How do you measure how hard a surface is?
- Saturday Dec 5,2009 02:09 PM
- By diddy
- In Others
I need to know for a science experiment at school (using tennis balls). How do you measure hardness?
Just to avoid any confusion, i’m not measuring the hardness of the tennis balls, but of surfaces that tennis balls can be bounced on.
Confusion, Science Experiment, Surfaces, Tennis Balls
One Comment
hardness is difficult. Some info below.
What are you measuring the hardness of? tennis balls don’t seem appropriate.
there are three principal operational definitions of hardness:
Scratch hardness: Resistance to fracture or plastic (permanent) deformation due to friction from a sharp object
Indentation hardness: Resistance to plastic (permanent) deformation due to a constant load from a sharp object
Rebound hardness: Height of the bounce of an object dropped on the material, related to elasticity.
The Brinell scale characterizes the indentation hardness of materials through the scale of penetration of an indenter, loaded on a material test-piece. It is one of several definitions of hardness in materials science.
Proposed by Swedish engineer Johan August Brinell in 1900, it was the first widely used and standardised hardness test in engineering and metallurgy. The large size of indentation and possible damage to test-piece limits its usefulness.
see the references for more info.
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