(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

Point charge 3.5microC is located at x = 0m, y = 0.30m , point charge -3.5microC is located at x= 0m y= -0.30m . What are (a)the magnitude and (b)direction of the total electric force that these charges exert on a third point charge Q= 4.5microC at x= 0.40m , y= 0m?

2. Relevant equations

These are the equations I've been using:

Coulomb's Law

F = k*(absolute_value(q1*q2)/r^2)

Law of Cosines

c^2 = a^2+b^2-2abcos(∅)

Magnitude of a Force

F = sqrt(Fy^2+Fx^2)

3. The attempt at a solution

1) I drew out the situation on a standard xy-plot. I then made a force diagram with Q as the origin and q2 .5m (used the pythagorean theorem to calculate this) from Q on the x-axis and q1 ∅ degrees from the x-axis and .5m from Q. I used the law of cosines to calculate ∅ (I got 73.7398 degrees)

2) set the sum of forces to:

= (1/4*pi*ε0)*(absolutevalue(q2*Q)/r^2)*cos∅ + (1/4*pi*ε0)*(absolutevalue(q2*Q)/r^2)*sin∅ + (1/4*pi*ε0)*(absolutevalue(q1*Q)/r^2)

3)I then plugged in the values to the equations (I converted microC to C and had ∅)

and got Fx = .724792N and Fy = .543594N

4) I used the magnitude of a force equation and received the value .90599N

Any help would be appreciated!

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# Homework Help: Coulombic Force on Q from two particles

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