# Two charges of  -4 C  and  -2 C are positioned on a line at points  -6  and  4 , respectively. What is the net force on a charge of  -4 C at  1 ?

Mar 23, 2016

${F}_{\text{net"=5,04*10^9" }} N$

#### Explanation:

${F}_{\text{AC"=k*(q_A*q_C)/d^2" "F_"AC}} = k \cdot \frac{\left(- 4\right) \cdot \left(- 4\right)}{7} ^ 2$
${F}_{\text{AC}} = \frac{16 k}{49}$

${F}_{\text{BC"=k*(q_B*q_C)/d^2" "F_"BC}} = k \cdot \frac{\left(- 2\right) \cdot \left(- 4\right)}{3} ^ 2$
${F}_{\text{BC}} = \frac{8 k}{9}$

${F}_{\text{net"=F_"BC"-F_"AB}}$

${F}_{\text{net}} = \frac{8 k}{9} - \frac{16 k}{49}$

${F}_{\text{net}} = k \left[\frac{392 k - 144 k}{441}\right]$

${F}_{\text{net}} = k \left[0 , 56\right]$
${F}_{\text{net}} = 9 \cdot {10}^{9} \cdot 0 , 56$
${F}_{\text{net"=5,04*10^9" }} N$