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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席静耐5054能量守恒定律是谁提出的 ? -
俟急妮18639494159 ______ 爱因斯坦

席静耐5054能量守恒定律是错的~谁发现了? 能引见下权威物理学家么? -
俟急妮18639494159 ______ 爱因斯坦相对论中的质能转换内容(E=mc^2)在一定程度上是冲击和否定了经典的能量守恒定律. 不过,现代的“能量守恒定律”指的是“质能守恒定律”,即将质量也看成能量的一种存在形式. 现代的能量守恒定律是完全正确的.

席静耐5054什么是机械能守恒?
俟急妮18639494159 ______ 只有在重力(或弹簧弹力)做功的情形下,物体的重力势能(或弹性势能)和动能发生相互转化,但总机械能保持不变. 机械能守恒的条件: (1)对某一物体若只受重力作用,则物体与地球组成的系统机械能守恒. (2)对某一物体除受重力外...

席静耐5054什么是机械能守恒 -
俟急妮18639494159 ______ 重力势能、弹性势能和动能之和称之为机械能. 在只有这几个能转换的情况下,可以实现机械能守恒,方法是,将一个物体或者将几个物体看做一个整体,再看初末两种状态,运用公式就可以解答一般的所有问题了

席静耐5054什么叫机械能守恒? -
俟急妮18639494159 ______ 机械能:重力势能、弹性势能和动能统称为机械能. 只有在重力(或弹簧弹力)做功的情形下,物体的重力势能(或弹性势能)和动能发生相互转化,但总机械能保持不变. 机械能守恒的条件: (1)对某一物体若只有重力做功,则物体与...

席静耐5054关于机械能守恒的问题 -
俟急妮18639494159 ______ 这个问题想全面了其实并不难,这道题实际上是,动能、重力势能、弹性势能三个相加不变,应是以地球、弹簧、小球三个物体组成的系统机械能守恒.以你举得例子来说,小球向下摆动并非 做圆周运动,弹簧给小球的拉力与重力的合力提供向心力. 随速度增加,所需向心力增大,拉力增大,弹簧伸长,重力势能减小,弹性势能增加,动能增加 系统机械能不变

席静耐5054伯努利定律的公式是什么? -
俟急妮18639494159 ______ p+1/2ρv2+ρgh=C.伯努利原理往往被表述为p+1/2ρv2+ρgh=C,这个式子被称为伯努利方程.式中p为流体中某点的压强,v为流体该点的流速,ρ为流体密度,g为重力加速度,h为该点所在高度,C是一个常量.它也可以被表述为p1+1/2ρv12+ρ...

席静耐5054外力对物体所做的功等于零时,机械能一定守恒吗?外力指的是哪些力呢 -
俟急妮18639494159 ______[答案] 机械能守恒指只在重力(或只在弹力)作用下物体的机械能在转化过程中总能量不变. 由于势能是物体由于相对于地球的位置而具有的能,所以势能是物体和地球组成的整个系统所具有的能.则重力是这个系统内的力,所以外力就是指除物体和地球...

席静耐5054弹簧振子为什么机械能守恒?
俟急妮18639494159 ______ 弹簧振子分两种,一种是水平放置的,就是我们课本上出现的,这种情况中,振子在运动过程中只有弹力做功,机械能守恒. 关于机械能守恒,课本上是说在只有重力做功时,机械能守恒,实际上应该是:在只有重力或弹力(指弹簧)做功时,物体的机械能守恒(此时物体的机械能包括动能+重力势能+弹性势能); 另一种是竖直放置的,在这种情况下,只有重力和弹力做功,仍然满足机械能守恒的.

席静耐5054求解高中物理,如图为啥机械能守恒,式子怎么列出来的 -
俟急妮18639494159 ______ 当某个过程中只有重力或者弹力做功是机械能守恒.这里只有重力做功,所以机械能守恒.设地面为势能零平面,初动能+初势能=末动能+末势能或者是整个过程中的动能变化量=势能变化量