Question

The gravitational potential difference between the surface of a planet and a point $20m$ above the surface is $2$ joule/kgs. If the gravitational field is uniform, then the work done in carrying a $5$ kg body to a height of $4m$ above the surface is

• A. $2J$
• B. $20J$
• C. $40J$
• D. $10J$

Answer 1

The correct option is A $2J$

For uniform gravitational field,
$g=-\frac{V}{r}=-\frac{-2}{20}=\frac{1}{10}m{s}^{-2}$
Now, $W=mgh=5\times \frac{1}{10}\times 4=2J$