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Saturday, 31 October

JEE Main 2021 · PhysicsNumerical answerNumerical valueMediumCalculation

JEE Main 4 August 2021, Shift 2, Physics Q24

Question 24 of 90 in this shift, Physics question 24 of 30, Section B.

A particle of mass 1 kg is projected at t = 0 from a point ‘O’ on the ground with a speed ‘u’ at an angle 45°45° to the horizontal. The magnitude of angular momentum of the particle about ‘O’ at time ug\frac{u}{g} is given by 7u3ag\frac{7u^3}{ag}. Then the value of a is _________. (Take 12=0.7\frac{1}{\sqrt{2}}=0.7 and g=10 m/s2g=10\,m/s^2)

The figure, in words

Axes: y axis (vertical, arrow up) and x axis (horizontal, arrow right) meeting at O. A solid arrow from O points up and to the right, with the angle between it and the x axis marked 45°. A dashed arc from O rises and comes back down to the x axis further right.

Official answer

20

NTA final key.

Chapter
System of Particles and Rotational Motion
Topic
Angular Momentum
Idea tested
Angular Momentum of a Projectile

Same topic in other shifts

All Angular Momentum questions
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  2. 4 Apr 2025, Shift 2 · Q50A solid sphere with uniform density and radius R is rotating initially with constant angular velocity (ω1)(\omega_1) about its diameter.…MediumNumerical value
  3. 8 Apr 2025, Shift 2 · Q47A thin solid disk of 1 kg is rotating along its diameter axis at the speed of 1800 rpm. By applying an external torque of 25π25\pi Nm for…MediumNumerical value
  4. 6 Apr 2024, Shift 1 · Q56If the radius of earth is reduced to three-fourth of its present value without change in its mass then value of duration of the day of…MediumNumerical value
  5. 8 Apr 2024, Shift 2 · Q35A thin circular disc of mass M and radius R is rotating in a horizontal plane about an axis passing through its centre and perpendicular…EasySingle correct
  6. 1 Feb 2024, Shift 1 · Q31The dimensional formula of angular impulse is :EasySingle correct

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.