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I'm currently trying to learn kinematics and I can't figure out what seems to be a basic problem. It is the following: An 1800 kg car brakes from 15 m/s to a stop in 3 seconds. What is the net force of friction on the tires?

If you could help describe how I could figure this out or give me hints I would be very happy. Thanks :D!

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1 回答 1

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SI 单位；

假设轮胎提供恒定的力，因此加速度是恒定的：

加速度 = (0-15)m/s/3s = -5m/s^2; 力 = 加速度 * 质量 = -5*1800 = -9000 牛顿

检查 1：加速度约为 -0.5g，因此力约为 -0.5*1800 千克 = -900 千克 = 大约 -9000 牛顿

检查 2：摩擦力约为汽车重量的一半，因此摩擦系数必须至少为 0.5，表格显示如果道路干燥，这是可能的

于 2018-04-09T14:20:39.823 回答