1. Applications of Coulomb’s Law
Physics 12

2. Coulomb Sample Problem
Three charges are arranged in a line; if the three charges are 15μC, -12μC and 18μC respectively. The distance between the first two charges is 0.20m and the second and third charges is 0.30m. What is the force experienced by the first charge?

3. Coulomb Sample Problem
What force is experienced by the remaining two charges?

4. Force (Vector) Addition
To add forces, resolve each force into its components and treat the forces in the x-direction and y-direction independently
Once you sum the x and y components, use Pythagorean Theorem and Trigonometry to resolve into a resultant force

5. Example
A point P has forces of 12.0N at 24.3°, 17.6N at 112°, 6.78N at 241° and 10.2N at 74.4°.
Determine the resultant vector
25.5N, 81.4°

6. Coulomb’s Law and Vector Addition
When we consider an electrostatic system, we need to use Coulomb’s Law to determine the magnitude and direction of each force
Once the magnitude and direction of each force has been determined, then the vector sum can be completed

7. Coulomb’s Law in 2D
Three charges are arranged as follows; a -2.0μC is placed 4.0m due north of a 3.0μC charge and 3.0m due west of a 5.0μC charge. What is the force experienced by the -2.0μC charge?

8. Coulomb’s Law in 2D
-2.0μC
5.0 μ C 1
3.0m 3
4.0m
3.0 μ C 2

9. Coulomb’s Law in 2D
3.0 μ C 2

10. Coulomb’s Law in 2D
Use the x and y component data to determine the resultant force vector

11. Practice Problems
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6-10
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