In the movie Speed a speeding bus is shown jumping a long gap in the elevated freeway. The Mythbusters test the physics at 1/12 scale. In the TV show Grant writes an equation to find the scaled down ramp exit velocity, where supposedly one must compensate the small scale speed downward because gravity does not scale down. Let the big bus have mass M. The little bus has mass m = M/(12 x 12 x 12). If there is zero atmosphere (air density rho equal zero) I figure this does not effect the scale down study. The mass drops out of the equation. However the distance travelled is 1/12 so the ramp exit velocity needed to cross the gap need not be as large. I'll be looking closely at the scale down logic eventually, but figured I'd pose the challenge here for comment.