(Solved): A particle of mass 8.15g and charge 81.8C moves through a uniform magnetic field, in a region w ...

A particle of mass $8.15\mathrm{g}$ and charge $81.8\mu \mathrm{C}$ moves through a uniform magnetic field, in a region where the free-fall acceleration is $-9.8\hat{j}\mathrm{m}/{\mathrm{s}}^2$ without falling. The velocity of the particle is a constant $17.1\hat{\mathrm{i}}\mathrm{km}/\mathrm{s}$, which is perpendicular to the magnetic field. What, then, is the magnetic field?