英语时差：坐旋转木马会头晕？

The next time you’re at a park, watch children playing on a merry-go-round and you’ll notice that kids sitting in the center of the merry-go-round don’t get as dizzy as those hanging on the edge. That’s because the inner ear helps you keep your balance, and when your inner ear is disturbed by a force such as spinning, you feel dizzy. Kids on the edge of the merry-go-round are experiencing greater force, and therefore are getting dizzier, than those at the center. Here’s why. Physics tells us that objects at rest want to stay at rest, and those in motion want to stay in motion, and when these objects are in motion, they naturally move in a straight line. To get an object to move in anything other than a straight line, you have to exert force on it. A force is required for an object to move in a circle, as is the case with a merry-go-round. This force is called a centripetal force.