Re: Electrostatics problem

[Bob Sciamanda <trebor@VELOCITY.NET>]

Michael's CM argument is elegant, conclusive and the way to go.
However, in attempting to cleanup my algebraic approach, a lesson is
learned:

Define:
A = angle of elevation of the line joining the equal masses
T1,T2 = angles of the strings from the vertical
F = the coulomb force magnitude.

Then:

T1*cosT1 = mg + F*sinA
T2*cosT2 = mg - F*sinA
T1*sinT1 = T2*sinT2  (cuz each  = F*cosA)

Manipulating these gives:

tanT1 = tanT2 / ( [2mg/T2*cosT2] - 1)

This sez T1=T2 only if mg = T2*cosT2

One has to notice that this then forces A=0. !!!

A good lesson in the intricacies of crank turning.

But is this solution forced by the above equations alone? What must be
added?

Bob

Bob Sciamanda (W3NLV)
Physics, Edinboro Univ of PA (em)
trebor@velocity.net
http://www.velocity.net/~trebor