From: Bilge on
Ka-In Yen:
>
>Bill Hobba wrote:
>> "Ka-In Yen" <yenkain(a)yahoo.com.tw> wrote in message
>> news:1144112932.833871.196670(a)i39g2000cwa.googlegroups.com...
>> > Bill Hobba wrote:
>> >> "Ka-In Yen" <yenkain(a)yahoo.com.tw> wrote in message
>> >> news:1144028073.121452.279020(a)j33g2000cwa.googlegroups.com...
>> >> > Is it useful?
>> >> > 2. Linear mass density is a vector.
>> >> >
>> >> > M/(l<i:3>)=(M/l) (kg/m)<i:3>
>> >> You can not divide by vectors.
>> > Why?
>>
>> http://www.mcasco.com/qa_vdq.html
>
>Dear Bill,
>
>Thank you for the information you provide. You were misled by
>mathematician. Mathematicians play vectors without unit(meter
>for example); that's not for physicists.

Well, I'm a physicist and as far as I can tell, you haven't yet
said anything that makes an physical sense, regardless of what you
want to claim about mathematics.

> Area = Length * Height
> Height = Area / Length
>
>I learned the above equations when I was a pupil in elementary
>school. Dividing an area by a length, we always get the height
>of a rectangle(although infinite number of parallelograms have
>the same area and length).

What does that have to do with dividing by vectors? All you wrote
were magnitudes.

>Physicists have been doing vector-by-vector-division for a
>hundred years. The equation of magnetic force is "vector division
>by vector".

No, it is not.

>F=iLXB (X is corss product).

Note that L is a vector and B is a pseudovector and those are
not dividing anything.


From: Ka-In Yen on
Dear Bilge,
Thank you for your comment.

Bilge wrote:
> Ka-In Yen:
> >
> >With Clifford's method, we can get the same result.
>
> No, you don't. Feel free to write down the expression in terms of
> the clifford algebra.
>

Clifford proves k / <a,b,c> = k<a,b,c> / <a,b,c>^2

[Proof]
k/<a,b,c>=[k<a,b,c>]/[<a,b,c>^2]
=(k/l) <i,j,k>
where l=sqrt(a^2+b^2+c^2) is the magnitude of <a,b,c>,
and <i,j,k>=<a,b,c>/l is the unit vector of <a,b,c>.
[End of proof]

> >Do you have any strong reason to reject Clifford's method?
>
> >In 3D VECTOR algebra, we have to divide a mass by a length
> >VECTOR, and linear mass density is a VECTOR.
>
> Wrong. Given a linear mass density lying along -a < x < a, what
> direction does it point?

We are talking about 3D vector algebra, your question is 1D.

two points : (-a, y, z) m and (a, y, z) m (m is meter).
length vector: (a,y,z)m - (-a,y,z)m = <2a,0,0>m
mass of a straight wire between the above two points is M kg.

linear mass density = M kg / <2a,0,0>m
= (M/2a) <1,0,0> kg/m

From: Bilge on
Ka-In Yen:
>Dear Bilge,
>Thank you for your comment.
>
>Bilge wrote:
>> Ka-In Yen:
>> >
>> >With Clifford's method, we can get the same result.
>>
>> No, you don't. Feel free to write down the expression in terms of
>> the clifford algebra.
>>
>
>Clifford proves k / <a,b,c> = k<a,b,c> / <a,b,c>^2

Define your notation.

>[Proof]
> k/<a,b,c>=[k<a,b,c>]/[<a,b,c>^2]
> =(k/l) <i,j,k>
> where l=sqrt(a^2+b^2+c^2) is the magnitude of <a,b,c>,
>and <i,j,k>=<a,b,c>/l is the unit vector of <a,b,c>.
>[End of proof]
>
>> >Do you have any strong reason to reject Clifford's method?
>>
>> >In 3D VECTOR algebra, we have to divide a mass by a length
>> >VECTOR, and linear mass density is a VECTOR.
>>
>> Wrong. Given a linear mass density lying along -a < x < a, what
>> direction does it point?
>
>We are talking about 3D vector algebra, your question is 1D.

Oh, in other words, wires don't exist in 3-d?

>
>two points : (-a, y, z) m and (a, y, z) m (m is meter).
>length vector: (a,y,z)m - (-a,y,z)m = <2a,0,0>m
>mass of a straight wire between the above two points is M kg.
>
>linear mass density = M kg / <2a,0,0>m
> = (M/2a) <1,0,0> kg/m
>
From: Ka-In Yen on
Dear Bilge,
Thank you for your comment.

Bilge wrote:
> Ka-In Yen:
> >Bill Hobba wrote:
> >> http://www.mcasco.com/qa_vdq.html
> >Thank you for the information you provide. You were misled by
> >mathematician. Mathematicians play vectors without unit(meter
> >for example); that's not for physicists.
> Well, I'm a physicist and as far as I can tell, you haven't yet
> said anything that makes an physical sense, regardless of what you
> want to claim about mathematics.
> > Area = Length * Height
> > Height = Area / Length
> >
> >I learned the above equations when I was a pupil in elementary
> >school. Dividing an area by a length, we always get the height
> >of a rectangle(although infinite number of parallelograms have
> >the same area and length).
>
> What does that have to do with dividing by vectors? All you wrote
> were magnitudes.

According to mathematician's opinion:
"Again there are two unknowns, |V| and u, in the equation so there are
infinitely many answers. Therefore cross division is also undefined."
---- http://www.mcasco.com/qa_vdq.html

That's not true. Stupid mathematicians hinder the development
of 3D vector algebra.

An area vector is A<i:3>m^2, and its length is l<j:3>m.
where <i:3> and <j:3> are unit vectors and m is meter.
We can divide the area vector by the length vector, and
we get the height(vector) of rectangle.

A<i:3>m^2 / l<j:3>m
=(A/l) <i:3>x<j:3> m (x is cross product)
=(A*sin(theta)/l) <k:3> m (<k:3>=(<i:3>x<j:3>)/sin(theta))
where theta is the angle between <i:3> and <j:3>.
<k:3> is a unit vector and perpendicular to <i:3> and <j:3>.

Or

A<i:3>m^2 / l<j:3>m
=A/(l <i:3>x<j:3>) m
=A/(l*sin(theta)) <k:3> m

>
> >Physicists have been doing vector-by-vector-division for a
> >hundred years. The equation of magnetic force is "vector division
> >by vector".
>
> No, it is not.
>
> >F=iLXB (X is corss product).
>
> Note that L is a vector and B is a pseudovector and those are
> not dividing anything.

As soon as you accept Clifford's method, you will realize that
LXB is vector by vector division.

From: Eric Gisse on

Ka-In Yen wrote:
> Dear Bilge,
> Thank you for your comment.
>
> Bilge wrote:
> > Ka-In Yen:
> > >Bill Hobba wrote:
> > >> http://www.mcasco.com/qa_vdq.html
> > >Thank you for the information you provide. You were misled by
> > >mathematician. Mathematicians play vectors without unit(meter
> > >for example); that's not for physicists.
> > Well, I'm a physicist and as far as I can tell, you haven't yet
> > said anything that makes an physical sense, regardless of what you
> > want to claim about mathematics.
> > > Area = Length * Height
> > > Height = Area / Length
> > >
> > >I learned the above equations when I was a pupil in elementary
> > >school. Dividing an area by a length, we always get the height
> > >of a rectangle(although infinite number of parallelograms have
> > >the same area and length).
> >
> > What does that have to do with dividing by vectors? All you wrote
> > were magnitudes.
>
> According to mathematician's opinion:
> "Again there are two unknowns, |V| and u, in the equation so there are
> infinitely many answers. Therefore cross division is also undefined."
> ---- http://www.mcasco.com/qa_vdq.html
>
> That's not true. Stupid mathematicians hinder the development
> of 3D vector algebra.

Only a crank complains about "stupid mathematicians".

[snip]

Yet for all your idiotic notation, you are unable to demonstrate that
your vector "division" has an inverse.

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