Two small pith balls, each of mass m = 12 g, are suspended by 1.2 m fine strings and are not moving. If the angle that each string makes with the vertical is q = 42.6 , and the charges on the two balls are equal, what is that charge (in microC)?(adsbygoogle = window.adsbygoogle || []).push({});

http://img386.imageshack.us/img386/5977/picmd8.th.jpg [Broken]

I equated the forces in x and y to zero:

Tcos42.6-117.6=0

T=159.76

Tsin42.6+Fe=0

plugging in 159.76

Fe=108

then i used the equation Fe=kQ^2/r^2

i solved for r by doing this:

r=2(1.2sin42.6)

r=1.6 m

I'm not sure if my steps are right. Can someone help me? Thanks in advance!

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# Homework Help: Pith ball Charges

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