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coriolis7 t1_jajr75p wrote

Reply to comment by Kear_Bear_3747 in NASA’s DART data validates kinetic impact as planetary defense method | DART altered the orbit of the asteroid moonlet Dimorphos by 33 minutes by mepper

Not exactly. Momentum is always conserved, but the kinetic energy is not. A fully elastic collision preserves kinetic energy, while a partially inelastic collision does not.

In both cases m1 x v1(initial) + m2 x v2(initial) = m1 x v1(final) + m2 x v2(final).

However, only in the fully elastic collision does the following hold: [m1 x v1(initial) + m2 x v2(initial)] / 2 = [m1 x v1(final) + m2 x v2(final)] / 2

It doesn’t matter if it’s in space, in a lab, or wherever.

I think what the above redditor was saying is that because the outer material was more loosely held, more of the material could be ejected. That ejected material has additional momentum. Even though the probe never bounced off (ie elastic collision) the ejected material made the collision act as partially elastic.

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workingdad83 t1_jaju14g wrote

Oh yeah. 2√(brdsrntreel)+2 carry the 4. See I can just push a lot of buttons too.

Joking. I know you are smarter than me, and I was lashing out. I'm sorry.

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coriolis7 t1_jak3dle wrote

Sorry about the formatting, it makes a lot more sense when you see it properly formatted. The unformatted above is kinda dry to the eye.

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