【英语时差8,16】跳伞的科学依据（下）

Why not? She has reached what’s known as “terminal velocity¹.” This is when the upward push of air resistance–or the friction² she experiences as she falls through the air–is enough to exactly counterbalance the force of gravity. When she first jumped out of the plane, this upward push was negligible. At over a hundred miles per hour, it’s pretty strong. She’ll continue downward at a steady velocity, until she opens her chute.

1 velocity   

n.速度，速率

参考例句：

• Einstein's theory links energy with mass and velocity of light.爱因斯坦的理论把能量同质量和光速联系起来。
• The velocity of light is about 300000 kilometres per second.光速约为每秒300000公里。

2 friction   

n.摩擦，摩擦力

参考例句：

• When Joan returned to work,the friction between them increased.琼回来工作后，他们之间的摩擦加剧了。
• Friction acts on moving bodies and brings them to a stop.摩擦力作用于运动着的物体，并使其停止。