hey guys, i have been trying to work this problem out but for some reason, my answer is different from the books answer on the back.(adsbygoogle = window.adsbygoogle || []).push({});

the problem is as follow:

Two points charges of 30 nC and -40nC are held fixed on an X axis, at the origin and at X=72 cm, respectively. A particle with a charge 42 micro C is released from rest at X=28 cm. if the initial acceleration of the particle has a magnitude of 100 Km/s^2, what is the particle's mass?????

the way i was solving it:

let q1=30nC and q2= -40nC q3=42 Mic C X=72 cm

F13 = (8.99*10^9*(30*10^-9)*(42*10^-6))/(28*10^-2)^2= 0.144

F23 = (8.99*10^9*(40*10^-9)*(42*10^-6))/(44*10^-2)^2= 0.078

F12 = (8.99*10^9*(30*10^-9)*(40*10^-9))/(72*10^-2)^2=2.08*10^-5

so Fnet= -F13+F23+F12 and then F=ma so m=F/a.

Am i solving it incorrectly. Please Help. Thanks

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# Homework Help: Mass of a particle help please

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