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(单词翻译:双击或拖选)
You're driving along on your way to deliver some helium balloons to a birthday party. Suddenly you hit the brakes. As your car rapidly decelerates, you feel yourself pushed up against the wheel. Why? That one's probably not too tough. Although you may think you are sitting still when driving, your body is moving forward at the same speed as the car itself. So, when you hit the brake the car slows down but your body is still trying to go forward. You experience a sensation something like being pressed against the front of the car.
Think for a second. The car is going forward and abruptly2 stops. Which direction do the balloons go?
Surprisingly, if you've ever had this experience you might have noticed that the balloons move backwards3 -- just the opposite of your body. Why?
It's because the balloons are floating in the air that fills the car. The air itself is subject to the same acceleration4 as your body. When you hit the brakes, the air continues moving forward the same way you do. More air gets pushed to the front than remains5 in the back. So there is momentarily greater air pressure at the front of the car. The floating balloons register this by being pushed backwards.
点击收听单词发音
1 trickier | |
adj.狡猾的( tricky的比较级 );(形势、工作等)复杂的;机警的;微妙的 | |
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2 abruptly | |
adv.突然地,出其不意地 | |
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3 backwards | |
adv.往回地,向原处,倒,相反,前后倒置地 | |
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4 acceleration | |
n.加速,加速度 | |
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5 remains | |
n.剩余物,残留物;遗体,遗迹 | |
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6 tilt | |
v.(使)倾侧;(使)倾斜;n.倾侧;倾斜 | |
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7 briefly | |
adv.简单地,简短地 | |
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