Question

$20$ litre of water per second is lifted from well through $45m$ and delivered with a velocity of $10m/s$, then the power of the motor is:

Answer 1

Mass water litre per second $=20$ litre

depth of well $=45m$.

Velocity of water $=10m/s$

Power $=$ Force $\times$ velocity

Weight of $20$ litre of water $=20\times 1000g$

$=20kg$

Now, $mgh=\left(20\right)\left(g\right)\left(45\right)$

$=\left(200\right)\left(45\right)=9000$

Now, work done by the motor $=$ Force $\times$ distant

$=f\times 45$

$\therefore 9000=f\times 45$

$f=200$ & power $=f\times velocity$

$=200\times 10=2kW$