radius acceleration

例句：

1. 1. The circle has a radius of 5 units.
   这个圆的半径是5单位。
2. 2. The speed of the car is directly proportional to its radius.
   汽车的速度与其半径成正比。
3. 3. The planets revolve around the sun with their respective radii.
   行星围绕太阳以各自的半径运行。