If a person jumps off of a boat with constant velocity, should the equation resulting from the law of conservation of momentum be (where 1 denotes the mass/velocity of the person, 2 denotes those of the boat, and f denotes a final velocity):
m1 * 0 + m2 * v2 = m2 * v2f + m1 * v1f
or
m1* 0 + m2 * v2 = (m2-m1) * v2f + m1* v1f
m1 * 0 + m2 * v2 = m2 * v2f + m1 * v1f
or
m1* 0 + m2 * v2 = (m2-m1) * v2f + m1* v1f