The work done in extending a spring by `x_0` is `W_0`. Find the work done in further extension `x_0`.

Explanation

Force, `F=F_(s)=kx`
`W_(0)=int F dx=int_(0)^(x_(0))kx dx=(kx_(0)^(2)



)/(2)`
Let W be the work done in extending a spring by `2x_(0)`.
`W=intF dx=int_(x_(0))^(2x_(0))kx dx`
`=(k)/(2)[(2x_(0))^(2)-x_(0)^(2)]=(3)/(2)k_(0)^(2)`
`(W)/(W_(0))=3impliesW=3W_(0)`