[Arm-netbook] 15in EOMA-68 laptop

[luke.leighton]

ok.  centre of gravity stuff.  we're looking at the *furthest* back
edge to ensure the laptop doesn't tip up.

* http://encyclopedia2.thefreedictionary.com/Magnesium+Alloys
* density of magnesium alloys: 1700kg/m.m.m.
* http://www.robotroom.com/Elemental-Cylinders-1.html
* aluminium: 2700kg/m.m.m

metal weight calculator:
* http://www.micas.co.uk/calculator.htm

trig calculator:
* http://easycalculation.com/trigonometry/trigonometry.php

* weight of LCD: 440g
* weight of back metal part:
  - assume 0.5mm thickness of metal
  - sheet 360x260x0.5mm minus 340x220
  - 0.0776 kg - 0.0672 kg = 0.010 kg
* total weight: 450g call it 0.5kg just because.

* moment of inertia about hinge = weight times 1/2 length
* assume an angle of 30 degrees on the lid
  - 260mm / 2 * sin(30) = 260 * 0.5 * 0.5 = 65mm
* assume benson's design where lid is offset back by say 65mm (to
allow CPU Card)
  - subtract an additional 65mm because it's offset

...... perfect!!!  awesome!  no need to do any further calculations,
because the centre of gravity of a 0.5kg lid happens by a complete
coincidence to be directly above the back line @ 65mm.

any weight that _is_ in the front part will therefore keep it leaning
forward, no matter how little weight that is.

how about that? :)

l.