Electrostatics - Question about the direction of the force.

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SUMMARY

The discussion centers on calculating the electrostatic forces between two point charges, q1 = -2nC and q2 = +5nC, separated by 4 cm. The calculated forces are -45 kN on q1 and 112.5 kN on q2, derived using the formula F = k*q1*q2/r^2, where k = 9x10^9 N m²/C². The direction of the forces is clarified: the force on q1 is directed towards q2 due to the attraction between opposite charges, while the force on q2 is directed away from q1. Newton's Third Law confirms that these forces are equal in magnitude and opposite in direction.

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stobbz
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Homework Statement



Two point charges, q1 = -2nC & q2 = +5nC are 4 cm apart. What is the force on q1? What is the force on q2? (Magnitude and Direction)

Homework Equations



F = kq/r^2
k = 9x10^9

The Attempt at a Solution



Using that formula, I calculated q1 to equal -45kN and q2 to equal 112.5 kN (Which seems awfully large to me). I don't understand what the question needs in terms of a direction. It would make more sense to me if there were a set of coordinate related to the question.

Any help appreciated,
Cheers!
 
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stobbz said:
Using that formula, I calculated q1 to equal -45kN and q2 to equal 112.5 kN (Which seems awfully large to me). I don't understand what the question needs in terms of a direction. It would make more sense to me if there were a set of coordinate related to the question.

Any help appreciated,
Cheers!

If you show exactly what numbers you put where, we might be able to find out where you went wrong.

As far as the direction is concerned, does the force on q1 point towards q2 or away from q2? What the force on q2?

As far as the magnitudes of the forces are concerned, you need to brush up on Newton's Third Law.
 
the formula for electrostatic force is k*q1*q2/r^2 be careful about the units
 

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