天弘优配中考物理基础知识（五）:压强和浮力 Basic Physics Knowledge: Pressure and Buoyancy

中考物理基础知识（五）:压强和浮力

Basic Physics Knowledge for the Senior High School Entrance Examination (Part Five): Pressure and Buoyancy

李宏湖北省十堰市郧阳中学

Li Hong Yunyang High School, Shiyan City, Hubei Province

第九章压强-[中考物理基础知识]

Chapter 9: Pressure [Basic Knowledge of Physics for the High School Entrance Exam]

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54．影响压力作用效果的因素：（1）压力大小；（2）受力面积大小

展开剩余90%

Factors affecting pressure effects: Magnitude of force (pressure); Area of contact (surface area)

55．压强的计算公式：p=F/S

Pressure calculation formula:p=F/S (Pressure = Force per unit area)

56．液体压强的特点：

Characteristics of liquid pressure:

（1）液体内部朝各个方向都有压强；

Liquids exert pressure in all directions internally;

（2）在同一深度液体向各个方向的压强相等；

At the same depth, pressure is equal in all directions;

（3）在同种液体中，深度越深，液体压强越大；

In the same liquid, pressure increases with depth;

（4）在深度相同时，液体的密度越大，液体压强越大。

At the same depth, pressure increases with liquid density.

57．液体压强的计算：P＝ρgh

Liquid pressure formula:P=ρgh

液体的压强只与液体的密度和浸入液体的深度有关。

Liquid pressure depends only on liquid density ( ρρ ) and depth ( hh ).

58．证实大气压存在的实验：马德堡半球实验(证明大气压强的存在)。

Experiments confirming atmospheric pressure:Magdeburg hemispheres experiment (demonstrates atmospheric pressure existence).

测定大气压值的实验是：托里拆利实验。

1标准大气压为760mmHg,即1．013×105Pa。

Torricelli's experiment (measures atmospheric pressure).1 standard atmospheric pressure = 760 mmHg =1.013×10⁵Pa.

59．大气压与海拔高度的关系：大气压随高度的增加而减小。

Relationship between atmospheric pressure and altitude:Atmospheric pressure decreases with increasing altitude.

60．流体压强与流速的关系：在气体和液体中，流速越大的位置压强越小(伯努利原理)。

Relationship between fluid pressure and flow speed:In gases and liquids, faster flow speed results in lower pressure (Bernoulli's principle).

第十章浮力-[中考物理基础知识]

Chapter 10 Buoyancy - [Basic Knowledge of Physics for High School Entrance Examination]

61．浮力产生的原因：浮力是由液体（或气体）对物体向上和向下的压力差产生的。

Cause of buoyant force: Buoyant force is produced by the pressure difference between the upward and downward pressures exerted on an object by a liquid (or gas).

浮力的方向：竖直向上。

Direction of buoyant force: Vertically upward.

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62．阿基米德原理：浸在液体中的物体所受的浮力，大小等于它排开液体所受的重力。即F浮＝G排＝M排g=ρ液gV排。

Archimedes' Principle: The buoyant force acting on an object immersed in a liquid is equal in magnitude to the weight of the liquid displaced by the object. That is, F buoy =G displaced =ρliquid gV displaced .

注意：浸在液体中的物体所受的浮力只与液体的密度和排开液体的体积有关；浸没在液体中的物体所受的浮力与浸没的深度无关。

Note: The buoyant force on an object immersed in a liquid is only related to the density of the liquid and the volume of the displaced liquid; the buoyant force on an object fully submerged in a liquid has no relation to the depth of submersion.

63．轮船是利用漂浮的条件F浮＝G物来工作的。

Ships work by making use of the floating condition:F buoy =G object.

潜水艇是靠改变自身重力来实现上浮和下沉的。

Submarines achieve ascending and descending by changing their own gravity.

64．求浮力的几种方法：

Several methods for calculating buoyant force:

(1)称重法： F浮＝G－F拉

Weighing method: F buoy =G−F tension

(2)压力差法：F浮＝F向上－F向下

Pressure difference method: F buoy =F up −F down

(3)阿基米德原理法：F浮＝ρ液gV排

Archimedes' principle method: F buoy=ρ liquid gV displaced