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Electric Force between glass ball and rubber ball

  • Thread starter Zokudu
  • Start date
  • #1
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Homework Statement



What is the electric force between a glass ball with 3.5 µC of charge and a rubber ball with -5.0 µC of charge when they are separated by 5 cm?

Homework Equations



Colombs Law:
F(electric)=K((q(1)*q(2))/r^2)
K=8.99E9

The Attempt at a Solution



This seems like a simple plug in problem but I'm having a little trouble.

First i get the elementary charges of both the glass and rubber balls
so 1.6E-19*3.5=5.6E-19 for q(1)
and 1.6E-19*5=8E-19 for q(2)

So i plug in the numbers i know and get:
F(electric)=8.99E9(((5.6E-19)*(8E-19))/(.005^2))=-1.611E-22

I plug this into the program my school uses for physics homework and it tells me im wrong.

Can you see where im doing something wrong? please any help is appreciated.
 

Answers and Replies

  • #2
hage567
Homework Helper
1,509
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First i get the elementary charges of both the glass and rubber balls
so 1.6E-19*3.5=5.6E-19 for q(1)
and 1.6E-19*5=8E-19 for q(2)
I don't understand why you did this. All you need to do is convert the 3.5 from microcoulombs to coulombs. Coulombs is the unit for charge.

F(electric)=8.99E9(((5.6E-19)*(8E-19))/(.005^2))=-1.611E-22
5 cm is not equal to 0.005 m. Check your conversion again.
 

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