A child in a boat throws a 6.40kg package out horizontally with a speed of 10m/s. Calculate the velocity of the boat immediately after, assuming it was initially at rest. The mass of the child is 26.0kg and the mass of the boat is 45.0kg. Ignore water resistance. Relevant equations MV1 + MV2 = M(1+2)V(1+2) The attempt at a solution Im not sure what other equations to use. I think possibly [1/2(MVf^2) - 1/2(MVi^2)] + [(MGHf)-(MGHi)] though im not totaly sure about this. Could someone lead me in the right direction. Im not sure what goes where.