Asteroid Hits Earth Conservation of angular momentum

[FahimP]

Homework Statement

the Earth has a n angular speed of 7.272 x 10 ^ -5 rad/s in it;s rotation. Find the new angular speed if an asteroid ( m = 1.17 x 10 ^ 22kg) hits the Earth while traveling at 1.41 x10^3 m/s.
the asteroid hits the Earth dead center

Homework Equations

The Attempt at a Solution

(La)f + ( Le) f = ( La) + (Le)i
Wf( MaR + 2/5MeR^2) = maRV + 2.5MeR^2W
Wf = ( MaVa + 2/5MeRWe) / ( Ma + 2/5MeR)

this is what I have as final angular speed but it gives me an answer faster than the Earth's initial angular momentum when the books answer is slightly less than the Earth's initial answer.

 

[Doc Al]

What's the angular momentum of the asteroid before the collision?

 

[Delzac]

Hmmm, just my own question. Does the direction of the rotation matter?

Delzac