Solution :
Length of the plastic rod , L = 1.6 m
Total charge on the plastic rod , Q =
C
The rod is divided into 8 pieces.
a). The length of the 8 pieces is , 

= 0.2 m
b). Location of the center of the piece number 5 is given as : 0 m, -0.09375 m, 0 m.
c). The charge q on the piece number 5 is given as


=
C
d). WE approximate that piece 5 as a point charge and we need to find out the field at point A(0.7 m, 0, 0) only due to the charge.
We know, the Coulombs force constant, k =
So the X component of the electric field at the point A is given as

= -126.15 N/C
The Y component of the electric field at the point A is

= -16.93 N/C
Now since the rod and the point A is in the x - y plane, the z component of the field at point A due to the piece 5 will be zero.
∴ 
Thus, 