北师大版高中数学选择修读2—2第4章节“定积分”定积分的简单应用[二]定积分在物理中的应用演示课件.ppt

* * * 定积分在物理中应用 Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 例2、 一点在直线上从时刻t=0(s)开始以速度v=t2-4t+3 (m/s)运动,求: (1)在t=4 s的位置; (2)在t=4 s运动的路程. ,t=4s时刻该点距出发点4/3m (2) t=4s时刻运动的路程为4 Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 例3 列车以72 km/h的速度行驶,当制动时列车获得加速度a=-0.4 m/s2,问列车应在进站前多长时间,以及离车站多远处开始制动? 解:列车速度v0=72km/h=20m/s,设列车由开始制动到经过t秒后的速度为v,则 ,令v=0,得t=50(s) 设列车由开始制动到停止时所走得路程为S,则 Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 练习: A 、B两站相距7.2km,一辆电车从A站开往B站,电车开出t s后到达途中C点,这一段速度为1.2t (m/s),到C点速度达24 m/s,从C点到B站前的D点以等速行驶,从D点开始刹车,经过t s后,速度为(24-1.2t)m/s,在B点恰好停车,试求: (1)A、C间的距离; (2) B、D间的距离; (3)电车从A站到B站所需的时间. (1)240 (m) (2)240 (m) (3)20+20+280=320(s) Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 1、如果1N能拉长弹簧1cm,为了将弹簧拉长6cm,需做功（ ） A. 0.18J B. 0.26J C. 0.12J D. 0.28J 所以做功就是求定积分 则由题可得 。 略解：设 A 说明：物体在变力F(x)的作用下做直线运动，并且