Calculating electrostatic force on particles

[Jrlinton]

Homework Statement

Homework Equations

F=(kq1q2)/d^2

The Attempt at a Solution

So it should be fairly easy to use "parts" to come up with each answer
Part a
Because particle 1 has no pull in the x direction I should be able to ignore it when finding the x component of the force
Fx=k*q3*q4/a^2+k*q3*q2/(a*sqrt2)^2*cos45
=7.46E-4 N
This was incorrect and I did not attempt part 2 as I figured my mistake would carry over to that similar calculation

 

[BvU]

Check your calculation. I get something else. Spell it out if you want it checked.

 

[Jrlinton]

8.99E9*(9.5E-8)*(-9.5E-8)/(2.03E-3)+8.99E9*(9.5E-8)(-5E.7)/(4.05E-3)cos45deg
=-0.114623N
it seems that I made a mistake on my cm to m conversion and if I remember correctly this should be absolute value of the charges so
=0.114623N

 

[BvU]

Numerical value same as what I found.

if I remember correctly this should be absolute value of the charges

No. You are asked for an x-component, which can be negative or positive. Make a sketch to find the right sign. What does the F in your relevant equation represent ?

 

[Jrlinton]

I realized this after I sent it. Both q2 and q4 are opposite charges of q3 so they are both attractive forces. In regards to the y component q1 will repel q3 while q2 will again be attractive and by glance you can tell the effect of q1 will be greater than q2 you can assume that the answer will be negative in the y direction

 

[BvU]

Assuming is one thing, calculating is better .