In Fig. 21-24, the particles have charges q1 = -q2 = 400 nC and q3 = -q4 = 92 nC, and distance a = 5.0 cm. What are the (a) x and (b) y components of the net electrostatic force on particle 3?

The figure cannot be uploaded, but the particles are located as a square, with q1 in the upper left, q2 in the upper right, q3 in the lower left, and q4 in the lower right.

2 answers

F13=k•q1•q3/a² =
=9•10^9•400•10^-9•92•10^-9/25•10^-4=
=0.132 N
F13(x) =0, F13(y) =0.132 N
F43= k•q4•q3/a² =
=9•10^9•92•10^-9•92•10^-9/25•10^-4=
=0.0305 N
F43(x)= - 0.0305 N. F43(y)= 0
F23= k•q2•q3/(a√2)²= 9•10^9•400•10^-9•92•10^-9/1.41•25•10^-4=0.0936 N
F23 directed along the diagonal of the square (towards q2)
F23(x) =F23(y)=
=0.0936•cos 45=0.0936•0.707=0.0662 N.

F(x) = F13(x) +F43(x) +F23(x) =
=0 - 0.0305+ 0.0662= 0.0357 N,
F(y) = F13(y) +F43(y) +F23(y)= 0.132+0+0.0662 =0.1982 N.
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