Re: E=F/q=vB Magnetic Force does not work on the charge

In sci.physics.relativity, guskz@xxxxxxxxxxx
<guskz@xxxxxxxxxxx>
wrote
on Mon, 16 Jul 2007 14:22:44 -0700
<1184620964.145801.131020@xxxxxxxxxxxxxxxxxxxxxxxxxxx>:
On Jul 15, 9:45 pm, "T.M. Sommers" <t...@xxxxxx> wrote:
gu...@xxxxxxxxxxx wrote:
On Jul 15, 1:11 pm, The Ghost In The Machine
<ew...@xxxxxxxxxxxxxxxxxxxxxxx> wrote:
In sci.physics.relativity, T.M. Sommers
<t...@xxxxxx>
wrote
on Sun, 15 Jul 2007 11:20:51 -0400
<469a3b52$0$25595$470ef...@xxxxxxxxxxx>:
gu...@xxxxxxxxxxx wrote:

Didn't know this was a course in Calculus or Algebra, how do you
calculate the work without multiplying.

You take the dot product. More specifically, you integrate the
dot product.

The dot product is a sum of scalar products, at least as
conventionally expressed. :-)

I simply 3x3=9 and nothing more. the others can dot as much as they
want.

Then you will get the wrong answer. The dot product depends on
the angle between the two vectors.

--
Thomas M. Sommers -- t...@xxxxxx -- AB2SB- Hide quoted text -

- Show quoted text -

If there be an angle I would at it to the formula, if there it be
perpendicular or parallel I doth not.


The dot product can also be expressed

a dot b = length(a) * length(b) * cos(angle(a,b))

In any event, absent considerations such as hitting dust,
a planet in a pure circular orbit does no work (at least
in Newtonian physics; GR predicts gravitational waves,
with the planet very slowly spiraling inward). The planet
is clearly moving but the force is always perpendicular
to its movement vector.

A planet in an elliptical orbit also does no work but the
considerations are more complicated.

cos(pi/2) = cos(90 degrees) = 0.

--
#191, ewill3@xxxxxxxxxxxxx
Useless C++ Programming Idea #889123:
std::vector<...> v; for(int i = 0; i < v.size(); i++) v.erase(v.begin() + i);

--
Posted via a free Usenet account from http://www.teranews.com

.