Question 1178647
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The formula F=Kq1q2/r^2 gives the force between two point charges of q1 and q2 coulombs that are r metres apart. 
If two equally charged balls are placed 0.1m apart and the force between the balls is 9.8*10^-4 Newtons, 
calculate the charge on each ball to 2 significant figures, given K=9.0*10^9.
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        Calculations in the post by @mananth are incorrect.

        I came to bring a correct solution.



<pre>
F = {{{K*((q1*q2)/r^2)}}}

r = 0.1

F = 9.8*10^-4 Newtons,

K = 9.0*10^9.

q=?


    Substitute the values into the basic formula


{{{9.8*10^(-4)}}} = {{{(9.0*10^9) *(q^2/ 0.1^2)}}}

{{{q^2}}} = {{{((9.8*10^(-4))*(0.1^2))/ (9.0*10^9)}}}

{{{q^2}}} = {{{(9.8/9.0)*10^(-15)}}}

{{{q^2}}} = {{{1.0888 * 10^(-15)}}} = {{{10.888 * 10^(-16)}}}

q = {{{3.23*10^(-8)}}}     <<<---===  <U>ANSWER</U>
</pre>

Solved.