Net Force of Charges on an Equilateral Triangle

In summary, the problem involves three point charges with equal magnitudes, two positive and one negative, fixed to the corners of an equilateral triangle with sides of length 0.02m. Using the equation F = kQq / r^2, the magnitude of the net force for each charge can be calculated. To determine the direction of the net force, the rule that opposite charges attract can be used. Adding the vectors head-to-tail or using trigonometry can be used to determine the direction and magnitude of the net force at point A.
  • #1
theintarnets
64
0

Homework Statement


Three point charges have equal magnitudes, two being positive and one negative.
These charges are fixed to the corners of an equilateral triangle.
The magnitude of each of the charges is 2.9 µC.
The lengths of the sides of the triangle are .02m
Calculate the magnitude of the net force that each charge experiences.

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Homework Equations


The only equation my professor gave me was:
F = kQq / r2


The Attempt at a Solution


I used F = kQq / r2 to get F. I got 189 N, which I think should be the magnitudes of net force at points B and C. But I don't know what to do now to get point A. I tried using other formulas I found on the web, but they keep giving me the wrong answer. Help please?
 
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  • #2
A each corner, the charges will experience a force due to both the other two.
Recall that force is a vector.
 
  • #3
So what am I supposed to do? Fnet = F1 + F2, but where do the vectors come in? I'm not sure which ones should be negative or positive... How do I tell?
 
  • #4
You know a rule for which way two charges pull or push each other.
"Opposite charges _______________." (complete the sentence)

It's direction that's important - do you know how to add vectors?
 
  • #5
Opposite charges attract... I forgot how to add vectors... I saw one formula that multiplied by sin or cos. I assume I use sin if it's got a y component, cos if x. I'm sorry, my professor hasn't taught me a thing about this stuff, and I can't afford the textbook...
 
  • #6
You add vectors head-to-tail.
It's pretty unlikely that you are doing electrostatics without being given notes on how to do this but just in case:
http://www.mathsisfun.com/algebra/vectors.html
... you can draw scale diagrams for the vectors, or just sketch them out and use trigonometry (which is where the sines and cosines comes from). Lots of the lessons use coordinates - you don't need that for your homework.

If you look at it, A will be pulled equally by B and C ... so you know which direction the net force will end up.
The two forces are 60deg apart ... so, when you add them head-to-tail, you'll get an isosceles triangle with apex angle 120deg.
 

FAQ: Net Force of Charges on an Equilateral Triangle

1. What is the net force on a charge at the centroid of an equilateral triangle?

The net force on a charge at the centroid of an equilateral triangle is zero. This is because the forces exerted by the two other charges on the triangle cancel each other out due to the symmetry of the triangle.

2. How do the distances between the charges affect the net force on a charge at the centroid?

The distance between the charges does not affect the net force on a charge at the centroid of an equilateral triangle. As long as the triangle remains equilateral, the net force will always be zero.

3. Can the net force on a charge at the centroid of an equilateral triangle ever be non-zero?

No, the net force on a charge at the centroid of an equilateral triangle will always be zero due to the cancellation of forces from the other two charges on the triangle. This is a result of the symmetry of the triangle.

4. What is the direction of the net force on a charge at the centroid of an equilateral triangle?

The direction of the net force on a charge at the centroid of an equilateral triangle is also zero. This is because the forces from the other two charges on the triangle are equal in magnitude but opposite in direction, resulting in a net force of zero.

5. How does the magnitude of the charges affect the net force on a charge at the centroid of an equilateral triangle?

The magnitude of the charges does not affect the net force on a charge at the centroid of an equilateral triangle. As long as the charges are equal in magnitude, the net force will always be zero due to the symmetry of the triangle.

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