Question

A river of salty water is flowing with a velocity $2m/s$, if the density of the water is $1.2g/cc$, then the kinetic energy of each cubic metre of water is

• A. $2.4J$
• B. $24J$
• C. $2.4kJ$
• D. $4.8kJ$

Answer 1

Answer: (C)

$2.4kJ$

Given, velocity of river, $\left(v\right)=2m/s$
Density of water, $\rho =1.2g/cc$
Mass of each cubic metre:
$m=\frac{1.2\times {10}^{-3}}{{10}^{-2\left(3^{\prime }\right)}}=1.2\times {10}^{3}kg$
$\therefore$ Kinetic energy $=\frac{1}{2}m{v}^2$
$=\frac{1}{2}\times 1.2\times {10}^3\times {\left(2\right)}^2$
$=2.4\times {10}^{3}J=2.4kJ$