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## Homework Statement

A force stretches a wire by 2mm. A second wire of the same material and with the same area of cross-section and twice the length is also stretched by the same force. What will its stretch be?

## Homework Equations

F= (YA/L)ΔL

## The Attempt at a Solution

F, Y, and A are all equal

First wire:

F =(YA/L

_{1})*2 mm

Second wire:

F =(YA/2L

_{1})ΔL

1. I set them equal to each other to solve for ΔL

(YA/2L

_{1})ΔL = (YA/L

_{1})*2

2. I canceled out YA

ΔL/2L

_{1}= 2/L

_{1}

3. I multiplied both sides by 2L

_{1}to isolate ΔL

ΔL = 4 mm

Did I do this correctly? I'm unsure because I've received notes from a friend and they got a different answer for the same problem. Thanks in advance.