(单词翻译:单击)
You're out on the golf course one pleasant afternoon.
在一个舒适的下午,你站在高尔夫球场上 。
Your ball is set on the tee.
把球在球托上放好,
You lean overthe ball.
身体倾斜到球的上方,
You grip the club just right.
握好球杆 。
Your arms are straight. Your stance perfect. Whoosh!
呼地一声!你挥杆了,高尔夫球飞了起来,
You swing, and the ball takes off toward the green, sailing in a beautiful arc–almost as if it's weightless.
奔向绿地,划出一道优美的弧线,轻盈得似乎没有重量 。
Your impeccable technique certainly has a lot to do with the success of that drive, but you got amajor assist from the little dimples on the golf ball-and they're the subject of this Moment ofScience.
这一杆的成功当然和你完美的技术密不可分,但高尔夫球上的那些小窝也帮了你的大忙,它们就是本期《科学一刻》的主题 。
Combined with the proper spin, the dimples help keep the ball in the air longer, and here's how.
如果加上适当的旋转,这些小窝可以帮助高尔夫球在空中停留更长时间,原因如下 。
Your picture-perfect swing puts back spin on the ball.
你完美的挥杆动作使球向后旋转 。
The dimples trap a layer of air next to theball, and this layer spins with the ball.
球上的小窝吸附了周围薄薄的一层空气,这层空气会与球一块旋转 。
The air being dragged across the top of the spinning ball moves in the same direction as the airthat's rushing past.
球所吸附的这层空气转到球的上方时,它的运动方向与周围空气流动方向一致 。
As the air spinning with the ball comes around the bottom it is moving in theopposite direction from the air on top, and therefore against the onrushing air.
而这层空气到球下方的时候,它的运动方向与上方空气相反,因此与周围气流相抵 。
Consequently it'sslower than the air on top.
这样就使得下方的空气的速度比上方的要慢 。
A slow moving air stream has higher pressure than a fast moving air stream.
速度慢的气流压强较大,速度快的气流压强较小 。
So, the higherpressure on the bottom of the ball is going to hold the ball up longer.
因此,球底部较高的气压可以把球向上托使它在空中驻留更长时间 。
The effect of the dimples is so significant that a drive of two-hundred yards hit with a dimpled golf ball, would be shortened with a non-dimpled ball to about one hundred yards.
这些小窝的作用是十分重要的,同样的一杆,如果可以把有小窝的高尔夫球击出200码,那它只能把没有小窝的球击出大约100码 。