Four masses (each of `m`) are placed at the vertices of a regular pyramid (triangular base) of side 'a'. Find the work done by the system while taking them apart so that they form the pyramid of side '2a'.

Answer

`-(3Gm^(2))/(a)`

Explanation

External work done `= Delta U`
`= U_(f )-U_(i)=-(6Gm^(2))/(2a)-(-(6Gm^(2))/(a))=+(3Gm^(2))/(a)`
work done by system `= - (3Gm^(2))/(a)`