Multiple choice general knowledge math & puzzles

In the comic’s nakshatra, I.G rajan is hanging by a rope tied to his waist and is unconscious. He is hanging at top of the building which is 100 meter high. The height of I.G rajan is 1.75 meters. Dhruv has to save him. Dhruv is 30 meter away from the base of building and is in perfect straight line with fall of I.G rajan. Dhruv notices a cart of sand that can break I.G rajan fall and thus can in turn save him. How much time Dhruv has in total to react? Take G=9.825 unit

  1. 5 sec

  2. 4.4 sec

  3. 3 sec

  4. 2 sec
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

For free fall from height h: h = ½gt². With h = 100m and g = 9.825 m/s²: t = √(2h/g) = √(200/9.825) = √20.36 ≈ 4.51 seconds. Option B (4.4s) is the closest approximation - the slight difference comes from rounding in intermediate steps.

AI explanation

The fall distance to react is the building height minus the person's own height, since he needs to be caught before his body (not just a point) reaches the ground: 100 - 1.75 ≈ 98.25 m. Using free-fall time t = √(2h/g) with g = 9.825, t = √(2×98.25/9.825) = √20 ≈ 4.47 s, which rounds to the 4.4 s option — this is the total time Dhruv has to act.

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