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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怀寿雁3238高中天体中如何判断某个卫星其动能与机械能的增减? -
蓝胜卸19535308311 ______ 判断 卫星 动能与机械能的增减方法如下. 人造卫星绕地球做圆周运动有引力势能和动能两种机械能,而要发生轨道变化的前提就是机械能的改变,因为只有向前或者向后喷射燃气才能变轨.这种改变分成总量(机械能)的改变和组分(引力势能和动能)的改变. 机械能E=(-GMm)/2R,所以R越大机械能越大. 动能Ek=GMm/2R,所以R越大动能越小. R越大势能Ep越大. 从能量角度分析,万有引力做负功,卫星势能增大,动能减小,速度减小.

怀寿雁3238怎么区分机械能和动能?我知道机械能是动能和势能的总和.很纠结.运动的物体具有动能,可是物体在运动时 -
蓝胜卸19535308311 ______ 俗点来说,一个物体与地面有一定高度才有势能啊

怀寿雁3238如何判断物体是否机械能,动能等守恒 -
蓝胜卸19535308311 ______[答案] 系统内只有弹力或重力做功或只有二者同时做功时机械能守恒. 根据Ek=mv²/2可得,对于同一物体,在保证机械能守恒的条件下,v不变即做匀速直线运动时动能守恒 希望对你有所帮助~有不懂的可以百度hi'我~

怀寿雁3238化学能 机械能 动能 怎么区分 -
蓝胜卸19535308311 ______ 机械能由动能和势能组成.一个物体的动能加上势能(包括重力势能和弹性势能),就等於它的机械能.

怀寿雁3238动能和机械能的区别?机械能包括了动能? -
蓝胜卸19535308311 ______[答案] 机械能包括动能,势能.动能还应该包括刚体运动的动能还有自身振动的动能等.要具体情况具体分析的.

怀寿雁3238关于物理机械能和动能怎么分辨
蓝胜卸19535308311 ______ 机械能着眼于能量的守恒 动能定理着眼于能量的变化 动能定理就是各力做的功的和等于动能的该变量. 注意:1.是各力做的功的和,不是合力做的功 2.各力包括内力和外力.不过在刚体的时候内力做功是0,而人起跳的过程就几乎全是内力做功,地面几乎不做功. 机械能守恒是指对有势能的系统,势能加上动能的数值为定值. 有势能的力比如弹簧的力,重力,万有引力...等等

怀寿雁3238动能、势能、机械能的关系怎样准确判断动能、势能、机械能的增减 -
蓝胜卸19535308311 ______[答案] 机械能包括动能和重力势能. 外力对物体做正功,物体动能增加.反之,动能减少. 重力对物体做正功,物体重力势能减少.反之,重力势能增加. 动能与重力势能和减少,则机械能减少.反之,机械能增加. 你的标题中,光说势能是很相当笼统的.因为势能...

怀寿雁3238怎样判断动能、势能、机械能增加或减少? -
蓝胜卸19535308311 ______[答案] 只有机械运动,没有热传递、摩擦之类的话,机械能是不会变的. 动能增加的就是势能减小的,势能增加的就是动能减小的

怀寿雁3238在做题时怎么辨别动能,势能,和机械能的变化? -
蓝胜卸19535308311 ______ 动能对应的就是合外力做功,只要合外力做正功,动能就增加,不做功,动能不变,做负功,动能减少.忌判断物体的速度{除非速度变化很明显,但考试中这是不太可能的},因为一般速度不好判断,且烦,易错,还要关注方向.势能是一个标...

怀寿雁3238动能 和机械能 的区别既然动能属于 机械能,那是不是 在填空中,只要能填 动能的地方都可以填机械能 -
蓝胜卸19535308311 ______[答案] 不是,所谓动能,其实就是一种状态量,这种状态是不考虑外界场对其作用的状态量.而机械能时在考虑到其动能、重力势能及弹性势能的状态下所具有的能量的总和.举个例子来说,一颗子弹射出后具有动能和重力势能,此时动能不等效于机械能.但...