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Saturday, 31 October

JEE Main 2021 · PhysicsMultiple choiceSingle correctEasyApplication

JEE Main 26 February 2021, Shift 2, Physics Q9

Question 9 of 90 in this shift, Physics question 9 of 30, Section A.

The trajectory of a projectile in a vertical plane is y=αx−βx2y = \alpha x - \beta x^2, where α\alpha and β\beta are constants and x & y are respectively the horizontal and vertical distances of the projectile from the point of projection. The angle of projection θ\theta and the maximum height attained H are respectively given by :
  1. (1)tan⁡−1β,α22β\tan^{-1}\beta, \frac{\alpha^2}{2\beta}
  2. (2)tan⁡−1(βα),α2β\tan^{-1}\left(\frac{\beta}{\alpha}\right), \frac{\alpha^2}{\beta}
  3. (3)tan⁡−1α,α24β\tan^{-1}\alpha, \frac{\alpha^2}{4\beta}Official answer
  4. (4)tan⁡−1α,4α2β\tan^{-1}\alpha, \frac{4\alpha^2}{\beta}

Official answer

Option 3

NTA final key.

Chapter
Motion in a Plane
Topic
Projectile Motion
Idea tested
Trajectory Equation Application

Same idea in other shifts

Asked 5× in all
  1. 8 Apr 2023, Shift 2 · Q39The trajectory of projectile, projected from the ground is given by y=x−x220y = x - \frac{x^2}{20}. Where xx and yy are measured in meter. The…MediumSingle correct
  2. 26 Jul 2022, Shift 1 · Q51If the initial velocity in horizontal direction of a projectile is unit vector i^\hat{i} and the equation of trajectory is y=5x(1−x)y = 5x(1-x).…MediumNumerical value
  3. 27 Jul 2022, Shift 2 · Q32A body of mass 10 kg is projected at an angle of 45∘45^\circ with the horizontal. The trajectory of the body is observed to pass through a…MediumSingle correct
  4. 3 Aug 2021, Shift 2 · Q8A projectile is thrown with initial velocity of (3i^+4j^) m/s(3\hat{i}+4\hat{j})\ \mathrm{m/s}. Here 'i^\hat{i}' is along the horizontal direction…MediumSingle 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. Lumi analyses 108 of the 174 JEE Main shifts held from 2017 to 2026.