An electron with a speed of 8 x 106 m/s is projected along the positive x-direction into a medium containing a uniform magnetic flux density B = (x4 _ z3) T. Given that e =1.6 x 10 –19 C and the mass of an electron is me = 9.1 x10 –31 kg, determine the initial acceleration vector of the electron (at the moment it is projected into the medium).