Quote:
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Originally Posted by DavidNJ
I used MathCad, which defaults to Joules. I change the units to lbf-ft, and it does the coversion. The quick part was assuming the flywheel clutch is a unitform disc, etc. I may have overcalculated the energy in the flywheel/clutch at idle...but not by an order of magnitude.
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Go on then, put me out of my misery! What have I done wrong:
We have a 40 lb flywheel 11" in diameter at 800 rpm,
Rotational mass (I)= 0.5 * m * r^2
so
I = 2420 = 0.5 * 40 * 11^2
Energy = 0.5 * I * w^2
so
774400000 = 0.5 * 5280 * 800^2
We also have a 2800 lb car travelling at 5 mph,
to make a comparison we need to convert mph to inches per minute
v = 5 / 60 * 63359 = 5280
Energy = 0.5 * m * v^2
39028528010 = 0.5 * 2800 * 5280^2
My energies are a factor of 50 apart!