[tex]energy = elastic \: potential[/tex]
[tex]4 = \frac{1}{2} kx {}^{2} [/tex]
[tex]4 = \frac{1}{2} (2500)x {}^{2} [/tex]
[tex]4 = 1250x {}^{2} [/tex]
[tex]x {}^{2} = \frac{4}{1250} = 0.0032 \: meters[/tex]
[tex]x = \sqrt{0.0032} = 0.05657 \: meters[/tex]