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# Physics AS Watch

1. A steel bar has a rectangle cross section of 50mm by 40mm and is 2.0m long. Calculate the work done in extending it by 6.0mm. someone please help explain how to do this question, even just the formula will be helpful
2. (Original post by amy_elizabeth64)
A steel bar has a rectangle cross section of 50mm by 40mm and is 2.0m long. Calculate the work done in extending it by 6.0mm. someone please help explain how to do this question, even just the formula will be helpful
When posting questions it'd be helpful if you gave full info, you missed that E is to be taken as 2.0 x 10^11 nm^-2 which makes the question pretty much impossible.

Now, I don't do physics a level, but after a few YouTube videos I get the following:

Strain = 6mm/2m = 0.003

Stress = 0.003 x (2.0x10^11)

Force = stress x cross sectional area

Work done = force x distance moved

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