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Saturday, 31 October

JEE Main 2021 · PhysicsNumerical answerNumerical valueMediumMulti-step

JEE Main 27 August 2021, Shift 2, Physics Q23

Question 23 of 90 in this shift, Physics question 23 of 30, Section B.

A 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 length of the pendulum is 0.5 m and mass of the bob is 1 kg. The minimum value of v=v= __________ m/s so that the pendulum describes a circle. (Assume the string to be inextensible and g=10 m/s2g=10\ \mathrm{m/s^2})

The figure, in words

A pendulum string hangs vertically from a fixed point with a 1 kg bob at its lower end; the string length is marked 0.5 m. A 10 g bullet to the left of the bob moves horizontally to the right with velocity v towards the bob.

Official answer

400

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
  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. 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
  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.