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

How much work is required in moving Q3 to infinity while Q1 and Q2 remain in their positions?

Q3-------a-------|

|-----------------| b

Q1-------------Q2

a = 16.0 cm

b = 6.0 cm

Q1 = 5.70 μC

Q2 = -5.70 μC

Q3 = 1.8 μC

2. Relevant equations

W=ΔPE

PE=kQ1Q2/r

3. The attempt at a solution

Just added the potential energies associated with Q3 which is the work needed to move Q3 to infinity (i.e. bring said potential energies to 0).

kQ1Q3/r_{13}+ kQ2Q3/r_{23}

=(8.9875e9)(5.7e(-6))(1.80e(-6))/0.06 + (8.9875e9)(-5.7e(-6))(1.8e(-6))/sqrt(0.06^2 + 0.16^2)

=0.997 J

Also tried calculating ΔPE = final - initial (I think I messed up the formula, but somehow I got the negative of the first one)

(8.9875e9)(5.7e(-6))(-5.7e(-6))/.16 + 0.827790168702400828475759973771078927721678492943077184393)

= -0.997 J

Trying ΔPE again:

kQ1Q2/r_{12}- (kQ1Q3/r_{13}+ kQ2Q3/r_{23}+ kQ1Q2/r_{12})

=-kQ1Q3/r_{13}- kQ2Q3/r_{23}

=-(8.9875e9)(5.7e(-6))(1.8e(-6))/0.06 - (8.9875e9)(-5.7e(-6))(1.8e(-6))/sqrt(0.06^2 + 0.16^2)

= -0.997 J

What am I supposed to do? Neither of these work.

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# Homework Help: [Electromagnetism] How much work is required in moving Q3 to infinity?

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