Sodium ions (Na+) move at 0.794 m/s through a bloodstream in the arm of a person standing near a large magnet. The magnetic ?eld has a strength of 0.26 T and makes an angle 68.3? with the motion of the sodium ions. The arm contains 77.4 cm3 of blood (within the magnetic ?eld) with 2.56 × 10^20 Na+/cm3. If no other ions were present in the arm, what would be the magnetic force on the arm? (Note: In fact, many oppositely charged ions also ?ow in the bloodstream, so the net force is considerably smaller than the number you will calculate here.)