函数模型及其应用.ppt

1.如何构建合适的函数模型？ 思考、讨论： 请根据你得到的模型，试解释为什么《中华人民共和国道路交通安全法》规定：机动车在高速公路上行驶，车速超过每小时100公里时，安全车距为100米以上；车速低于每小时100公里时，最小安全车距不得少于50米？ 小结： 1.如何构建合适的函数模型？ 步骤： 1.画散点图 2.利用相关系数 判断模型的适用性 越接近于1，模型越合适。 3.写出函数解析式 2. 函数模型的应用 1. If the concentration of chlorine have been place at the beginning is m ppm, whats the concentration of chlorine after t hours? 如果一开始投入m ppm 氯，那么t hours 氯的浓度为多少？ 2.Use the results to find the concentration that would be needed at 8 am on a similar day to ensure that the chlorine concentration did not fall below 1.5ppm(parts per million) before 3 pm. 一开始需要投入多少浓度的氯，才能确保3pm 前氯的浓度不低于1.5ppm 3.What concentration would be needed at 8 am that the concentration did not fall below 1.5 ppm before 12 noon? 一开始需要投入多少浓度的氯，才能确保12 noon 前氯的浓度不低于1.5ppm 4.If two chlorine doses were used , one at 8 am and another at 12 noon, what concentrations would be needed at these times to ensure that the concentration did not fall below 1.5 ppm before 3 pm? 两次分别需要投入多少浓度的氯，才能确保3pm前氯的浓度不低于1.5ppm 5.What are the implications of your answers for the effective chlorination of pools at lowest cost? It is cheaper to use smaller does more frequently than larger does less often. 课堂检测 函数模型及其应用 1.下表是某种车的车速与刹车后的停车距离。 车速／km/h 10 15 30 40 50 60 70 80 90 100 停车距离／m 4 7 12 18 25 34 43 54 66 80 （1）根据上表数据，建立车速和刹车后停车距离间的函数关系。 你对高速公路管理部门有什么新的建议？ 2．Some Chemistry students measured the concentration of chlorine remaining in a swimming pool over a period of 8 hours on a hot summer day. Chlorine had been placed in the pool at 8 am. Their results were as follows. Morning Afternoon Time 9 10 11 12 1 2 3 4 Chlorine concentration(ppm) 5.0 3.8 2.9 2.2 1.6 1.2 0.9 0.7 a. Use the calculator to find the relationship between the chlorine concentration and the time elapsed since the chlorine was placed in the pool. b. What’s the concentration of chlorine had been placed at 8 am ? Let The concentration of chlorine had been placed is 6.72ppm Example．Some Chemistry students