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Saturday, 31 October

JEE Main 2021 · PhysicsNumerical answerNumerical valueMediumCalculation

JEE Main 3 August 2021, Shift 1, Physics Q21

Question 21 of 90 in this shift, Physics question 21 of 30, Section B.

The 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 the top of the loop and goes around the loop without falling off the track. The minimum value of ‘hh' required for a successful looping is _________ cmcm. (Ignore friction)

The figure, in words

A circular loop track with a vertical radius line from its centre to the top labelled R, joined to a horizontal ground line at the bottom that continues to the right and then rises along a straight inclined line to a platform at the upper right. A small car (truck-like outline) stands on the platform with a leftward arrow beside it. A horizontal dashed line runs from the top of the loop to the right; a second short dashed line at the car's level; between them an upward arrow labelled h.

Official answer

380

NTA final key.

Chapter
Work, Energy and Power
Topic
Circular Motion
Idea tested
Vertical Circular Motion

Same idea in other shifts

Asked 7× in all
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  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. 4 Aug 2021, Shift 2 · Q25A 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…HardNumerical 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.