Q. A stone thrown upward with a speed $u$ from the top of the tower reaches the ground with a velocity $3u$. The height of the tower is
A) $3u^{2}/g$
B) $4u^{2}/g$
C) $6u^{2}/g$
D) $9u^{2}/g$
Explanation
(b) $v^{2} = u^{2} + 2gh \Rightarrow (3u)^{2} = ( - u)^{2} + 2gh \Rightarrow h = \frac{4u^{2}}{g}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.