It's often funny how creationists try to argue about physics, when they have absolutely no idea about physics. You get all kinds of vague references to different scientific theories (or, more precisely, to small parts of them) to try to argue for a certain claim. For example, some creationists try to argue for the reason why we see even the most distant galaxies by alluding to the general theory of relativity, and how time passes at different speeds depending on the strength of the gravity field. They have absolutely no understanding, nor care, what other (very visible) consequences there would be if the timescale difference between the solar system and the intergalactic space would be that great (the list of such consequences would be quite large, and most of them would be quite evident, and that's assuming we could actually live in such an environment) nor do they even understand how the speed of light in vacuum works.
But never mind that example. One less popular example, but one that's still claimed by several creationists, is that the flood of the Bible was caused by a gigantic ice meteor that crashed on the Earth and cooled it, caused the ice polar caps, and so on. This was one of the favorite hypotheses of the famous Kent Hovind (and it might still be, who knows.) Some other creationists are blindly repeating it.
There is so much wrong about this whole idea that it's outright amusing.
Just for starters, let's forget for a moment the actual collision, and let's just imagine that we place a mountain-sized ice meteor on the surface of the Earth. How much would it cool down the global temperature? I'll leave the calculations to someone else because I'm not a climatologist nor a physicist, but the effect would be quite minor. Nowhere even close to what Hovind is claiming (ie. from basically a worldwide tropical climate to the modern one, with ice caps.)
But that was only a minor thing. The major flaw in this whole thing is the infantile and naive thinking of "an ice meteor is cold, therefore it would freeze the Earth." This is like thinking that if I throw an ice cube at you at bullet speed, you will get colder.
It doesn't matter if the meteor is made of ice or rock. It will have a certain mass, and if it falls on Earth, it will release hundreds, if not thousands, of kilotons of energy. That's thermonuclear bomb quantities. And that's just for a smallish meteor of some metric tons of weight. Hovind is talking about an enormous ice meteor, like mountain-sized. Its impact with the Earth would release the energy equivalent to thousands and thousands of thermonuclear bombs, causing a worldwide inferno. Rather than cooling the Earth down, it would basically scorch it.