1. 7.2 x 10-7 N attraction 2.1 x 10-7 N repulsion A on B / B on A
qA = - 4 x 10-9 C
qB = 5 x 10-9 C
d = 0.5 m
k = 9 x 109
7.2 x 10-7 N attraction
F = ? N
B on C / C on B
qB = 5 x 10-9 C
qC = 3 x 10-9 C
d = 0.8 m
k = 9 x 109
F = ? N
2.1 x 10-7 N repulsion

2. 6.4 x 10-8 N attraction charge A . . . . ΣF = 7.84 x 10-7 N right
A on C / C on A
qA = -4 x 10-9 C
qC = 3 x 10-9 C
d = 1.3 m ( )
k = 9 x 109
F = ? N
6.4 x 10-8 N attraction 1)
charge A ΣF = 7.84 x 10-7 N right
charge B ΣF = 9.3 x 10-7 N left
charge C ΣF = 1.46 x 10-7 N right 2)
charge B . . ΣF = 1.66 x 10-4 N
@ 74.3° above the x-axis