So any of you good at physics out there.

My 16 year old has asked me for help with his homework which is WAY over my head :)

So this is is it.....can you explain as well so we can both understand

Ep=1/2 Kx2 .......the two should be above the x as in squared

Use the equation to find K were Ep = 398J x=0.045m

Thanks