A3.15 kg fish is attached to the lower end of a vertical spring that has negligible mass and force constant 855 n/m . the spring initially is neither stretched nor compressed. the fish is released from rest.

In this item, we are asked to determine the length at which the spring will be stretched given that a fish is attached to one of its end. To answer this, first, we must calculate for the weight of the fish.
                              Weight = (3.15 kg)(9.8 m/s²)
                              Weight = 30.87 N
Then, divide the calculated weight by the given force constant to determine the length.
                            Length = (30.87 N)/(855 N/m) = 0.036 m

Centrapedial force is the answer

No it doesnt because it can be any number.