Two Electric Charges- Electric Force-Ranking

AI Thread Summary
The discussion revolves around ranking the electric force on a +5 C charge placed at point P, given seven arrangements of two electric charges, each 20 C, either positive or negative. Participants clarify the distances involved, confirming that all distances between charges and point P are 5 cm. The electric force is calculated using the formula Fe = k(q1q2)/r^2, considering both the magnitude and direction of the forces exerted by the charges. One participant suggests drawing force vectors to visualize the resultant force at point P. The conversation emphasizes understanding the forces' interactions based on charge types and distances.
jeandempsey
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Homework Statement


Below are seven arrangements of two electric charges. All of the charges are the same size, 20 C, but they are either positive or negative. Each figure also has a point labeled P that lies on a straight line with the two charges. The distance between any two items is all 5 cm. There are no other charges in this region. A +5 C charge is placed at point P. Rank the strength (magnitude only) of the electric force on the +5 C charge when it is placed at point P from greatest to least.

Screenshot2011-12-03at23621AM.png


Homework Equations


Fe= k(q1q2)/r^2

The Attempt at a Solution


help get me started please? :) I don't know how to get started.
 
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jeandempsey said:
The distance between any two items is all 5 cm.

What do you mean by that? Is 5 cm the distance from P of both the + and - charges?

ehild
 
between any two items is 5 cm. For example, in C,
between - and P it is 5 cm and between P and + it is 5 cm.
 
And what is the distance between + and - in B?
Anyway, the + and - charges are of the same in magnitude, so what about the force they exert on the charge at P if the distances are equal? What about the direction the forces? Draw the forces with arrows in the pictures, and determine the resultant.

ehild
 
Oh! I think I understand it now. Thank you
 
jeandempsey said:
Oh! I think I understand it now. Thank you
Hi jeandempsey. Welcome to PF.

Would you like to give your answers & your reasoning so that ehild or one of our other homework helpers can check that you really do understand this.
 
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