# Physics18.3.6 Coulomb's Law

#### karush

##### Well-known member
$\tiny{18.3.6 Coulomb's Law }$
$\text{A charge of$q_1=4.0 \mu \, C$is at origin, and charge}$
$\text{$q_2=6.0 \mu \, C$is on the x axis at$x=3.0 m$}$,
$\text{(a) find the force on the charge$q_2$}$
$\text{(b) find the force on$q_1$}$
$\text{(c) how would your answer for parts (a) and (b) dffer if$q_2=-6.0 \mu \, C $}$

ok I plan to take physics 151this fall
so trying to do some expected problems early

#### topsquark

##### Well-known member
MHB Math Helper
$\tiny{18.3.6 Coulomb's Law }$
$\text{A charge of$q_1=4.0 \mu \, C$is at origin, and charge}$
$\text{$q_2=6.0 \mu \, C$is on the x axis at$x=3.0 m$}$,
$\text{(a) find the force on the charge$q_2$}$
$\text{(b) find the force on$q_1$}$
$\text{(c) how would your answer for parts (a) and (b) dffer if$q_2=-6.0 \mu \, C $}$

ok I plan to take physics 151this fall
so trying to do some expected problems early
Start with Coulomb's law!

$$\displaystyle F = \dfrac{k q_1 q_2}{r^2}$$ or $$\displaystyle F = \dfrac{1}{4 \pi \epsilon _0} \dfrac{q_1 q_2}{r^2}$$

(Hint: The force on q1 is the same as the force on q2. Why?)

-Dan