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## Homework Statement

One likely theory for the origin of the Moon is that it was formed by the impact of a Mars-sized object on the young Earth. How fast would the object have to be going when it hit the Earth to vaporize enough rock to make the Moon?

## Homework Equations

## The Attempt at a Solution

I know I need to make several assumptions for this problem, and that its very conceptual and that as of now the numbers aren't what are important.

I think I'm going to assume that the Earth is only made out of one substance, so that would mean the moon is made out of the same (maybe have it be iron? or silica?)

I think I'm going to need the heat of vaporization of that substance. I think I'll need to know how far away the moon is from the Earth and how large the moon, Mars and Earth is. I believe I'll need to know an estimated temperature of the mars-like object? (room temp??)

Those are all assumptions I need to make but the question is how to piece them together to get the angular velocity of the object coming at earth.

Maybe work backwards to it? Find the distance of the moon to earth, and the size of the moon and know that that big of a chunk must have been rocketed that far from Earth (what equations to get that though?) Moving farther backwards, I'll have to find the heat of vaporization necessary to melt and dis-attach something the size of the moon from Earth and moving even farther backwards from there I can find its angular velocity?

I'm confused as to where to start with this problem and also what equations to use. Numbers aren't important initially, I can compute those later...