中考物理基础知识（六）: 功、机械能和简单机械
Basic Physics Knowledge for the Senior High School Entrance Examination (VI): Work, Mechanical Energy and Simple Machines
李宏 湖北省十堰市郧阳中学
Li Hong Yunyang High School, Shiyan City, Hubei Province
第十一章 功和机械能-[中考物理基础知识]
Chapter 11: Work and Mechanical Energy - [Basic Physics Knowledge for High School Entrance Examination]
展开剩余91%65．功的两个要素：
The two essential factors of work:
（1）作用在物体上的力；
The force acting on an object;
（2）物体在这个力的方向上移动的距离。
The distance moved by the object in the direction of the force.
66．功的计算：W=FS
Calculation of work: W=F⋅s
67．功的原理：使用任何机械都不省功。
Principle of work: No machine can save work.
68．功率的计算：（ W=Pt ）。功率的推导公式：P=Fv
Calculation of power: (W=P⋅t) 。The derived formula for power: P=F⋅v
69．物体由于运动而具有的能量叫动能，动能的大小与物体的质量和物体运动的速度有关，且运动速度对动能的影响较大。
The energy possessed by an object due to its motion is called kinetic energy. The magnitude of kinetic energy depends on the mass of the object and its velocity, with velocity having a greater impact on kinetic energy.
70．物体由于高度所具有的能量叫重力势能。
The energy possessed by an object due to its height is called gravitational potential energy.
重力势能的大小与物体的质量和物体被举起的高度有关。
The magnitude of gravitational potential energy depends on the mass of the object and the height to which it is raised.
71．物体由于发生弹性形变而具有的能量叫弹性势能。
The energy possessed by an object due to elastic deformation is called elastic potential energy.
弹性势能的大小与物体发生弹性形变的程度和物体的材料、性质有关。
The magnitude of elastic potential energy depends on the degree of elastic deformation and the material and properties of the object.
第十二章 简单机械-[中考物理基础知识]
Chapter 12: Simple Machines - [Basic Physics Knowledge for High School Entrance Examination]
72．一根硬棒，在力的作用下能绕着固定点转动，这根硬棒就是杠杆。
A lever is a rigid bar that rotates around a fixed point when force is applied.
支点：杠杆绕着转动的点；
Fulcrum: the point around which the lever rotates;
动力：使杠杆转动的力；
Effort: the force that causes the lever to rotate;
阻力：阻碍杠杆转动的力；
Resistance: the force that opposes the rotation of the lever;
动力臂：从支点到动力作用线的距离；
Effort arm: the perpendicular distance from the fulcrum to the line of action of the effort;
阻力臂：从支点到阻力作用线的距离。
Resistance arm: the perpendicular distance from the fulcrum to the line of action of the resistance.
73．杠杆的平衡条件：动力×动力臂＝阻力×阻力臂 即 F1L1＝F2L2
Lever equilibrium condition:
Effort × Effort arm = Resistance × Resistance arm, i.e., F1L1＝F2L2
74．杠杆的应用：
Applications of levers:
（1）省力杠杆：L1＞L2 F1＜F2 省力费距离；（钢丝钳、撬棒）
Effort-saving lever: L1>L2, F1<F2, saves effort but requires more distance (e.g., wire pliers, pry bar).
（2）费力杠杆：L1＜L2 F1＞F2 费力省距离；（镊子、筷子）
Effort-intensive lever: L1<L2, F1>F2, requires more effort but saves distance (e.g., tweezers, chopsticks).
（3）等臂杠杆：L1= L2 F1= F2 不省力、不省距离，能改变力的方向。（天平）
Equal-arm lever: L1=L2, F1=F2, neither saves effort nor distance but can change the direction of force (e.g., balance scale).
75．定滑轮的实质是等臂杠杆，可以改变力的方向；
A fixed pulley is essentially an equal-arm lever, which can change the direction of force.
动滑轮的实质是动力臂等于阻力臂2倍的杠杆，可以省一半的力。
A movable pulley is essentially a lever where the effort arm is twice the resistance arm, saving half the effort.
76．使用滑轮组时，滑轮组用几段绳子吊着重物，绳子自由端的拉力就是物重的几分之一。
When using a pulley system, the tension in the free end of the rope is a fraction of the weight of the load, depending on the number of rope segments supporting the load.
且物体升高“h”，则绳子自由端移动“s=nh”，其中“n”为绳子的段数。
If the load is raised by a height "h", the free end of the rope moves a distance "s = n h", where "n" is the number of rope segments.
77．机械效率：滑轮组的机械效率、斜面的机械效率
Mechanical efficiency: Mechanical efficiency of pulley systems, mechanical efficiency of inclined planes.
Explorer of Innovative Thinking
Author: Li Hong
Yunyang High School, Shiyan City, Hubei Province
February 6老牌配资平台, 2026
发布于：湖北省易云达提示：文章来自网络，不代表本站观点。
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