"We have been talking about Nigeria and we are going to go to Nigeria. It is a lot of words about moving,moving, but we are prepared to go to Nigeria.

VOA: standard.2009.10.22

In other words, you don't have to be moving actually in a circle to have the acceleration.

也就是说,你不必真的在一个圆上运动以获得相应的加速度

耶鲁公开课 - 基础物理课程节选