb 2021, Shift 1 · Q24A small bob tied at one end of a thin string of length 1 m is describing a vertical circle so that the maximum and minimum tension in the…MediumNumerical value

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.