题目
英语翻译
Under which of the following conditions is the magnitude of the average velocity of a particle moving in one dimension smaller than the average speed over some time interval?A.A particle moves in the +x direction without reversing.B.A particle moves in the -x direction without reversing.C.A particle moves in the + x direction and then reverses the direction of its motion.D.There are no conditions for which this is true.
Under which of the following conditions is the magnitude of the average velocity of a particle moving in one dimension smaller than the average speed over some time interval?A.A particle moves in the +x direction without reversing.B.A particle moves in the -x direction without reversing.C.A particle moves in the + x direction and then reverses the direction of its motion.D.There are no conditions for which this is true.
提问时间：2020-08-03
答案
在下列情况中,求问：相同时间内物体的平均速度小于平均速率的选项是（）
A.物体沿+x移动,不掉头
B.物体沿-x移动,不掉头
C.物体沿+x移动,然后掉头
D.上述都不对
选C.因为平均速度=位移/时间,平均速率=路程/时间.既然时间相同,那么不掉头的运动其|位移|=路程,而掉头运动,|位移|<路程,所以|平均速度|<平均速率.
A.物体沿+x移动,不掉头
B.物体沿-x移动,不掉头
C.物体沿+x移动,然后掉头
D.上述都不对
选C.因为平均速度=位移/时间,平均速率=路程/时间.既然时间相同,那么不掉头的运动其|位移|=路程,而掉头运动,|位移|<路程,所以|平均速度|<平均速率.
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