Question

Gravitational field is uniform and the gravitational potential difference between surface of a planet and a point $100m$ above is $50J/Kg$. The work done in moving a man $5kg$ from surface to a point $10m$ above is :

• A. $5J$
• B. $25J$
• C. $2.5J$
• D. $50J$

Answer 1

The correct option is B $25J$

Given, Gravitational Field is uniform. Since
$V=\int Edr$
$V=E\Delta r$
Hence,
$E=\Delta V/\Delta r$
Thus,
$E=50/100=0.5$
Work done in moving a 5 kg from the surface to a point 10 m above is

$W=mEd$

$W=0.5\times 5\times 10=25J$
Hence, option B is correct.