A proton moves with velocity v$=(4+3)106$ m$/$s in a magnetic field B$=(0\mathrm{.}5)$T$.($a$)$ Determine the force on the proton, both magnitude and direction. $($b$)$ If the proton remains in the field, what the radius of curvature of its path? $($c$)$ What is the angular frequency of its motion?