A proton [(mass= 1.67 \times 10^{-27} kg, charge = 1.6 \times 10^{-19} C)] travelling with [speed = 1.0 \times 10^6 m/s] enters a region of space containing a uniform magnetic field of [1.2 T]. What is the time t required for the proton to reemerge into the field-free region?

[t = ]

A charged particle of mass [m = 7.5 \times 10^{-8} kg], moving with constant velocity in the y-direction enters a region containing a constant magnetic field [B = 1.9 T] aligned with the positive z-axis as shown. The particle enters the region at [(x,y) = (0.5 m, 0)] and leaves the region at [(x,y) = 0, 0.5 m] a time [t = 481.0 \mu s] after it entered the region.

With what speed [v] did the particle enter the region containing the magnetic field?