【英语时差8,16】物理学冲浪

A sailboat is powered by wind, a motorboat by gasoline, and a rowboat by whatever the rower had for breakfast. There's one water craft, however, that gets all its horizontal push from the downward pull of gravity alone. Is this some futuristic new type of boat? Not at all. It's the humble¹ surfboard, and we'll learn about the physics of surfing on today's Moment of Science. Surfing is a lot like riding a skateboard down a hill–with the added advantage that the hill is moving along with you! When a skateboarder rolls down a hill, she's letting gravity pull her downward. She gets all her horizontal motion as part of this gravitational bargain. Once she reaches the bottom of the hill, she can't coast anymore unless she climbs the hill again. Surfers don't need to climb their watery² hills. They simply wait on their boards for a wave to rise up beneath them. When they get near the top, they stand on their surfboard, then let gravity start pulling them down the watery hill of the wave. The key to successful surfing is to slide downhill at exactly the same speed the wave moves up beneath you. If you slide down too fast, you'll reach the bottom of the wave quickly and your ride will be over. If you slide down too slowly, the wave will outrun you. Imagine our skateboarder again, but instead of a regular hill there's a monstrous³ hundred-foot-tall mole⁴ pushing up the ground beneath her wheels. If she rolls downhill at the same rate the mole is pushing the dirt up, she'll stay at the same height above the ground--and be coasting downhill the whole time!

 

1 humble   

adj.谦卑的，恭顺的；地位低下的；v.降低，贬低

参考例句：

• In my humble opinion,he will win the election.依我拙见，他将在选举中获胜。
• Defeat and failure make people humble.挫折与失败会使人谦卑。

2 watery   

adj.有水的，水汪汪的；湿的，湿润的

参考例句：

• In his watery eyes there is an expression of distrust.他那含泪的眼睛流露出惊惶失措的神情。
• Her eyes became watery because of the smoke.因为烟熏，她的双眼变得泪汪汪的。

3 monstrous   

adj.巨大的；恐怖的；可耻的，丢脸的

参考例句：

• The smoke began to whirl and grew into a monstrous column.浓烟开始盘旋上升，形成了一个巨大的烟柱。
• Your behaviour in class is monstrous!你在课堂上的行为真是丢人！

4 mole   

n.胎块；痣；克分子

参考例句：

• She had a tiny mole on her cheek.她的面颊上有一颗小黑痣。
• The young girl felt very self- conscious about the large mole on her chin.那位年轻姑娘对自己下巴上的一颗大痣感到很不自在。