Question

Water from a hose pipe of radius $5$cm strikes a wall normally at a speed of $5$ $m{s}^{-1}$. The force exerted on the wall in newton is:

• A. $13.5\pi$
• B. $6.25\pi$
• C. $62.5\pi$
• D. $27\pi$
• E. $125\pi$

Answer 1

The correct option is C $62.5\pi$

Given, Radius of hose pipe(r)$=5$cm
$=5\times {10}^{-2}$m
Speed of water(v)$=5m{s}^{-1}$
We know that, $F=A{v}^2\rho$, where $\rho =1000kg/m^3$ for water
$F=\pi r^2{v}^2\rho$
$F=\pi (5\times {10}^{-2}{)}^2(5{)}^2\times 1000$
$F=62.5\pi$.