Question

The gravitational potential difference between the surface of a planet and a point $10m$ above is $4.0Jk{g}^{-1}$. Assuming the gravitational field to be uniform, the work done in moving a $2.0kg$ mass from the surface of the planet to a height of $5.0m$ is

• A. $1.0J$
• B. $2.0J$
• C. $4.0J$
• D. $8.0J$

Answer 1

The correct option is C $4.0J$

$u\left(h\right)=mah$

$\frac{u\left(h\right)}{m}=ah=4J/Kg$

$a=\frac{4}{h}=\frac{4}{10}$

Workdone to move a height $5m$.

$⟹ma{h}_i=2\times \frac{4}{10}\times 5$

$=4J$