Does the Spring Continue to Stretch Indefinitely Beyond the Elastic Limit?

[rollcast]

Homework Statement

The Attempt at a Solution

Its question 1 A (III) I don't understand.

I have included a copy of the question paper and the mark scheme.

I understand the continuation of the straight line up to 800N however after does the line curve like the blue / red one on my diagram?

I would have thought it should have leveled off at a constant length as after the spring is past the elastic limit it will only stretch so far before it turns into a straight bit of wire?

The mark scheme would suggest that the spring should continue to stretch to infinity as more weights are added?

Thanks
Al

 

[Doc Al]

Once past the elastic limit the spring may stretch way more than per Hooke's law. And it won't return to it's unstretched length once the weight is removed. You are correct, of course, that at some point the spring may unravel and be nothing but a straight wire. I don't think they intend for the graph to go that far.

 

[rollcast]

Once past the elastic limit the spring may stretch way more than per Hooke's law. And it won't return to it's unstretched length once the weight is removed. You are correct, of course, that at some point the spring may unravel and be nothing but a straight wire. I don't think they intend for the graph to go that far.

So its the Red curve then?

 

[Doc Al]

So its the Red curve then?

Yes, that's what I would say.