**Question **: A ball is thrown vertically upwards. It was observed at a height ℎ twice with a time interval ∆𝑡. The initial velocity of the ball is

(A) \sqrt{8gh+g^{2}\left( \Delta t\right) ^{2}}

(B) \sqrt{8gn+\left( \dfrac{g\Delta t}{2}\right) ^{2}}

(C) \dfrac{1}{2}\sqrt{8gh+g^{2}\left( \Delta t\right) ^{2}}

(D) \sqrt{8gh+4g^{2}\left( \Delta t^{2}\right) }

**Answer** : option (c)

**Solution** :

*Related*