Q1: Is that a real gold star, or just an imaginary one? If it's a
real gold star then I'll derive it and I promise not to peek.
Otherwise I'll just look it up. Basically, the 33000 comes from
the fact that power is work / time, work is force * distance, 1
horsepower = 746 watts, 1 foot is 0.305 meter, 1 lb. is 4.45
newtons, then you plug it all into the basic physics equations
and you get 2*pi / 33000.
Q2: YES. If you get the same torque at higher RPM, then you can
use shorter gears at the same vehicle speed ('cuz the engine revs
higher) and that means you get a bigger gear ratio multiplier and
more torque at the wheel. Basically, when you can rev higher you
can use shorter gears without sacrificing vehicle speed. The
overall push of the car is the product of the gear ratio with the
crankshaft torque, so both are equally important for
acceleration.
P.S.
Alternately, you could say that power is torque times RPM, the
same torque at higher RPM is more power, and more power means you
can increase the kinetic energy of the car faster. Since mass is
constant (if you ignore decreasing mass due to fuel consumption),
increasing the kinetic energy of a car means making it go faster.
Andy McKee wrote:
>
> > P = 2 * pi * n * T / 33000
> > Where n is RPM and T is torque. Since 33000 / (2 * pi) is 5,252,
> > they are equal at 5,252 RPM.
> >
>
> I'll give you a gold star if you can say where the 33000 comes from without
> looking it up.
>
> > In short, the higher RPM at which you get your torque, the more
> > acceleration you get. Power is torque multiplied by RPM.
> >
>
> So, by your logic I will accelerate faster with 500ft-lbs at 5000rpm than
> 500ft-lbs at 1500rpm?
>
>
> -Andy
> Do You Yahoo!?
--
Michael R. Clements
mrc01@flash.net
A government big enough to give you everything you want
is also big enough to take away everything you have.
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