It takes 3.78 J of work to stretch a Hooke’s-law

Question

spring 14.2 cm from its unstressed length.
How much the extra work is required to
stretch it an additional 11.2 cm?
Answer in units of J.

Answer 1

Now this is so similar to your last question that I hesitate to say aanything.
remember from the other one:
potential energy stored = (1/2) k x^2
so
3.78 Joules = .5 * k * (.142)^2
solve for k
now TOTAL work to get to 14.2 + 11.2 or 25.4
= .5 * k * (.254)^2 Joules
now subtract 3.78 from that

Answer 2

Oh!! I get it, I just had trouble finding out how to solve to get k, but then I realized you just have to divide both sides until you isolate k by itself. Thanks!

Answer 3

You are welcome.