Question

For a projectile thrown into air with a speed (v) the horizontal range is $\frac{\sqrt{3} v ^{2}}{2 \,g }$ and the vertical height is $\frac{ v ^{2}}{8\, g }$. The angle which the projectile makes with the horizontal initially is

• A. $15^{\circ}$
• B. $30^{\circ}$
• C. $45^{\circ}$
• D. $60^{\circ}$

Answer 1

Answer: (B)

$R =\frac{\sqrt{3} v ^{2}}{2 g }=\frac{ v ^{2} \sin 2 \theta}{ g }$
$\sin\, 2 \theta=\frac{\sqrt{3}}{2}$
$2 \theta=60^{\circ}$
$\theta=30^{\circ}$