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Don't forget that the total vector force on a particle equals the vector sum of the forces from all other particles.
For an unconstrained particle not to move, the total force on the particle must equal the zero vector.
Hold Still Please
Age 16 to 18
Challenge Level 
Don't forget that the total vector force on a particle equals the vector sum of the forces from all other particles.
For an unconstrained particle not to move, the total force on the particle must equal the zero vector.
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