Of course,the biggest difference between the two bills, and one likely to cause the most friction in House-Senate negotiations, involves the so-called "public option" or competing insurance the government would offer.

VOA: standard.2009.12.25

That means the force you're applying is cancelled by another force, which has got to be the force of friction.

意味着你施加在物体上的力被另一个力抵消了,这个力就是摩擦力

耶鲁公开课 - 基础物理课程节选

So force of friction is yet another force.

摩擦力就是另外一种力

耶鲁公开课 - 基础物理课程节选

The cattle are very thirsty at this point, the rains have not come yet, they need to get to the water points, and water points are dried up all along those regular migration routes, and that has been one of the causes of the friction."

VOA: standard.2010.03.23