一、教学目标(1)通过“提水桶”“拉单杠”等生活情境,学生可以体会到生活中很多时候可以用一个力等效地替代几个力。学生在建立合力与分力、力的合成等概念的过程中,感受“等效替代”这一物理思想方法。(2)利用实验探索互成角度的两个共点力的合成规律,得出力的合成的平行四边形定则。理解矢量与标量的不同运算法则。(3)利用平行四边形定则作图法,求不同角度时共点力的合力。学生将能够理解平行四边形定则,并会应用 First, the teaching objectives (1) through the “bucket” “pull the horizontal bar ” and other life situations, students can realize that many times in life can be a force equivalent to replace several force. Students in the process of establishing the concept of synergy and force, synthesis of force, feel the “equivalent alternative” of the physical thinking method. (2) Using the experiment, we explore the synthesis law of the two co-forces between each other, and derive the parallelogram principle of force synthesis. Understand different algorithms for vectors and scalars. (3) The use of parallelogram method for mapping, seeking different points of total force together. Students will be able to understand the rules of parallelogram and will apply