Question

The speed with which a body is projected inside a tunnel such that it just grazes the top is 40 $m{s}^{-1}$ and the range is 80$\sqrt{3}$ m. Find the
height of tunnel.

• A. 5 m
• B. 10 m
• C. 15 m
• D. 20 m

Answer 1

The correct option is D 20 m

$R=\frac{u^{2}sin2\theta }{g}=80\sqrt{3}\Rightarrow \frac{{40}^{2}sin2\theta }{10}=80\sqrt{3}\Rightarrow \theta ={30}^{0}H=\frac{u^{2}si{n}^2\theta }{2g}=20m$