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## Homework Statement

Suppose that two balls of mass 1.5x10

^{-4}kg each carry equal charges and are suspended by identical threads of length 11cm anchored 28cm apart. If each thread makes an angle of 20 degrees with the vertical, what is the charge on each ball?

## Homework Equations

F=kq

^{2}/r

^{2}

## The Attempt at a Solution

From a free body diagram of one of the masses:

mg=Tcos20

Fe=Tsin20

which can be combined to Fe = mgtan20

using the above equation:

q=(mgtan20/k)

^{1/2}(0.28m)

using this, I get 6.8x10

^{-8}C

can some one point out where I'm going wrong?