Your heartbeat, the pushing of a lawn mower, a baseball speeding through the air, water falling onto a waterwheel, the prying up of a rock with a crowbar-all are mechanical energy,which,of course,was another form of energy earlier.

• 你的心脏跳动、推进割草机、棒球在空中高速飞过、水落入水轮机、用撬杠撬开石头等等，所有这些都是机械能，当然，在转化之前它是另一种能量形式。