How does a combine (farm machine) take the kernels off of the cob of corn? --- Adam, Tacoma, Washington
A Combine is called a Combine because it combines several different machines into one. Typically a Combine contains a reaper (which cuts and collects the crop), a thresher (which separates the grain from the stalk or the cob) and a winnower (which cleans the grain). A Combine also normally has a big hopper to hold the grain, and a way to get the grain out of the hopper.
The Combine assumes that the grain, whether it is corn, wheat, oats or whatever, is very dry. The thresher then separates the grain by "threshing" it, or by beating the grain off the shaft or cob in a rotating cylinder or similar mechanism. For more info see: Video: Corn combine.