Answer :
Answer:
[tex]{F_{tot} = -1.092*10^{-2}N[/tex]
Explanation:
The question: What is the net force exerted by these two charges on a third charge q_3 = 47.0 nC placed between q_1 and q_2 at x_3 = -1.240 mm ?
Your answer may be positive or negative, depending on the direction of the force.
Solution:
The coulomb force is given by the equation
[tex]F =k\dfrac{q_1 q_2}{d^2}.[/tex]
where [tex]d[/tex] is the separation between the charges [tex]q_1[/tex] and [tex]q_2[/tex].
Now, in our case
[tex]q_1=-13.5nC=-13.5*10^{-9}C[/tex]
[tex]q_2=-1.735nC=-1.735*10^{-9}C[/tex]
[tex]q_3= 47*10^{-9}C[/tex]
The separation between charges [tex]q_3[/tex] and [tex]q_1[/tex] is
[tex]d_{31}= (-1.240mm)-(-1.735mm)=0.495mm=4.95*10^{-4} m[/tex]
Therefore, the force between them is
[tex]F_{31} = (9*10^9NmC^{-2})\dfrac{47*10^{-9}*(-13.5*10^{-9})}{4.95*10^{-4}} =-0.01152N[/tex]
and it is directed in the negative x-direction.
The separation between charges [tex]q_2[/tex] and [tex]q_3[/tex] is
[tex]d_{23} =-1.240mm-0=-1.240*10^{-3}m[/tex]
therefore, the force between them is
[tex]F_{23} =(9*10^9Nm^2C^{-2})\dfrac{47*10^{-9}C*(-1.735*10^{-9}C)}{-1.240*10^{-3}m}=5.94*10^{-4}N[/tex]
Therefore the total force on charge [tex]q_3[/tex] is
[tex]F_{tot} =5.94*10^{-4}-0.01152N = -0.010926N\\\\\boxed{F_{tot} = -1.092*10^{-2}N}[/tex]