Answer: 0.064 N
Explanation:
According to Coulomb's Law:
[tex]F_{E}= K\frac{q_{1}.q_{2}}{d^{2}}[/tex]
Where:
[tex]F_{E}[/tex] is the electrostatic force
[tex]K=8.99(10)^{9} Nm^{2}/C^{2}[/tex] is the Coulomb's constant
[tex]q_{1}[/tex] and [tex]q_{2}[/tex] are the electric charges
[tex]d[/tex] is the separation distance between the charges
For the first case we have [tex]F_{E}=0.57 N[/tex] and [tex]d=1.37 m[/tex]. So, we will isolate [tex]q_{1}[/tex] [tex]q_{2}[/tex] first:
[tex]q_{1}.q_{2}=\frac{F_{E}d^{2}}{K}[/tex]
[tex]q_{1}.q_{2}=\frac{(0/57 N)(1.37 m)^{2}}{8.99(10)^{9} Nm^{2}/C^{2}}[/tex]
[tex]q_{1}.q_{2}=1.19(10)^{-10}C^{2}[/tex]
Now, for the second case, we will have the same value for [tex]q_{1}[/tex] [tex]q_{2}[/tex], but [tex]d=4.08 m[/tex] this time and we have to find [tex]F_{E}[/tex]:
[tex]F_{E}=8.99(10)^{9} Nm^{2}/C^{2}\frac{1.19(10)^{-10}C^{2}}{(4.08 m)^{2}}[/tex]
[tex]F_{E}=0.064 N[/tex] As we can see this value is less than [tex]0.57 N[/tex] because the distance between charges was increased.