1.5科学验证：机械能守恒定律课件-2021-2022学年高一下学期物理鲁科版（2019）必修第二册

1.5科学验证：机械能守恒定律 高一物理 鲁科版必修二2019 《鲁科版物理必修2（2019）》 高一物理组 导入新课 为什么小球好象记着自己的位置不会碰到鼻尖？ 演示实验：碰鼻子实验 Life is not about waiting for the storm to pass, its about learning to dance. <鲁科版必修2> Life is not about waiting for the storm to pass, its about learning to dance. (1)物体沿光滑斜面下滑时 转化为 。 V (2)运动员撑杆跳的过程中 转化为 。 (3)反弹后的小球在上升过程中 转化为 。 重力势能 动能 动能 弹性势能 弹性势能 动能、重力势能 动能和势能之间可以相互转化 1.机械能 Life is not about waiting for the storm to pass, its about learning to dance. <鲁科版必修2> Life is not about waiting for the storm to pass, its about learning to dance. 机械能（ ）：物体具有的动能和势能之和 思考：动能与势能的相互转化存在何种定量关系？ 1.机械能 重力势能EP 弹性势能EP 动能Ek 势能 机械能 动能 Life is not about waiting for the storm to pass, its about learning to dance. <鲁科版必修2> Life is not about waiting for the storm to pass, its about learning to dance. h1 h2 1 2 h 情景一：只受重力作用 做自由落体运动的小球 1、根据动能定理 2、根据重力做功 V1 V2 1.机械能守恒定律 Life is not about waiting for the storm to pass, its about learning to dance. <鲁科版必修2> Life is not about waiting for the storm to pass, its about learning to dance. 思考：两个式子的含义？ 动能增加 △EK 重力势能减少 △EP 初态机械能 E1 末态机械能 E2 物体只受重力作用，动能和重力势能可以相互转化，而总的机械能保持不变。 1.机械能守恒定律 Life is not about waiting for the storm to pass, its about learning to dance. <鲁科版必修2> Life is not about waiting for the storm to pass, its about learning to dance. 1.机械能守恒定律 小球沿光滑曲面下滑 mg FN h1 h2 情景二：除重力之外还受其他力，但只有重力做功 分析：下滑过程中支持力做功？ 重力势能变化？ 动能变化？ 0 物体只受重力作用，动能和重力势能可以相互转化，而总的机械能保持不变。 Life is not about waiting for the storm to pass, its about learning to dance. <鲁科版必修2> Life is not about waiting for the storm to pass, its about learning to dance. 1.机械能守恒定律 思考：除重力之外，有其他力做功时，机械能会守恒吗？ 设小球在下落过程中的空气阻力不可忽略 W总=WG+Wf EK2-EK1 EP1-EP2 EK2+EP2=EK1+EP1+Wf E2=E1+Wf （Wf<0） 根据动能定理 机械能不守恒 Life is not about waiting for the storm to pass, its about learning to dance. <鲁科版必修2> Life is not about waiting for the storm to pass, its about learning to dance. 1.机械能守恒定律 2 1 v1 v2 情景三：只有弹力做功 1、根