Posted by **Rachel** on Friday, November 6, 2009 at 10:19am.

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?

- Physics -
**bobpursley**, Friday, November 6, 2009 at 10:26am
I would do it with energy.

mg(h+x)=1/2 k x^2

then solve for x in each case.

- Physics -
**Rachel**, Friday, November 6, 2009 at 10:29am
okay, but what is the start of that eq'n?

It looks similar to Eg=Ek ?

- Physics -
**bobpursley**, Friday, November 6, 2009 at 10:31am
PEintrampoline=PE gravity lost

- Physics -
**Rachel**, Friday, November 6, 2009 at 10:37am
pe= potential energy?

- Physics -
**Rachel**, Friday, November 6, 2009 at 10:38am
and how do i solve for x when it is on oth sides of the eq'n?

- Physics -
**bobpursley**, Friday, November 6, 2009 at 10:39am
multiply it all out, you will get a quadratic equation. Use the quadratic formula.

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