Consider:

Brittle materials are approximately considered to be those having a fracture strain of less than about 5%.
My answer:.
I am not sure what the author is saying here. Is it percent elongation that has to be more than 5% to be consider brittle.??

Based on the provided statement, it states that brittle materials are considered to have a fracture strain of less than about 5%. Fracture strain refers to the amount of deformation or elongation a material undergoes before it fractures or breaks.

To understand this concept better, let's break it down:

1. Fracture Strain: Fracture strain is a measure of the deformation or elongation a material can undergo before it breaks. It is usually expressed as a percentage of the original length of the material.

2. Brittle Materials: Brittle materials are characterized by their tendency to fracture without significant plastic deformation. Unlike ductile materials, which can undergo substantial elongation before breaking, brittle materials exhibit limited deformability.

3. Less than about 5%: The statement suggests that materials with a fracture strain of less than approximately 5% are considered brittle. In other words, if a material shows a strain of less than 5% before it fractures, it falls into the category of a brittle material.

To determine if a material is brittle or not, you would evaluate its fracture strain. This can be done through experimental testing such as tension tests, where the material is subjected to elongation until it breaks. By measuring the strain at the point of fracture, you can determine if the material falls into the category of brittle or ductile.