# The diagram above represents the stress-strain for a typical metal rod…

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## The diagram above represents the stress-strain for a typical metal rod. What does X represent?

A. Yield point

B. Breaking point

C. Elastic limit

D. proportional limit

B

## DETAILS…

• The first point is the proportionality limit, a point at which hooks law begins to fail, the straight line which ends here shows that this is the point where the strain on the material stops being linearly proportional to the stress applied.
• The second point is called the yield point. It is a point in which the material lost all of its elasticity and start behaving like a pure plastic, this is the point of plastic deformation.
• Point X is called the breaking point or fracture point, this is because, at this point the material cuts off totally.

### Now for the right answer to the above question:

1. Option A is incorrect. the yield point is the second or middle point.
2. Option B is correct. point X is the breaking point.
3. C is incorrect. elastic limit is just before the second point.
4. D is not the correct answer. The proportionality point is the first point.

## KEY-POINTS…

• Both the yield point and the elastic limit mean almost the same thing.
• The stress-strain curve is similar to the load-extension curve.
• At point x, the material becomes totally deformed, this is why its called the fracture or breaking point.

Use the questions and answers session to raise further questions and deal more on this topic…