Is energy profile of a spring asymmetric with +x and -x?

[Aliasa]

Homework Statement

[/B]

The problem is with part b(ii). This is an A level question so only elementary concepts are to be used.

Homework Equations

$$E = \frac{1}{2}kx^2 $$

The Attempt at a Solution

EPE should be max at 0, 0.4, 0.8 since E is a function of $x^2$. However, mark scheme only accepts 0 and 0.8 only. It is my understanding that energy profile of a spring is symmetric under compression and expansion, but if so, why is 0.4 not acceptable?

 

[TSny]

When the mass is hanging at rest as in part (a), does the spring have any elastic potential energy?

 

[Aliasa]

Ah, right, I missed that. Thanks!