Question

A stone is projected from the ground with velocity $50\, m / s$ at an angle $30^{\circ}$ with horizontal. It crosses a wall after $3\, s$. How far beyond the wall the stone will strike the ground? $\left(g=10\, m / s ^{2}\right)$

• A. $90.2\, m$
• B. $12.5\, m$
• C. $86.5\, m$
• D. $125 \sqrt{3} m$

Answer 1

Answer: (C)

Time, $T=\frac{2 u \sin \theta}{g}=\frac{2 \times 50 \times \sin 30^{\circ}}{10}$
$=\frac{2 \times 50 \times \frac{1}{2}}{10}=5\, s$ Time spent after crossing the wall,
$t_{2}=5-3=2\, s$
$\therefore$ Distance,
$x_{2}=u \cos \theta \times 2=50 \times \cos 30^{\circ} \times 2$
$=86.5\, m$