What is the round of hygiene?
Rolling frictional resistance is smaller than sliding frictional resistance.
The wheel made of circular, axle in the center of the wheel, when the wheel in the ground when the axle away from the ground distance, it is always equal to the wheel radius so long. So the car mounted on the axle, the car sitting in the people, will be gently pulled by the car. Assuming that the wheel is a broken, has not rounded, the rim on a high one low, that is from the rim to the wheel center of the distance are not equal, then the car walk up, be sure to take your Head faint
