hooke's law says the spring force = -kx but the work done in stretching a spring = 1/2 kx^2 isnt work = Fd? so using W=Fd and F=-kx (hooke's law) shouldnt the work come out to: W = -kx^2? (arent d and x the same? both are distance stretched) where does the 1/2 come from in the equation 1/2kx^2? can someone help clarify the difference and when to use each equation. thanks.