Two equally charged particles are held 3.8 10-3 m apart and then released from rest. The initial acceleration of the first particle is observed to be 5.0 m/s2 and that of the second to be 9.0 m/s2. The mass of the first particle is 6.3 10-7 kg. (a) What is the mass of the second particle? (b) What is the magnitude of the charge of each particle? For A, i got 3.5e-7, which is the correct answer. However,for B, i wasn't sure of what to do. Do you simply do Mass time Acceleration for each particle. Then add those together to get the F? After that, you would use F=kqq/r-squared?