Q 11-02-034NEETJEE MainMedium
A juggler throws balls vertically upward, one every $0.5$ s, all with the same speed. Each ball reaches its highest point just as the next ball is thrown. The maximum height reached by each ball is ($g = 10\ \text{m/s}^2$)
Answer: (C) $1.25$ m
Concept. The time to reach the top, $\dfrac{u}{g}$, equals the interval between throws; then $H = \dfrac{u^2}{2g}$.
Step 1. Speed. $\dfrac{u}{10} = 0.5 \Rightarrow u = 5$ m/s.
Step 2. Height. $H = \dfrac{25}{20} = 1.25$ m.
Answer. $1.25$ m (Option C).
Solution by Sreeraj P, M.Sc Physics