英語時差：自由落體運動（上）

Here’s a hypothetical scenario that is to remain hypothetical. In other words, don’t do this. Ok!You’re cruising along a desert highway in your souped-up roadster, leaving the roadrunners in the dust. Unfortunately, you are not paying attention to the signs and zoom off the edge of an enormous mesa. Now here comes the physics. When you left the edge of the mesa you were moving forward at sixty miles an hour. It seems pretty clear your car will continue moving out for a considerable distance before falling. But wait a minute, is that right? The answer is NO. You begin falling the instant your car leaves the mesa, no matter how fast it’s travelling.