Confused about Spring PE Formula: Hooke's Law vs. 1/2 kx^2

[Prone17]

when attempting questions with springs involved, i get confused with the spring PE formula.
i know its a simple formula but i don't get the correct answers

i know hooke's law is E = -kx
but in class i was given the formula E = 1/2 kx^2

is there a different time to use each of these equations, or is one incorrect, or...?

thanks for your help

 

[zorro]

Hooke's Law is F = -kx where F stands for force

 

[tiny-tim]

Welcome to PF!

Hi Prone17! Welcome to PF!

Yes, one is force and the other is energy.

You choose between them in the same way that you choose whether to use F = ma or KE = 1/2 mv².