How to determine angle of net force-electric charges of right triangle

  • Thread starter Coco12
  • Start date
  • #1
272
0

Homework Statement



The .274 and .88 was found using the equation of electrostatic force .


Homework Equations




K=q1q2/d^2

The Attempt at a Solution


Would I just tan inverse of .274N and .88N which would be 17 degrees. However my question is: how to determine the reference pt: would it just be 17 degrees or 180-17 degrees?
 

Attachments

Answers and Replies

  • #2
198
18
Draw the force vectors tip-to-tail and it should be clearer.
 
  • #3
272
0
It would be in the first quadrant so would it be 90 minus 17 or??
 
  • #4
198
18
It doesn't really matter as long as you're clear. State "x degrees clockwise from BA axis" or "y degrees counter clockwise from BC"
 
  • #5
272
0
Is this a foolproof way? Look at the signs of the y value and the x value when you and that should tell you in what quadrant?
 
  • #6
198
18
I'm not sure what you're asking, if you use the vector form of Coulombs Law and keep the signs in on the charges then you get the magnitude of the resultant force as well as the direction (assuming you have defined an x and y axis). If you haven't been introduced to the vector form of the equation then what you have done is fine.
 
  • #7
272
0
I'm not sure what you're asking, if you use the vector form of Coulombs Law and keep the signs in on the charges then you get the magnitude of the resultant force as well as the direction (assuming you have defined an x and y axis). If you haven't been introduced to the vector form of the equation then what you have done is fine.
I mean like since the signs of both the charges are positive and since tan is opposite over adjacent ( .274/ .88) that would mean it is in the first quadrant since both the x and y values are the same
 
  • #8
198
18
Yes but remember there are two solutions to tan(positive number) - the first quadrant and the third. The charge of the test particle tells you which one it is.
 
Last edited:
  • #9
272
0
Yes but remember there are two solutions to arctan(positive number) - the first quadrant and the third. The charge of the test particle tells you which one it is.
What do u mean by that?
 
  • #10
198
18
I made an edit above. The force on q1 due to q2 is given by Coulombs law and for two like charges the direction of the force on q1 is in the direction of q2 to q1, i.e. repulsive. If you keep everything as vectors the right direction pops out of the equation.

Using the non-directional F = [itex]\frac{q1 q2}{k r^{2}}[/itex] you need to consider the geometry of the set up. No direction will pop-out.
 

Related Threads on How to determine angle of net force-electric charges of right triangle

Replies
5
Views
9K
  • Last Post
Replies
1
Views
2K
Replies
4
Views
5K
  • Last Post
Replies
1
Views
23K
Replies
4
Views
4K
  • Last Post
Replies
4
Views
2K
  • Last Post
Replies
3
Views
6K
  • Last Post
Replies
4
Views
17K
  • Last Post
Replies
2
Views
1K
  • Last Post
Replies
7
Views
1K
Top