【英语时差8,16】自由落体运动(下)(在线收听) |
If you got this one wrong, don’t worry: almost everybody does. For some reason the out-and-then-down scenario seems more sensible to us. But let’s look at it again. Gravity is always pulling your car downward, even when it’s sitting still on the road. Send the car over a cliff and gravity doesn’t need any time to start acting. It’s already pulling, just as it was before you left the road. But in this case, the car also has a forward velocity. That velocity will indeed send it flying outward — but not at the expense of falling downward. The result is that your free-falling car will make a graceful arc in the air, moving both downward and outward at the same time. By the way, you had a parachute and dove out just in time. Close one. |
原文地址:http://www.tingroom.com/lesson/englishtimeover/335156.html |