(Figure 5.11) shows two positions `A and B` at the same height `h` above the ground. If the maximum height os the projectile is `H`, then determine the time `t` elapses between the positions `A and B` in terms of `H`.
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Explanation

Let `T` be the time of flight. We can now wire
`T = (2 u sin theta)/(g)`
`T^2 = (4 u^2 sin^2 theta)/(g^2) = (8)/(g) ((u^2 sin^2 theta)/(g)) = (8 H)/(g)`
Hence, we can write in similar way, `t^2 = (8(H - h))/(g)`
Thus, `t = sqrt((8)/(g) (H - h))`.