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MP 17.72 change in U?

  • Thread starter watdawaq
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  • #1
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Homework Statement


A 33uC point charge is placed 36cm from an identical 33uC charge. A -2.5uC charge is moved from point a to point b in the figure:
http://session.masteringphysics.com/problemAsset/1096949/4/GIANCOLI.ch17.p72.jpg


Homework Equations


U=kq1q2/r


The Attempt at a Solution



I found Ui by using above equation for each r from the -2.5uC charge and found the difference.

Repeated for Uf when charge is moved from a->b.

Uf-Ui = 1.74J, but MP says this is incorrect. What am I missing?
 

Answers and Replies

  • #2
Doc Al
Mentor
44,904
1,169
Please show the details of your calculation.
 

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