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物理规律的表达方法,往往是用数学公式,但在解决实际问题、分析具体现象时,如果用图象法来讨论有时更形象、直观和简便。我们在教学中应用图象法来分析问题,同学感到实用、也容易理解,从以下几个例子可说明这一点。例一某物体从静止开始先以大小为a_1的加速度运动一段时间,紧接着又以大小为a_2的加速度作匀减速运动直到停止,若全部运动时间是t、则物体的总位移是多少? 解:如果全部用运动学公式计算,设第一段加速运动位移为s_1,时间为t_1。第二段匀减速运动位移为s_2,时间为t_2,减速前的即时速度为v。则可以列出一组方程:
The expression of physical laws is often based on mathematical formulas. However, in solving practical problems and analyzing specific phenomena, it is sometimes more visual, intuitive and simple to use image methods for discussion. We use the image method in teaching to analyze problems. Students feel practical and easy to understand. This can be illustrated by the following examples. Example 1 An object moves from a standstill to an acceleration of a_1 for a period of time, followed by a uniform acceleration of a_2 to a stop. If the total movement time is t, what is the total displacement of the object? : If all the kinematics formulas are used, set the first-stage acceleration movement to s_1 and the time to t_1. The displacement of the second stage of uniform deceleration is s_2, the time is t_2, and the instantaneous speed before deceleration is v. Then you can list a set of equations: