初中物理学过许多物理量的测量,如:长度、体积、质量等,这些物理量通常情况下用专用仪器可以直接测出。但有些特殊物体却又很难直接测量,需要采用一些特殊的“巧妙”方法才能够较准确的测出,下面介绍几种特殊情况下的测量方法。1化直法化曲为直,将弯曲的轨迹变成直线来测量。测量地图上铁道线的长度,可以用棉线与它重合,再拉直测量;测薄圆铁片的周长,可使铁片沿棉线滚一圈再测量起点和终点的长度;测量大树的直径可使棉线绕大树转一圈再放开拉直测量, Junior Physics has measured many physical quantities such as length, volume, and mass. These physical quantities can usually be measured directly with special instruments. However, some special objects are difficult to measure directly, and some special “ingenious” methods are needed to be able to measure them accurately. The following describes the measurement methods in several special cases. The straightening method is straight, and the curved trajectory is measured as a straight line. Measure the length of the railway line on the map. You can use cotton to coincide with it and then straighten the measurement. Measure the circumference of the round iron plate to make the iron plate roll along the cotton line and measure the length of the starting and ending points; measure the size of the tree. The diameter can make the cotton thread around the big tree and release the straight measurement.