A spring has a natural length of 25 meters. A force of 12 newtons is required to stretch the spring to a length of 30 meters. How much work is done to stretch the spring from it's natural length to 40 meters?
-I forgot to add the 40 meters part to my other question
here is what i have done and i cant figure out what to do:
F = ks
12 = k(15)
12/15 = k
integrating from 0 to 15
12/15 sds
12/15 x S squared / 2 from 0 to 15
i end up with 225/2. the answer is supposed to be 270 and i dont understand why i cant do this, please help. thank you