Coulomb's Law (5 of 7) Force from Three Charges in a Straight Line

How to use Coulomb's law to calculate the net force on one charge from two other charges. Coulomb's law states that the magnitude of the force between two point charges is directly proportional to the product of the magnitudes of charges and inversely proportional to the square of the distance between them. If the sign of the charges is the same, both positive or both negative, then there will be a force of repulsion between the charges. If they have the opposite sign then there will be a force of attraction between the objects. The force is along the straight line joining the two charges. The SI unit for the force is the newton.

The force between the charged bodies at rest is commonly known as the electrostatic force. Coulomb's law is an inverse-square law and is similar to Isaac Newton's inverse-square law of universal gravitation, but gravitational forces are always attractive, while electrostatic forces can be attractive or repulsive.

The law is named after the French physicist Charles-Augustin de Coulomb who first discovered it in 1785. The SI unit for electric charge was named after him.

[cindypher]

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[bitaka]

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[sethnewell]

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[Deathenvious]

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[panparami]

When determining the direction of the forces, is F31 going to the right because -8 is greater than -16? I know that because both have negative charges, they are repulsive. I don't understand why it goes to the right. Does F32 go to the left because 6 is greater than -8?

[malamarkudi]

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[junaidhoosen]

Thank you, I find this lesson so easy. This will help me for the test tomorrow

[lanomusambazi]

Thank you sir. My question is, are attractive forces positive or negative? And does it mean that all vectors going to the right are positive and those going to the left negative? I'm really get confused on this part. Make me understand the concept here sir. I appreciate your videos are loud and clear. Give me a link so that I watch the whole series on coulomb's law. I thank you.

[donnaherrera]

My professor went over it briefly but this helped a lot! Thanks!!

[shawnyboy]

Been looking at the text book for an hour lost on the example they gave, thanks for the clear explanation !

[shun]

Thank you, very simple to understand and grateful that you explained every step.

[catecrutch]

I had no idea how to do this 15 minutes ago but now I understand! Thank you!

[nicolevolek]

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[anjalitomar]

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[nataliemcneeley]

Just stumbled along your video and it's helping me understand my class much more. Thank you so so so much for this video!

[cel.este]

If you were looking for the magnitude of this net force, would it give you a positive answer even though it would still be directed towards the left?
(I'm just confused with the signs)

[CaptainGeronimo]

Thank you very much, I have physics exam soon. I have a question, does this equation aply always ? Or does it change as we move one of charges ?

[REDRR]

Thank you!! what do I need to do to find the distance Q2 needs to be from Q1 to have a Fnet=0. In other words the distance for it to remain stationary.

[mehrdadshfee]

I have a question . Do we subtract the forces when they attract each other or do we add them up ?

[tammybush]

Just to be certain, would you get the same results if you calculated the Force from Q1, 2 and Q1, 3? In your video, you calculate the sum of the Forces of Q3, 1 and Q3, 2.