Question

The initial speed of a projectile fired from ground is $u$. At the highest point during its motion, the speed of projectile is $\frac{\sqrt{3}}{2} u$. The time of flight of the projectile is :

• A. $\frac{2 u }{ g }$
• B. $\frac{ u }{2 g }$
• C. $\frac{ u }{ g }$
• D. $\frac{\sqrt{3} u}{g}$

Answer 1

Answer: (C)

$ u \cos \theta=\frac{\sqrt{3} u }{2} $
$\Rightarrow \cos \theta=\frac{\sqrt{3}}{2}$
$\Rightarrow \theta=30^{\circ} $
$ T =\frac{2 u \sin 30^{\circ}}{ g }=\frac{ u }{ g }$