Question

Gravitational potential difference between a point on the surface of a planet and point $10m$ above is $4J/kg$ considering the gravitational field to be uniform,how much work is done in moving a mass of $2kg$ from the surface to a point $5m$ above the surface ?

• A. $40J$
• B. $45J$
• C. $6J$
• D. $73J$

Answer 1

The correct option is B $45J$

$v_2-v_1=4Jkg$
$x_2-x_1=10m$
potential gradient =$\frac{v_2-v_1}{x_2-x_1}$
How is because it is given the gravitational field is uniform
$\therefore \frac{\Delta h}{\Delta x}=\frac{4}{10}$
for $5m$ workdone =$mt(\frac{\Delta v}{\Delta x}\times (5\left)\right)$
$=2\times \frac{4}{5}\times 5$
$=45$