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## Homework Statement

Elevator initially at rest.

Equilibrium length L

_{0}=40.0cm

60-kg person stands on spring

L

_{1}= 32.0cm

The elevator than speeds upwards at 2.50 m/s

^{2}

What is the new length (L

_{2})

## Homework Equations

F

_{net}=ma

F

_{sp}=-kdeltaX

F

_{G}=mg

## The Attempt at a Solution

Taking down as positive y hat direction

**Before:**

F

_{net}=F

_{sp}+F

_{G}

0=-k(0.32-0.40)+(60.0)(9.81)

__K=-7358__

**After:**

F

_{net}=F

_{sp}+F

_{G}

ma=-kdeltaX+mg

m(-2.5)=-(-7358)(L

_{2}-0.40)+60(9.81)

L

_{2}=[{60(-2.5)-60(9.81)}/-(-7358)]+0.40

**=0.30m from equilibrium**

**I am confused since i don't know how this makes sense according to the coordinate system. (I know the answer is right as my prof posted the answer, not the work, just answer)**

At rest change in x = -0.08

When accelerating change in x= -0.10

**But since my coordinate system is set up so Y-hat is positive is the downward direction doesn't this mean my spring is being displaces upward?**

This doesn't make sense to me , can someone please explain very clearly?

This doesn't make sense to me , can someone please explain very clearly?