An elevator cable breaks when a 920kg elevator is 28 m above a huge spring(adsbygoogle = window.adsbygoogle || []).push({});

(k=2.2 x10^5 N/m) at the bottom of the shaft.

Calculate a) the work done by gravity on the elevator before it hits

the spring b) the speed of the elevator just before striking the spring

and c) the amount of spring compresses

( note that work is done by both the spring and the gravity in this part )

I've calculated part a) and b)

answer for a) is 2.5x10^5 J b) 23m/s

For part C) what i think is

Einitial = Efinal

E(ball touches spring) = E(spring compresses)

1/2mv^2 +mgy + 1/2ky^2 = 1/2mv2^2 + mgy2 + 1/2ky2^2

Apparantly that's the equation in the book, but i have no idea how to do the question

Thanks!!

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# Homework Help: Elevator and Spring question

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