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physgrl
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Homework Statement
1. Charge q1= 1.00*10^-9C is located +0.01 m from the origin along the x-axis. Charge q2= 2.00*10^-9C is located +0.03 m from the origin. What is the electric force exerted by these two charges on a third charge, q3= 1.5*10^-9C, located at the origin?
a. 1.65*10^-4N
*b. 1.4*10^-4N
c. 4.4*10^-4N
d. 6.1*10^-4N
Homework Equations
F=kq1q2/r^2
Ftotal=F1+F2...Fn
The Attempt at a Solution
both charges q1 and q2 exert a repelling force in the same direction with different magnitudes on charge q3
Ftotal=Fq1+Fq2
Ftotal=kq1q3/r1-32+kq2q3/r2-32
Ftotal=kq3((q1/r1-32)+(q2/r2-32))
Ftotal=9x109*1.5x10-9(1.0x10-9/(.01)2)+(2.0x10-9/(.03)2))
Ftotal=1.65x10^-4
the answer key says it is supposed to be B but I get A...what am I doing wrong?