Coulomb's Law: Calculating the Force between Two Charged Balls

AI Thread Summary
The discussion revolves around calculating the force between two charged balls using Coulomb's Law. The charges are -2.6 nC and +1.2 nC, with a separation of 2.5 cm. The formula F = k * (Q1 * Q2)/r² is applied, where k is the electrostatic constant. A question arises regarding the notation "n" in nC, which is clarified to represent nano, or 10^-9. The size and material of the balls are deemed irrelevant for the calculation as they are assumed not to interfere when positioned 2.5 cm apart.
Drizzy
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Homework Statement



A small ball has been loaded so that its charge is -2.6 nC. Another similar ball has the charge +1.2 nC. The balls are located at the distance 2.5 cm from each other . With how much force do the balls attracts each other?

Homework Equations



F = k * (Q1 * Q2)/r2

The Attempt at a Solution



k = 8,99 * 109
Q1 = -2.6 n
Q2 = +1.2 n
r2 = 0,00252

F = 8,99 * 109 (-2.6 * 1.2)/0,00252
---------------------------------------------
This is what my book has written:

F = 8,99 * 109 (-2.6 * 10-9 1.2 * 10-9)/0,00252

So my question is: From where did they get 10-9?
 
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Drizzy said:

Homework Statement



A small ball has been loaded so that its charge is -2.6 nC. Another similar ball has the charge +1.2 nC. The balls are located at the distance 2.5 cm from each other . With how much force do the balls attracts each other?

Homework Equations



F = k * (Q1 * Q2)/r2

The Attempt at a Solution



k = 8,99 * 109
Q1 = -2.6 n
Q2 = +1.2 n
r2 = 0,00252

F = 8,99 * 109 (-2.6 * 1.2)/0,00252
---------------------------------------------
This is what my book has written:

F = 8,99 * 109 (-2.6 * 10-9 1.2 * 10-9)/0,00252

So my question is: From where did they get 10-9?
What do you think nC means?
 
It means how many electrons and atoms there is in the ball but how am I supposed to know how big the ball is and what material it is?
 
Drizzy said:
It means how many electrons and atoms there is in the ball but how am I supposed to know how big the ball is and what material it is?
milli, micro, nano, pico, ... ring a bell?

You shouldn't care about the ball size or material. The problem says they are small so you can assume that their exact dimensions can be ignored and won't interfere with your calculations. In other words, assume that they won't touch or overlap when they are set 2.5 cm apart.
 
oh yeah nano is 10-9 I thought n was the number of electrons in the object (lika a variable) but now I know what it is thank you for the help :)
 
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