1. The problem statement, all variables and given/known data This is third and last part of a question whose first part was solved on here earlier. Given the spin angular momentum of the Earth and the Orbital (around Earth) angular momentum of the moon calculate the mass of an object that if it hit the Earth at it's radius (glancing hit) would create these two momentums. 2. Relevant equations L=RxMV L=Iw I=2/5 MR2 3. The attempt at a solution I've gotten a final solution but just want to run the idea behind it to see if my logic makes sense. The calculation of the spin momentum of the Earth was just L=Iw where w=2[itex]\pi[/itex]/P. P is just the period of Earth's spin in seconds. I added that momentum to the moon's orbital momentum given by RxMV where R is the distance from moon to earth and v=1000 m/s and of course the mass was that of the moon. I added these two momentums together and set them equal to a new L. Then I just used the L=RxMv equation again with R= the radius of Earth and v the escape velocity of Earth (this was from the previous discussion and is correct). I found the mass to be 8.25(10)21 kg. I expected a mass similar to the moon and this is what I got (minus an order of magnitude). Does this seem like the correct approach? Thanks for the help. I can add the math but my question is more about method than calculations.