Two equally charged particles, held 4.7 × 10-3 m apart, are released from rest. The initial acceleration of the first particle is observed to be 7.2 m/s2 and that of the second to be 7.0 m/s2. If the mass of the first particle is 6.4 × 10-7 kg, what are
(a) the mass of the second particle and
(b) the magnitude of the charge of each particle?