Question

In the figure above, knowing that K = 9 x109 Nm2 /C2, Find? a) F13 (force of Q1 on Q3) b) F23 c) The net force (Fnet) on Q3

Answer 1

`"Please,have a look the fallowing details."`

Explanation:

• The Q3 charge is affected by both Q1 and Q2 charges. We must draw the force vectors by calculating these forces separately.

• The Q3 charge is attracted by the Q1 charge. The Force vector has shown as red colored.

`color(red)(F_("13")=k*(Q_1*Q_3)/r^2)=9.10^9*(8*10^(-6)*(-5*10^(-6)))/(5*10^(-2))^2`

`color(red)(F_("13")=k*(Q_1*Q_3)/r^2)=(-72*cancel(5)*10^(-3))/(cancel(25)*10^(-4))=-(720)/5=-144N`
`"A negative sign indicates that two charges pull each other."`

• The Q3 charge is pushed by the Q2 charge. The Force vector has shown as green colored.

`color(green)(F_("23")=k*(Q_2*Q_3)/r^2)=9.10^9*((-9*10^(-6))*(-5*10^(-6)))/(5*10^(-2))^2`

`color(green)(F_("23")=k*(Q_2*Q_3)/r^2)=(81*cancel(5)*10^(-3))/(cancel(25)*10^(-4))=(810)/5=+162N`

`"A positive sign indicates that two charges push each other."`

• The charge Q3 is affected by two forces .These are the same direction.

`F_("net")=color(red)(F_("13"))+color(green)(F_("23"))`

`F_("net")=144+162=306N`