Question

The gravitational potential difference between the surface of planet and a point 20 m above its surface is $2Jk{g}^{-1}$ If the gravitational field over this range is uniform, then the work done to raise the body of 5 kg from the surface to a height of 4 m is:

• A. 1 J
• B. 2 J
• C. 4 J
• D. 8 J

Answer 1

The correct option is B 2 J

Here,

$m=5kg$

$V=2J/Kg$

$h_2-h_1=20$m

$V=g(h_2-h_1)=2$

$g\left(20\right)=2$

$\Rightarrow g=0.1m{s}^{-2}$

Now work done in rising a mass of $5$ kg by $4$ m will be

$W=Mgh$

$\Rightarrow W=0.1\times 5\times 4$

$\Rightarrow W=2J$

Work done will be $2$ Joule.