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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萧颖转4463物体做匀速直线运动,什么情况下机械能守恒? -
毕月和18071132389 ______[答案] 在只有重力或只有弹簧的弹力,或者是只有重力和弹簧的弹力做功的情况下机械能守恒. 也有可能是有其他力做功,但其他的力的合力做功为0,这样的情况下机械能也是守恒的,可以根据机械能守恒定律来解题.
萧颖转4463物体在什么情况下机械能守恒? -
毕月和18071132389 ______ 只有重力或弹力做功,或有外力但外力的和为零
萧颖转4463做圆周运动的物体机械能什么时候守恒,什么时候不守恒? -
毕月和18071132389 ______[答案] 机械能包括动能和势能,只要在只有重力存在的条件下,物体机械能是一直守恒的,即没有外力如摩擦力或空气阻力等,要是存在这种力,那机械能就不守恒了.
萧颖转4463机械能在什么情况下是不变滴? -
毕月和18071132389 ______[答案] 222你也是高一的?我们才刚刚学.我来告诉你~!在只有重力做工的情况下,物体的动能和重力势能发生相互转化,而总的机械能不变.这个结论叫做机械能守恒定律.譬如说,物体做自由落体运动,它整个过程只有重力做工(空气中的阻力忽略不记)...
萧颖转4463机械能守恒定律适用于哪些运动情况 能不能仔细解释下 -
毕月和18071132389 ______[答案] 只有动能和重力势能的情况下,机械能守恒.别的要从整体上看才行,它主要是适用于一个运动物体
萧颖转4463机械能守恒的条件
毕月和18071132389 ______ 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还受其他力作用,但只有重力做功,其他力不做功,则物体与地球组成的系统机械能守恒. (3)若某一物体受几个力作用时,只有弹簧弹力做功,其他力不做功,此时物体与弹簧组成的系统机械能守恒. (4)若某一物体受几个力作用时,只有重力和弹簧弹力做功,其他力不做功,此时物体、弹簧和地球组成的系统机械能守恒.
萧颖转4463机械能守恒条件 -
毕月和18071132389 ______ 只有重力 或 弹力做功 ,而且是系统机械能守恒. 一般做题的时候好多事机械能不守恒的,但是可以用能量守恒, 比如说把丢失的能量给补回来.
萧颖转4463机械能在什么条件下守恒 -
毕月和18071132389 ______ 只有外力做力,或者说内力做功为零
萧颖转4463机械能守恒是什么意思?什么情况下机械能守恒? -
毕月和18071132389 ______ 就是能量不会凭空消失和出现,没有外力的情况下机械能守恒.
萧颖转4463什么时候机械能增大减小或不变? -
毕月和18071132389 ______[答案] 机械能守恒的条件是只有重力做功,机械能不变.如有除重力以外的力做正功,则机械能增加,如做负功,机械能减少.
