hat is the point P shown in the stress-strain curve?*1 pointd) Breaking pointb) Elastic limita) Lower yield pointc) Proportionality limit

To identify the point P on the stress-strain curve, we need to understand what each of the mentioned points represents:

1. Breaking Point: This is the point on the stress-strain curve where the material ultimately fails and can no longer sustain any stress.

2. Elastic Limit: This is the maximum stress that a material can withstand without permanent deformation. Beyond this point, the material will not return to its original shape when the load is removed.

3. Lower Yield Point: This is a specific point in the yielding zone, where the material begins to deform plastically. It indicates the transition from elastic to plastic deformation.

4. Proportionality Limit: This is the point on the curve up to which the ratio of stress to strain remains linear (Hooke's Law applies). After this point, the material will still behave elastically but may not follow Hooke’s Law.

Based on these definitions, if we are looking for the point of first significant deformation, it would typically align with the Lower Yield Point (a).

In most stress-strain curves, Point P is often associated with either the Proportionality Limit or the Lower Yield Point, depending on context. Without the specific context of the curve referred to in the question, it's advisable to select:

Final Answer

a) Lower yield point as the most suitable answer, unless specifics indicate otherwise.