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Saturday, 31 October

JEE Main 2020 · PhysicsMultiple choiceSingle correctMediumMulti-step

JEE Main 5 September 2020, Shift 1, Physics Q3

Question 3 of 75 in this shift, Physics question 3 of 25.

A helicopter rises from rest on the ground vertically upwards with a constant acceleration g. A food packet is dropped from the helicopter when it is at a height h. The time taken by the packet to reach the ground is close to [g is the acceleration due to gravity] :
  1. (1)t=1.8hgt = 1.8\sqrt{\frac{h}{g}}
  2. (2)t=2h3gt = \sqrt{\frac{2h}{3g}}
  3. (3)t=3.4(hg)t = 3.4\sqrt{\left(\frac{h}{g}\right)}Official answer
  4. (4)t=23(hg)t = \frac{2}{3}\sqrt{\left(\frac{h}{g}\right)}

Official answer

Option 3

NTA final key (Sep 2020).

Chapter
Motion in a Straight Line
Topic
Kinematics in 1D
Idea tested
Dropping Objects from Moving Frames

Same idea in other shifts

Asked 3× in all
  1. 8 Apr 2026, Shift 2 · Q29A gas balloon is going up with a constant velocity of 10 m/s. When this balloon reached a height of 75 m, a stone is dropped from it and…EasySingle correct
  2. 25 Jul 2021, Shift 2 · Q2A balloon was moving upwards with a uniform velocity of 10 m/s. An object of finite mass is dropped from the balloon when it was at a…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.