Question

Water from a house pipe of radius $5\, cm$ strikes a wall normally at a speed of $5\, ms^{-1}$. The force exerted on the wall in netwton is

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

Answer 1

Answer: (C)

Given, Radius of hose pipe $(r)=5\, cm$
$=5 \times 10^{-2}\, m$
Speed of water $(v)=5\, ms ^{-1}$ We know that,
$F=A v^{2} \rho $
$F=\pi r^{2} v^{2} \rho $
$F=\pi\left(5 \times 10^{-2}\right)^{2}(5)^{2} \times 1000$
$F=62.5\, \pi$