at time t$-0,$ and electron with kinetic energy $11$ keV moves through x$=0$ in the positive direction of an x axis that is parallel to the horizontal component of Earth's magnetic field. The fields vertical component is downware and has magnitude $68\mathrm{.}9$ uT$.($a$)$ what is the magnitude of the electron's acceleration in meters per second squared, due to the magnetic field? $($b$)$ what is the electron's distance from the x axis in centimeters when the elctron reaches coordinate x$=29$ cm$?$