[填空题]
A child in a boat throws a 6.40-kg package out horizontally with *s:p89jcjk w sqqr)(ia speuu0clh4eg/vgx70 s 5rj4uan *ed of 10 m/s Fig. bel s jhl rv/e a4gugc0xu0*4un75ow Calculate the velocity of the boat immediately after, assuming it was initially at rest. The mass of the child is 26.0 kg, and that of the boat is 45.0 kg. Ignore water resistance. The velocity of the boat is m/s
