Question

The potential energy of $4$ -particles each of mass $1kg$ placed at the four vertices of a square of side length $1m$ is

• A. $+4.0G$
• B. $-7.5G$
• C. $-5.4G$
• D. $+6.3G$

Answer 1

Answer: (C)

Here, $AB=BC=CD=DA=1m$

$BD=AC$
$=\sqrt{1^2+1^2}$
$=\sqrt{2}m$
Total potential energy
$+\left[\frac{-G\times 1\times 1}{DA}\right]+\left[\frac{-G\times 1\times 1}{BD}\right]+\left[\frac{-G\times 1\times 1}{AC}\right]$
$=4\times \left[\frac{-G\times 1\times 1}{1}\right]+2\left[\frac{-G\times 1\times 1}{\sqrt{2}}\right]$
$=-5.4G$