.9=kq1(6-q1)e-6/.4^2
solve for q1. notice it is a quadratic, use the quadratic equation.
The sum of two point charges is 6µC. They attract each other with a force of 0.9N, when kept 40cm apart. Calculate the charges.
2 answers
Q2 = [6*10^-6 Coulombs + Q1] because attracting one must be + and the other -
.9 = k Q1Q2/0.40^2
.9*.16 = 9*10^9 (Q1)(-6*10^-6+Q1)
16*10^-12 = -6*10^-6 Q1 +Q1^2
Q1 ^2 - 6*10^-6 Q1 - 16 *10^-12 = 0
pretend it is Q1^2 - 6 Q1 - 16 =0
(Q1 - 8)(Q1+2) = 0
so one is 8 * 10^-6 then the other is -2 * 10^-6
.9 = k Q1Q2/0.40^2
.9*.16 = 9*10^9 (Q1)(-6*10^-6+Q1)
16*10^-12 = -6*10^-6 Q1 +Q1^2
Q1 ^2 - 6*10^-6 Q1 - 16 *10^-12 = 0
pretend it is Q1^2 - 6 Q1 - 16 =0
(Q1 - 8)(Q1+2) = 0
so one is 8 * 10^-6 then the other is -2 * 10^-6
1 answer