沪科版初级中学物理课本第一册第九章力和物体运动状态的变化的作业3(P148)第1题:“列车受到牵引力是2×10~5N.如果列车是匀速行驶,它受到的阻力是多大?如果列车的速度在增加,它受到的阻力一定小于多少?如果列车的速度在减小,它受到的阻力一定大于多少?”答案是:“如果列车匀速行驶,它受到的阻力是2×10~5N;如果列车的速度在增加,它受到的阻力一定小于2×10~5N;如果列车的速度在 Shanghai Normal University Middle School Physics Textbook Vol.1 No.9 Chapter 9 Changes in Force and Object Movements Homework 3 (P148) Problem 1: “The train is under traction of 2×10~5N. If the train is running at a constant speed, it is subject to How much resistance is it? If the speed of the train is increasing, how much resistance will it receive? If the speed of the train is decreasing, how much resistance will it receive? ”The answer is:" If the train runs at a constant speed, it receives The resistance is 2×10~5N; if the speed of the train is increasing, the resistance it receives must be less than 2×10~5N; if the speed of the train is