Coulomb's Law (Finding magnitude & direction of net force)

In summary, three positive particles with equal charges (+11.5 µC) are arranged in an equilateral triangle with a side length of 13.0 cm. The task is to calculate the magnitude and direction of the net force on each particle using the equation k*|q1||q2| / r2. One approach is to draw a free body diagram and consider the forces from q2 and q3. Assuming symmetry, the x values can be cancelled out and the y value can be solved for using the sine function. However, the incorrect value of 132 was used for the distance between the particles, resulting in an incorrect answer of .0122. Correcting this mistake should lead to the correct solution.
  • #1
csgirl504
18
0

Homework Statement



Three positive particles of equal charge, +11.5 µC, are located at the corners of an equilateral triangle of side d = 13.0 cm (Fig. 16-50).

Calculate the magnitude and direction of the net force on each particle.

Image is here: http://www.webassign.net/giancoli5/16-38alt.gif


Homework Equations



k*|q1||q2| / r2



The Attempt at a Solution



Solving for net force on Q1:
Ok, I drew a free body diagram. The force from q2 goes up and to right, q3 goes up and to left. I thought that since the x values will be the same due to symmetry, I could cancel them out and solve for the y value.

So, I can find one force and multiply by two since they will be the same.

I did 2 * { (9e9 * 11.5e-6 * 11.5e-6)/132 } * sin60

I multiplied by sin60 to get the y value.

My answer is coming out to be .0122, which is wrong. I'm not sure what I'm doing wrong. Can someone please explain? Thanks!
 
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  • #2
Check your units for d! :)
 

Related to Coulomb's Law (Finding magnitude & direction of net force)

1. What is Coulomb's Law?

Coulomb's Law is a fundamental law of physics that describes the relationship between the magnitude of electric charges and the distance between them. It states that the force between two charged particles is directly proportional to the product of their charges and inversely proportional to the square of the distance between them.

2. How do you calculate the magnitude of the net force using Coulomb's Law?

To calculate the magnitude of the net force, you need to know the charges of the two particles and the distance between them. Then, you can use the formula F = kq1q2/r2, where k is the Coulomb's constant (8.99 x 109 Nm2/C2), q1 and q2 are the charges of the two particles, and r is the distance between them.

3. What is the direction of the net force in Coulomb's Law?

The direction of the net force is always along the line connecting the two charged particles. If the charges are of the same sign (both positive or both negative), the force will be repulsive and will push the particles away from each other. If the charges are of opposite signs, the force will be attractive and will pull the particles towards each other.

4. How is Coulomb's Law related to electric fields?

Coulomb's Law is used to calculate the electric field between two charged particles. The electric field is a vector quantity that represents the force per unit charge acting on a test charge placed at a certain point. It is given by the formula E = F/q, where E is the electric field, F is the net force, and q is the test charge.

5. What are the units of measurement for the variables in Coulomb's Law?

The units of measurement for the variables in Coulomb's Law are:

  • Force (F) - Newtons (N)
  • Charge (q) - Coulombs (C)
  • Distance (r) - Meters (m)
  • Coulomb's Constant (k) - Newtons x meters squared per Coulomb squared (Nm2/C2)

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