(a) Sodium ions (Na+) move at 0.865 m/s through a bloodstream in the arm of a person standing near a large magnet. The magnetic field has a strength of 0.255 T and makes an angle of 30.0° with the motion of the sodium ions. The arm contains 150 cm3 of blood with a concentration of 2.50×1020 Na+ ions per cubic centimetre. If no other ions were present in the arm, what would be the magnetic force on the arm?

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anonymous · Answer

Thank you very much I actually got 660 N but with sig figures its all good but could you explain why your diagram points down instead of up, as I'm not very good at the diagrams and I would of pointed up 
Thank you
Leela