# Book contridictions

#1
Hi.
I am looking at a page on two Science books regarding Hooke's Law in AS Physics...
Oxford:
https://s7.postimg.cc/94t4xq2wb/20180425_092219.jpg

Cgp:
https://image.ibb.co/b1uFH7/20180328_122936.jpg

The Oxford book and CGP have a point placed in the same position on the graph, (A in the Oxford book and P in the CGP book). According to the Oxford book the point A/P represents the elastic limit of the string, beyond that point the spring will not return to its original shape. However according the CGP book, the point A/P represents the limit of proportionality, beyond that point the spring will not be supported by the Hooke's linear relationship law. Although the so is still ELASTIC and WILL RETURN TO ITS ORIGINAL SHAPE when the forces are removed (up until point B/E).

The other point (B/E) also haves different meanings in the two books. Point B/E in the Oxford appears as a example point beyond the Elastic Limit of A where the spring will now undergo plastic deformation. However according to the CGP book, point B/E IS the elastic limit and only after that point will the spring undergo plastic deformation.

I have tried to summarize the differences between the two books here in an image:
https://serving.photos.photobox.com/...06bf8c23c6.jpg

Does anyone know a reason for these contridictions?

Thanks.
0
4 years ago
#2
(Original post by Al4stair)
Hi.
I am looking at a page on two Science books regarding Hooke's Law in
https://s7.postimg.cc/94t4xq2wb/20180425_092219.jpg

Cgp:
https://image.ibb.co/b1uFH7/20180328_122936.jpg

The Oxford book and CGP have a point placed in the same position on the graph, (A in the Oxford book and P in the CGP book). According tAS Physics...
Oxford the Oxford book the point A/P represents the elastic limit of the string, beyond that point the spring will not return to its original shape. However according the CGP book, the point A/P represents the limit of proportionality, beyond that point the spring will not be supported by the Hooke's linear relationship law. Although the so is still ELASTIC and WILL RETURN TO ITS ORIGINAL SHAPE when the forces are removed (up until point B/E).

The other point (B/E) also haves different meanings in the two books. Point B/E in the Oxford appears as a example point beyond the Elastic Limit of A where the spring will now undergo plastic deformation. However according to the CGP book, point B/E IS the elastic limit and only after that point will the spring undergo plastic deformation.

I have tried to summarize the differences between the two books here in an image:
https://serving.photos.photobox.com/...06bf8c23c6.jpg

Does anyone know a reason for these contridictions?

Thanks.
Looks like a typographic error in the Oxford book. Point A is the Limit of Proportionality and up to that point, extension obeys Hooke's Law: Extension is proportional to the applied force.

Point B is the Elastic Limit, beyond which extension is plastic and permanent deformation of the materiel results from the applied force exceeding this point.

Between points A and B, the extension is still elastic but does not obey Hooke's Law. The applied force no longer produces a proportional linear extension.

The CGP book is correct.
1
4 years ago
#3
(Original post by Al4stair)
Hi.
I am looking at a page on two Science books regarding Hooke's Law in AS Physics...
Oxford:
https://s7.postimg.cc/94t4xq2wb/20180425_092219.jpg

Cgp:
https://image.ibb.co/b1uFH7/20180328_122936.jpg

The Oxford book and CGP have a point placed in the same position on the graph, (A in the Oxford book and P in the CGP book). According to the Oxford book the point A/P represents the elastic limit of the string, beyond that point the spring will not return to its original shape. However according the CGP book, the point A/P represents the limit of proportionality, beyond that point the spring will not be supported by the Hooke's linear relationship law. Although the so is still ELASTIC and WILL RETURN TO ITS ORIGINAL SHAPE when the forces are removed (up until point B/E).

The other point (B/E) also haves different meanings in the two books. Point B/E in the Oxford appears as a example point beyond the Elastic Limit of A where the spring will now undergo plastic deformation. However according to the CGP book, point B/E IS the elastic limit and only after that point will the spring undergo plastic deformation.

I have tried to summarize the differences between the two books here in an image:
https://serving.photos.photobox.com/...06bf8c23c6.jpg

Does anyone know a reason for these contridictions?

Thanks.

I have a different opinion as compared to uberteknik.

CGP seems to describe a more general case. In certain material, the point of elastic limit and limit of proportionality coincides or is the same. But there are some materials that divide the elastic limit into two parts which are described in CGP – proportion part and curve part.
1
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