Q 11-03-057JEE MainJEE Main 2025 (29 Jan, Shift 1)Medium
The maximum speed of a boat in still water is $27\ \text{km/h}$. Now this boat is moving downstream in a river flowing at $9\ \text{km/h}$. A man in the boat throws a ball vertically upwards with a speed of $10\ \text{m/s}$. The range of the ball as observed by an observer at rest on the river bank is ______ cm. (Take $g = 10\ \text{m/s}^2$)
Numerical value type. Enter your answer.
Answer: 2000
Moving downstream at full speed, the boat's speed relative to the bank is $27 + 9 = 36\ \text{km/h} = 10\ \text{m/s}$. The ball shares this horizontal velocity.
Time of flight: $T = \dfrac{2\times10}{10} = 2\ \text{s}$.
Range seen from the bank: $10\times2 = 20\ \text{m} = 2000\ \text{cm}$.
Solution by Sreeraj P, M.Sc Physics