Question

A stone is projected from the ground with velocity 50 m/s at an angle of ${30}^0$. It crosses a wall after 3 sec. How far beyond the wall the stone will strike the ground $(g=10m/se{c}^2)$

• A. 90.2 m
• B. 89.6 m
• C. 86.6 m
• D. 70.2 m

Answer 1

The correct option is C 86.6 m

Total time of flight = $\frac{2usin\theta }{g}=\frac{2\times 50\times 1}{2\times 10}=5s$
Time to cross the wall = 3 sec (given)
Time in air after crossing the wall = (5 – 3) = 2 sec
$\therefore$ Distance travelled beyond the wall = $\left(ucos\theta \right)t$

= $50\times \frac{\sqrt{3}}{2}\times 2$ = 86.6 m