Answer:
37.4 cm
Explanation:
The force that the spring exterts when stretched is:
[tex]F = -k (x-x_0)[/tex]
Where x_0 is the relaxed length and k = 680 N/m
If a steady force of 133 N is applied when pulling the spring and elonged to a total length of 57 cm, the spring must extert the same force, but in the opposite direction, that is:
[tex]-133 N = -680 N/m (0.57m -x_0)[/tex]
Solving for x_0
[tex]x_0 = 0.57 m -\frac{133}{680} m = 0.57 - 0.196 m = 0.374 m[/tex]