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Superposition of Forces: Finding Magnitude and Direction

  • Thread starter ecsx00
  • Start date
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Homework Statement


http://imgur.com/fvNbE
Part a needs to have up to 2 significant figures.
For part b. you need to find theta or the degrees counter clockwise from +x direction.


Homework Equations


Coulombs Law:
F = 9(10^9) |q1q2|/r^2
r = distance in meters of two charges


The Attempt at a Solution


Part A.
F(Q on q1) = 9(10^9) N*m^2/C^2 * (2*10^-6 C)(4*10^-6 C) / (0.5m)^2
= 0.288 N

F(q2 on q1) = 9(10^9) N*m^2/C^2 * (2*10^-6)^2 / (0.60m)^2
= 0.1 N

|F| = sqroot( (0.288 N)^2 + (0.1 N)^2 ) = 0.304867 N *I know this is wrong because I tried to submit this answer and it was no go.*


Part B.
atan(0.1 N/0.288 N) = 19.148 degress
180 - 19.148 = 160.852 degress
*For this part I figured I take 180 and subtract the degrees obtained to get the degrees counter clockwise of the +x direction.
 

Answers and Replies

  • #2
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Homework Statement


[PLAIN]http://imgur.com/fvNbE[/QUOTE] [Broken]

The image is not embedded properly. Please correct that.

|F| = sqroot( (0.288 N)^2 + (0.1 N)^2 ) = 0.304867 N *I know this is wrong because I tried to submit this answer and it was no go.*
This is wrong, because the forces from two charges are not perpendicular to each other. You need to find x and y components of each force, from those, get the x and y components of the resultant force, and then compute its magnitude and direction.
 
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