Physics
posted by Rachel .
If a 40 kg brick and a 400 kg brick each dropped from 1 m above a trampoline, find the lowest position of each brick. Assume the trampoline is a simple spring obeying Hooke's law with a k value of 12 000 N/m.
I know i must use Fs= kx,
but where do I start?
Do i find Fg at 1 m?

I would do it with energy.
mg(h+x)=1/2 k x^2
then solve for x in each case. 
okay, but what is the start of that eq'n?
It looks similar to Eg=Ek ? 
PEintrampoline=PE gravity lost

pe= potential energy?

and how do i solve for x when it is on oth sides of the eq'n?

multiply it all out, you will get a quadratic equation. Use the quadratic formula.