The direction of friction on the front and rear wheels is () (A) The friction of the front and rear wheels are backward, (b) the friction of the front and rear wheels are forward, (c) the friction of the front wheel is backward and the friction of the rear wheel is forward, (d) the friction of the front wheel is forward and the friction of the rear wheel is backward

The direction of friction on the front and rear wheels is () (A) The friction of the front and rear wheels are backward, (b) the friction of the front and rear wheels are forward, (c) the friction of the front wheel is backward and the friction of the rear wheel is forward, (d) the friction of the front wheel is forward and the friction of the rear wheel is backward

Because the pedal drives the rear wheel to rotate and roll forward, the place in contact with the ground moves backward relative to the ground. According to the concept of friction, the direction is opposite to the direction of relative motion, so it moves forward. The front wheel is not the driving force, but it still rolls forward, indicating that it has received the force, and the place in contact with the ground moves backward, indicating that the ground gives