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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谢贡叶3813一辆在平直的公路上匀速行驶的垃圾车,动能和机械能会怎样 -
步弦昨18578457835 ______ 动能和机械能都增大. 垃圾车当然是在打扫卫生了,把垃圾装到车厢里,因此会让垃圾车的质量变大. 速度不变时,质量越大,动能越大. 机械能是动能和势能之和,因此机械能也是增大的.
谢贡叶3813飞船离开地面的过程中,速度越来越大,则此过程中动能怎么变化,机械能怎么变化? -
步弦昨18578457835 ______ 动能只和速度、质量有关这个过程中,质量不变,速度增大,则动能增大在远离地球的过程中,飞船的重力势能在增大,动能也在增大,则机械能肯定在增大咯
谢贡叶3813围绕地球运动的飞船它离地球越远 所受到的万有引力越小 动能越小 引力势能越大 机械能越大.这对吗 为什么 -
步弦昨18578457835 ______[答案] 飞船绕地球飞行时,机械能是不变的.机械能包含 引力势能 和 动能. 随着飞船离地球忽远忽近,只是 引力势能与动能二者之间互相转化,但总和是不变的.
谢贡叶3813围绕地球运动的飞船它离地球越远 所受到的万有引力越小 动能越小 引力势能越大 机械能越大.这对吗 为什么 -
步弦昨18578457835 ______ 飞船绕地球飞行时,机械能是不变的.机械能包含 引力势能 和 动能. 随着飞船离地球忽远忽近,只是 引力势能与动能二者之间互相转化,但总和是不变的.
谢贡叶3813一道简单的初三物理(关于机械能的)请教 -
步弦昨18578457835 ______ 没停呢,是那个瞬间.机械能=动能+重力势能重力势能相等,而动能=1/2mv^2速度越大动能就越大,所以乙的动能较大所以乙的机械能较大.
谢贡叶3813一道关于高中物理机械能的填空题物体由于运动而具有的能叫做(机械能).运动物体( )越大,( )越大,这种能就越大. -
步弦昨18578457835 ______[答案] (动能),(速度),(质量)
谢贡叶3813一个氢气球从地面上升,上升的速度越来越大,则它的重力势能______,动能______,机械能______. -
步弦昨18578457835 ______[答案] 气球加速上升,质量不变,速度变大,动能变大.质量不变,高度增加,重力势能增大.动能增大,重力势能增大,机械能增大. 故答案为:增大;增大;增大.
谢贡叶3813卫星离地面的高度越大,动能越小,引力势能越大,那总机械能增大吗? -
步弦昨18578457835 ______ 如果卫星在太空中只受到地球的万有引力,那么它的情况就与氢原子的能级问题是一样的,能级越高,氢原子的能量就越大. 分析:卫星是绕地球做圆周运动,如果没有其他外力(只受到万有引力),它的轨道就是一个,当卫星要到更高轨道时必须要有另外的力作用(获得能量),所以卫星所在的轨道越高,它的机械能越大.
谢贡叶3813一个飞机加速上升 它的动能和机械能怎么变 -
步弦昨18578457835 ______ 1、一个飞机加速上升,动能和机械能都变大.2、动能=1/2mv'2、重力势能=mgh、机械能=动能+势能;所以动能增加、重力势能增加、机械能变大.3、动能是物体由于作机械运动而具有的能.4、机械能是动能与势能的总和,这里的势能分为重力势能和弹性势能.我们把动能、重力势能和弹性势能统称为机械能.决定动能的是质量与速度;决定重力势能的是质量和高度;决定弹性势能的是劲度系数与形变量.机械能只是动能与势能的和.机械能是表示物体运动状态与高度的物理量.物体的动能和势能之间是可以转化的.在只有动能和势能相互转化的过程中,机械能的总量保持不变,即机械能是守恒的.
谢贡叶3813动能:物体由于______而具有的能叫动能.运动物体的______越大,______越大,动能就越大. -
步弦昨18578457835 ______[答案] (1)运动的物体能够做功,具有的能叫动能; (2)影响动能大小的因素是:质量和速度;质量越大,速度越大,动能就越大; 故答案为:运动;质量;速度.
