Question

A boy playing on the roof of a $10$ m high building throws a ball with a speed of $10$ m s${}^{-1}$ at an angle of ${30}^o$ with the horizontal. How far from the throwing point will the ball he at the height of $10$ m from the ground ($g=10m{s}^{-2},sin{30}^o=\frac{1}{2},cos{30}^o=\frac{\sqrt{3}}{2}).$

• A. 8.6m
• B. 9.6 m
  
• C. 10.6 m
  
• D. 11.6 m
  

Answer 1

The correct option is A 8.6m

We have to simply calculate the range of projectile.

$R=\frac{u^2\sin 2\theta }{g}$

$=\frac{\left(10{)}^2\sin \right(2\times {30}^o)}{10}$

$=5\sqrt{3}=8.66m$