Q 11-02-064JEE MainJEE Main 2024 (27 Jan, Shift 2)Medium
A body falling under gravity covers two points A and B separated by $80\ \text{m}$ in $2\ \text{s}$. The distance of upper point A from the starting point is ______ m. (Use $g = 10\ \text{m s}^{-2}$)
Numerical value type. Enter your answer.
Answer: 45
Let the speed at A be $u$. From A to B:
$$80 = 2u + \frac12(10)(2)^2 \;\Rightarrow\; u = 30\ \text{m s}^{-1}$$
The body starts from rest, so
$$h_A = \frac{u^2}{2g} = \frac{900}{20} = 45\ \text{m}$$
Solution by Sreeraj P, M.Sc Physics