Question

$500litres$ of water is raised from a height $6m$ to $15m$. If density of water is $1kg{l}^{-1}$ then the change in its potential energy is_______. (take $g=10m{s}^{-2}$):

• A. $4\times {10}^{4}J$
• B. $6\times {10}^{4}J$
• C. $2\times {10}^{4}J$
• D. $4.5\times {10}^{4}J$

Answer 1

The correct option is D $4.5\times {10}^{4}J$

Given,
Volume of water$=500l$,
Acceleration due to gravity, $g=10m{s}^{-2}$,
Density of water $=1kglitr{e}^{-1}$,
Height $h_1=6m$
Height $h_2=15m$

Let, the mass of water be $m$
Mass of water, $m$= Volume of water$\times$density of water$=500\times 1=500kg$
Change in PE $=mg(h_2-h_1)=500\times 10\times (15-6)=4.5\times {10}^{4}J$
Therefore, the increase in potential energy will be $4.5\times {10}^{4}J$.