Physics Question

audi

Banned
Jan 31, 2005
458
0
0
sorry guys, I have just not been able to work this physics question out. here's the problem:

Two small objects, A and B, are fixed in place and separated by 2.00 cm in a vacuum. Object A has a charge of +1.00 µC, and object B has a charge of -1.00 µC. How many electrons must be removed from A and put onto B to make the electrostatic force that acts on each object an attractive force whose magnitude is 45.0N?


I tried using Coulomb's Law: F = (KQ1Q2)/(r^2)

Knowing that the charge of the electron is 1.6 * 10^-19 and K is a constant of 8.99 * 10 ^ 9 I tried plugging the following in.

45=((8.99*10 ^ 9)(1*10^-6 + (1.6*10^-19)x)^2)/((.02)^2)

I solved this for X and got 7.95 * 10 ^ 22 when the back of the book says 2.6 * 10^12.

Could you please tell me where I'm going wrong, thanks.
 

Legendary

Diamond Member
Jan 22, 2002
7,019
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Edit: I'm an idiot - one sec - I learned this a long time ago and I might be able to remember it.
 

dighn

Lifer
Aug 12, 2001
22,820
4
81
your euqation looks right to me and from it i get the book answer of 2.59 x 10^12

u just did the calc wrong
 

audi

Banned
Jan 31, 2005
458
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0
Originally posted by: dighn
your euqation looks right to me and from it i get the book answer of 2.59 x 10^12

u just did the calc wrong

wow you're right, I did it 3 different times and got the wrong answer each time. :( thanks for the help