Question

From the top of a tower a stone is thrown up.It reaches the ground in 9sec .A second stone thrown down with the same speed reaches the ground in 4 sec.A third stone released fromrest reaches

Answer 1

answer : 6 sec

concept : when a stone is thrown up from a height and it reaches the ground in $t_1$ sec . again another stone from same the height is thrown down with the same speed , it reaches the ground in $t_2$.

then a third particle which is released from the same height , reaches the ground in $\bf{t=\sqrt{t_1\times t_1}}$

here given, $t_1=9sec$ and $t_2=4sec$

so, time taken to reach the ground by third stone , t = √(9 × 4) = √(36) = 6sec

hence, answer is 6sec.

also read : To understand derivation of formula. check below given link.

Let three balls 1, 2, and 3 are allowed to fall under gravity from the same

height. Ball 1 is thrown vertically upward w...

https://brainly.in/question/9222818