Re: Re: relay help req. (horsepower definitions)

Doug H wrote:

>Power, as you correctly stated, is an expression of work done per
>unit time. However, twisting equations around (for marketing
>purposes) requires breaking the rules of mathematics that are not
>generally considered refutable.

Doug,

So you're saying that my 115V,8A, 1.5hp(claimed),25k rpm Black and
Decker model 3315 router does not compare to the motor at:

http://www.oneida-air.com/1_5hp.htm

Which shows: Motor Specs-Leeson Industrial 1.5 HP Motor 110v/220v
17.2/8.6 amps 1.15 service factor

Because Obviously 8A does not equal 17.2A! And Watts are obtained
from the 'PIE' equation: Power(Watts) = I(Amps) x(times) E(Volts, or
electromotive force)

Router: 115 x 8= 920 watts Leeson motor: 110 x 17.2= 1892 watts

Using 746 watts equal one horsepower:

Router: 920/746= 1.233HP Leeson motor: 1892/746= 2.536HP

Why is the leeson motor rated only 1.5 HP??? Because of the two
things I've left out so far: RPM! and torque!

Let's use the mechanically derived 'rotating' HP definition:
hp = torque X rpm X 1/5252

BTW (.0001904 is 'about' 1/5252) and T= torque

Router: 1.5hp= ???T x 25000rpm x .0001904 simplifies to:
1.5/4.76 = .315 torque

Leeson motor: 1.5hp= ???T x 1725rpm x .0001904 simplifies to:
1.5/.32844 = 4.567 torque or (2.283 torque using 3450 as the rpm.
we'll ignore the 3450 rpm model since it simplifies directly to the
1725 model)

Now let's see if these two motors HP agree:

Router: .315 torque at 25000 rpm is 7875
Leeson motor : 4.567 torque at 1725 rpm is 7878

This is MUCH closer than the 746 Watts based example!!! What 'rules
of math' did I break???

>Marketing types see us tech-heads as stubborn in our refusal to
>compromise on "simple" issues (like whether or not one HP equals
>746W), whereas we see them as dishonest in their willingness to
>redefine or blatantly ignore the laws of physics for purposes of
>gain.

What laws of physics were redefined or ignored above? It would appear
the mechanical equation is much closer to the truth than the
electrical HP derivation!

The 'marketing types' are simply saying "If I do a tiny bit of work
REPEATEDLY, EXTREMELY FAST; it is the same as doing a larger amount
of work more slowly!"

Math and physics BOTH back this up!

The tech-heads are stubborn only in their answer that "if the work
NEEDING DONE CANNOT be 'properly' done in a 'tiny bit' fashion, then
it doesn't matter that the math and physics are not violated!"

The equation twisting I originally referred to is simply reducing one
side and increasing the other to keep things proper. Mathematics
allows (even depends) on this ability. On the other hand, physics is
NOT so simple, since it must deal in 'real world' issues.

Mathematicians can ask the ant to move the boulder by breaking it(the
boulder) apart into 'ant size' pieces, and reassembling it in the new
position; The physicist says the ant can't move the 'boulder' at all.
He can change the form of the boulder, and move that... But that IS
NOT moving the boulder!

This is what I said originally. The math IS correct. The
lawnmower 'stopped' by an anthill'(in a previous post) IS capable of
doing 'Horsepower' work, BUT it needs the work to be done in very
small 'pieces'.

THIS is the reason there is such an outrage against "What is a
horsepower". We don't like that the math, although correct, is
cheating by trying to break the task into what for us, is TOO SMALL
pieces.

Going the other way: If the '2 Great Dane' power to drag a woman over
the countryside were applied to dragging a metal lathe, would they
now be less powerful? Since they can't drag the lathe as far or as
fast? Or at all?

It's a trick question, really. The potential ability of the '2 Dane'
team has not changed at all. But, POWER, by definition is the ABILITY
to DO work in a TIMEFRAME. So they ARE less POWERFUL dragging the
lathe than they were dragging the woman! (assuming the lathe is at,
or near their 'dragging' capability). We won't even add friction to
the equation!

Hope this helps.

Ballendo