Calculating Boat's Speed After Package Throw

[chibichibi7554]

Homework Statement

A child throws, at 10 m/s, a 3.4 KG package, horizontally, from a boat. The boat weighs 60 kg and the child weights 20 kg. If the boat was initially at rest, what was it's speed, after the throw?

Homework Equations

mv+mv=mv+mv

The Attempt at a Solution

I am not sure, do you have to add in the boat and child weight together so it is

mv+mv=mv+mv
0+0=(3.4)(10)+(20+60)v
v=-.425

 

[cristo]

That's correct.

 

[chibichibi7554]

yay! thank you! this is the first time all year i know what i am doing