A proton moves at 7.92 10 m/s along the x-axis. It enters a region in which there is a magnetic field of magnitude 2.90 T, directed at an angle of 60.0 with the x-axis and lying in the xy- plane (Fig 19.8). (a) Find the initial magnitude and direction of the magnetic force on the proton. (b) Calculate the proton's initial acceleration. te, 60 Figure 19.8 The magnetic force F on a proton is in the positive z-direction when and lie in the xy-plane.