# Homework Help: Does plywood follow hooke's law

1. Jun 7, 2008

### Amy54

does plywood follow hooke's law? is the young's modulus for plywood constant across the beam? :) and if u have any other hints with deam deflection im willing to have them :P
thanks!!

2. Jun 7, 2008

### mgb_phys

Most things follow Hooke's law for small enough deflections - it depends how far you need to push it!
I would have thought that if there were enough layers of lamination then the longtitudanal/transverse ones would cancel out to give a uniform sort of behaviour.

3. Jun 8, 2008

### FredGarvin

As a caveat to what MGB wrote: Most materials will follow Hooke's Law. However, the form of the law that it follows may not be what you are thinking of. The most generally quoted form of Hooke's is for 1-D, linear, isotropic, homogeneous materials, i.e. $$\sigma =\epsilon E$$.

Hooke's law in its most general form contains 81 variables that can accommodate pretty much any material characteristic in all three dimensions. So to answer your question, does plywood follow Hooke's Law...yes it does. Does it follow the 1-D description that everyone knows? No. It does not.

4. Jun 8, 2008

### mgb_phys

But if you just want to know if an 8x4 sheet of ply will bend if you stand in the middle it should be enough.

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