On Sun, 19 Oct 2003 21:55:45 +0100, "Andrew Coppin"
<orp### [at] btinternetcom> wrote:

>Any hints on how the real physics works would be appreciated.

Others already mentioned Hooke's Law, I will just add minor but
important details.

Hooke's Law relates stress, strain and Young's modulus of elasticity. 

Stress is absolute (not mathematically speaking, but physically
speaking). It is measured in N/m^2 can be basically considered to be
equivalent to pressure. Note that the denominator represents area,
i.e. a cross-section, so for uniform cross-sections (like a bar) it
can directly represent force. Stress is a tensor but for simple 1-D
problems can be treated as a numeric value.

Strain is a relative quantity (this is important) and shows how much
the object has "stretched". Technically, it is a tensor, like stress,
but the case of long, thin objects can be treated as one-dimensional
and thus purely algebraic. Strain is defined as (L - L_0)/L_0 or in
words, the change in length (positive if stretching, negative if
compressing) divided by the original length.


Peter Popov ICQ : 15002700
Personal e-mail : pet### [at] vipbg
TAG      e-mail : pet### [at] tagpovrayorg

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