The classic momentum transfer between balls question

[original]

Homework Statement

A 5.0-kg object has a velocity of 6.0 m/s, east when it explodes into two 2.5-kg objects.
After the explosion one of the objects has a velocity of 4.0 m/s at an angle of 50° north
of east. What is the magnitude and direction of the velocity of the other object after the
explosion

Homework Equations

P=MV

P(i) = P(f)

The Attempt at a Solution

P=2.5*4sin(50)

P(i) = 30
P(f) = 30

I got about 3.5m/s, at 48 degrees, which apparently is quite wrong.

 

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