Circles and PiRadians Distance

Can you see that, in this example, radians are a much more convenient unit than degrees? Once we know the speed of rotation, we simply have to multiply by the radius to get the actual speed.

Here is another example: your car has wheels with radius 0.25 m. If you’re driving at a speed of 20 m/s, the wheels of your car rotate at 200.25=8020×0.25=50.2550=0.0125 radians per second (or 802π=13 rotations per second).