专题06 机械能守恒定律 能量守恒定律
目 录
01机械能转化及守恒的判断 2
考向一：机械能转化及守恒的判断 2
02 机械能守恒定律的应用 7
考向一：机械能的图像类问题 7
考向二：单个物体的机械能守恒 15
考向三：多个物体(系统)的机械能守恒 18
03能量转化及守恒定律的综合应用 20
考向一：能量转化及守恒定律的综合应用 20
考向四：涉及弹簧的能量问题 22
考向二：涉及板块、传送带的能量问题 33
01机械能转化及守恒的判断
考向一：机械能转化及守恒的判断
1．（2023·浙江·高考真题）一位游客正在体验蹦极，绑上蹦极专用的橡皮绳后从跳台纵身而下。游客从跳台下落直到最低点过程中（ ）
A．弹性势能减小 B．重力势能减小
C．机械能保持不变 D．绳一绷紧动能就开始减小
3．（2022·浙江·高考真题）神舟十三号飞船采用“快速返回技术”，在近地轨道上，返回舱脱离天和核心舱，在圆轨道环绕并择机返回地面。则（ ）
A．天和核心舱所处的圆轨道距地面高度越高，环绕速度越大
B．返回舱中的宇航员处于失重状态，不受地球的引力
C．质量不同的返回舱与天和核心舱可以在同一轨道运行
D．返回舱穿越大气层返回地面过程中，机械能守恒
5．（2021·浙江·高考真题）如图所示，同学们坐在相同的轮胎上，从倾角相同的平直雪道先后由同高度静止滑下，各轮胎与雪道间的动摩擦因数均相同，不计空气阻力。雪道上的同学们（ ）
A．沿雪道做匀速直线运动 B．下滑过程中机械能均守恒
C．前后间的距离随时间不断增大 D．所受重力沿雪道向下的分力相同
7．（2024·广东江门·统考模拟预测）蹦极是一项非常刺激的体育项目，而“反向蹦极”是一项比蹦极更加刺激的运动。如图所示，弹性轻绳上端固定在P点，下端固定在玩家的身上并向下拉长与固定在地面上的安全扣环相连。打开安全扣环后，玩家从c点开始由静止释放，像“火箭发射一般竖直向上运动”，上升到b点时速度最大，轻绳在a点为原长位置，玩家到达的最高点在P与a之间，不计空气阻力，下列说法正确的是（ ）
A．人在c到a运动过程中都做加速运动
B．人在c到b运动过程中做加速度减小的加速运动
C．在整个运动过程中，玩家的机械能守恒
D．人在b到最高点的运动过程中，玩家处于超重状态
8．（2024·广东惠州·统考二模）2023年10月3日，在杭州亚运会蹦床项目女子决赛中，中国选手朱雪莹夺冠，图为朱雪莹在东京奥运会上决赛时腾空后下落的照片，朱雪莹从刚接触床面到运动至最低点的过程中，下列说法正确的是（ ）
A．朱雪莹刚接触床面时速度最大
B．朱雪莹在该过程中始终处于失重状态
C．在该过程中朱雪莹的动能减少量等于弹性势能的增加量
D．在该过程中蹦床对朱雪莹一直做负功
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柴食金1643什么是机械能守恒?
戈罗尹17182746433 ______ 动力学中的基本定律,即任何物体系统如无外力做功或外力做功之和为零,系统内又只有保守力(见势能)做功时,则系统的机械能(动能与势能之和)保持不变.外力做功为零,表明没有从外界输入机械功;只有保守力做功,即只有动能和势能的转化,而无机械能转化为其他能,符合这两条件的机械能守恒对一切惯性参考系都成立. 这个定律的简化说法为:质点(或质点系)在势场中运动时,其功能和势能的和保持不变;或称物体在重力场中运动时动能和势能之和不变.这一说法隐含可以忽略不计产生势力场的物体(如地球)的动能的变化.这只能在一些特殊的惯性参考系如地球参考系中才成立.
柴食金1643人教版高一物理必修二机械能守恒定律知识点总结 -
戈罗尹17182746433 ______ 在只有重力或弹力对物体做功的条件下(或者不受其他外力的作用下),物体的动能和势能(包括重力势能和弹性势能)发生相互转化,但机械能的总量保持不变.这个规律叫做机械能守恒定律. E机=Ep+Ek 机械能守恒条件是:只有重力(或...
柴食金1643机械能守恒定律表达式 -
戈罗尹17182746433 ______ 机械能守恒定律: 只有重力做功的情况下,物体的动能和重力势能. 发生相互转化,但机械能保持不变 . 表达式: Ek1+Ep1=Ek2+Ep2 成立条件:只有重力做功.延展回答:机械能守恒定律(law of conservation of mechanical energy)是动...
柴食金1643什么是机械能守恒定理 -
戈罗尹17182746433 ______ 机械能守恒定理,指的是物体运动时只有动能和势能互相转化(显示不可能的,要在理想的无摩擦、无阻力状态下)机械能的总和不变.说简单点,在物体不受外力,运动时,它的机械能是不变的
柴食金1643机械能守恒定律的理解 -
戈罗尹17182746433 ______ 机械能守恒定律 1、动能和势能统称为机械能. 2、机械能守恒定律: ①在只有重力做功的条件下,物体的动能和重力势能相互转化,但机械能的总量保持不变. ②在只有弹力做功的条件下,物体的动能和弹性势能相互转化,但机械能的总量保...
柴食金1643机械能守恒定律
戈罗尹17182746433 ______ “只有重力做功”不等于“只受重力作用”.在该过程中,物体可以受其他力的作用,只要这些力不做功,就可以认为“只有重力做功”.机械能守恒定律的内容为:在只有重力(以及系统内弹力)做功的情况下,动能和势能可相互转化,但总机械能保持不变.
柴食金1643机械能守恒定律 -
戈罗尹17182746433 ______ 由系统守恒ΔEP=ΔEKmg(0.5πR-R)=0.5*2mv^2球A在最高点对柱面的压力mg-N=mv^2/RN=(2-0.5π)mg由牛三 N'=-N N'=(2-0.5π)mg方向竖直向下 望采纳
柴食金1643机械能守恒定律的概念是什么?
戈罗尹17182746433 ______ 在只有重力或弹力做功的物体系统内,动能与势能可以互相转化,而总的机械能保持不变 不过机械能守恒是由条件的 1 )只受重力或弹力2) 除重力或弹力外,其他力合力为0 (3)除重力和弹力外,其他力不做功 4)除重力和弹力外,其他力做功为0
柴食金1643有关机械能守恒定律 -
戈罗尹17182746433 ______ 确实没有外力做功,但是绝对没有哪个物理老师敢说没有外力做功的情况下系统的机械能守恒.这样说的老师是冒牌老师. 书上只有说在不受外力的情况下系统动量守恒.你说的例子符合这个规律. 没有外力做功的情况下,系统内部有其它的...
柴食金1643机械能守恒定律公式是什么? -
戈罗尹17182746433 ______ 过程式: 1.WG+WFn=∆Ek 2.E减=E增 (Ek减=Ep增 、Ep减=Ek增) 状态式: 1.Ek1+Ep1=Ek2+Ep2(某时刻,某位置) 2.1/2mv1^2+mgh1=1/2mv2^2+mgh2[这种形式必须先确定重力势能的参考平面] 机械能守恒定律(law of conservation of ...
