Question

A fire extinguishing hose pipe disposes watch at a speed of 10 m/s to put off fire on a building. Assuming safe distance from the building on ground is 5 m, What is the maximum height at which water strikes building?

• A. 1.75 m
• B. 2.5 m
• C. 3.75 m
• D. 4.75 m

Answer 1

The correct option is B 2.5 m

Range $R=5\times 2=10m$

$R=\frac{u^2\sin 2\theta }{g}$ where $u=10m/s$

$10=\frac{100\times \sin 2\theta }{10}$

$\sin 2\theta =1$

$\theta ={45}^{\circ }$

$H=\frac{u^2{\sin }^2\theta }{2g}=\frac{100\times \left(1/2\right)}{2\times 10}$

$=2.5m$