Question

A boy weighing $25kgf$ climbs up from the first floor at a height $3m$ above the ground to the third floor at a height $9m$ above the ground. What will be the increase in his gravitational potential energy? (Take $g=10Nk{g}^{-1}$)

• A. $1500J$
• B. $0J$
• C. $150J$
• D. $2250J$

Answer 1

The correct option is A $1500J$

$P.E=m\times g\times h$
In first case that is in 3 m
$P.E=25\times 10\times 3=750J$
In the second case that is 9 m
$P.E=25\times 10\times 9=2250J$
Hence the difference is $2250-750=1500J$.