- #1
con31773
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Homework Statement
I'm having a little trouble with an electric force question I have been working on. It seems simple, but my answer keeps coming out incorrect. Using the graph, deduce the electric force vector on charge q3 by q1/2. In case it is not clear, q3 lies on point (2,2)
Homework Equations
F=(kq1q2)/r^2*[itex]\hat{r}[/itex]
The Attempt at a Solution
Okay, well since electric force vectors simply add to give resultant force I can deduced the individual vectors and sum, as such.
F(1/3)=(kq1q3)/r^2*[itex]\hat{r}[/itex](1/3)
and the same applies to the second charge
F(2/3)=(kq3q2)/r^2*[itex]\hat{r}[/itex](2/3)
then I deduced r for both. Simply being 2 for q(2/3), and 5 for q(1/3) (from pythagoras)
Then, the unit vectors, as (2[itex]\hat{i}[/itex]+[itex]\hat{j}[/itex])/5 for q(1/3)
and [itex]\hat{j}[/itex] for q(2/3)
Put it together I got
F(1/3)=((kq1q3)/25)(2[itex]\hat{i}[/itex]+[itex]\hat{j}[/itex])
F(2/3)=((kq2q3)/4)[itex]\hat{j}[/itex]
Evaluate and sum, I got, 0.367[itex]\hat{i}[/itex]-0.412[itex]\hat{j}[/itex]
which of course is not correct. I'm sure there is a mistake in there but can not find it. Would be greatful for some fresh eyes to tell me where.
Thank you in advance. :)