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一、关于浮力的教学浮力是液体(或气体)对浸在它里边的物体的作用。为了使学生明确浮力及其产生的原因,我们事先布置了一个题目为“用细绳把一塑料正方体缚在橡皮筋下面,测出橡皮筋长度 l_1,然后把正方体全部浸没在水中,又测出该时的橡皮筋的长度 l_2。比较 l_1与 l_2的长度关系,从力的平衡的角度出发,想一想,这是什么原因?”的家庭实验。为浮力的教学作了准备。我们着重从三个方面来演示和讲授浮力。即浮力是什么样的力,浮力产生的原因是什么,以及为什么浮力的方向总是竖直向上的。有关浮力这一节的主要内容都是从演示实验引出的,因此,演示实验尤为重要。我们在演示浮力的存在时,先把金属块挂在弹簧秤上,请学生读出弹簧秤的示数。再引导学生应用已学
1. The buoyancy of buoyancy is the effect of a liquid (or gas) on an object immersed in it. In order to make students understand the buoyancy and its causes, we pre-arranged a topic entitled “Tighten a plastic cube with a string under the rubber band, measure the length of the rubber band l_1, then immerse the cube in the water, and then measure it. The length of the rubber band at that time is l_2. Compare the length relationship between l_1 and l_2, and from the perspective of force balance, think about what is the reason?" The home experiment. Prepared for buoyancy teaching. We focus on demonstrating and teaching buoyancy from three aspects. What is the force of buoyancy, what is the cause of buoyancy, and why the direction of buoyancy is always vertical. The main content of the section on buoyancy is derived from demonstration experiments. Therefore, demonstration experiments are particularly important. When we demonstrate the existence of buoyancy, we first hang the metal block on the spring scale and ask the students to read out the scale of the spring scale. Re-direct student applications learned