本题目来源于试卷: 2007美国US F=MA物理竞赛，类别为 美国F=MA物理竞赛
[单选题]
When the speed of a rear-drick)epdc9ho w :2 n7cxuv*68veve car is increasing o4hmr8w ife2kh6pz; p/n a horizontal road, the direction oh w48i;e fpz2rhmkp6/f the frictional force on the tires is
A. backward on the front tires and forward on the rear tires.
B. forward on the front tires and backward on the rear tires.
C. forward on all tires.
D. backward on all tires.
E. zero.
参考答案: A
本题详细解析:
The rear tires are the "drive" trx.blp5r po4c2 e a+*hires.
The engine causes them to rotate, and they push *backward* on the road.
By Newton's third law, the road exerts a *forward* static friction force on the rear tires, which accelerates the car.
The front tires are passive. As the car accelerates forward, the front tirespr. xha2pob5 ce4*+rl are "pushed" into rolling.
The road exerts a small *backward* frictional force (rolling friction, or static friction opposing the change in rotation) on them.
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