The elastic potential energy stored in the spring is 0.017J
When a spring is compressed, work is done against the restoring force which is set up in the spring. This work done is stored in the spring as its elastic potential energy.
The expression for elastic potential energy stored in a spring is given by,
[tex]E=\frac{1}{2} kx^2[/tex]
Here, k is the spring constant and x is the compression in the spring.
Substitute 0.12 m for x ans 2.3 n?m for k.
[tex]E=\frac{1}{2} kx^2\\ =\frac{1}{2}(2.3 N/m)(0.12 m)^2\\ =0.01656 J=0.017 J[/tex]
Thus the spring stores 0.017 J as its elastic potential energy when compressed by 0.12 m.