density
1 density: the mass per unit volume of the substance.
2 Density = mass/volume
The density of a substance is related to the substance itself, and has nothing to do with mass and volume. Different substances usually have different densities.
Density represents a characteristic of matter itself [affected by temperature]
⑴ Attribute: It has nothing to do with external factors.
⑵ Features: Influenced by some factors.
The unit of density is kg/m3.
5 density water =1g/cm3 =1000 kg/m3.
Physical meaning: The water quality per 1 m3 is 1000 kg.
The density of gas is less than that of liquid and less than that of solid.
The same substance, with different attitudes, will have different densities.
At present, the densest star found in the universe is a neutron star.
Pressure and pressure
1 pressure: the force acting vertically on the surface of an object and pointing to the surface is called pressure.
The direction of pressure is always perpendicular to the stress plane.
The deformation effect produced by pressure is determined by the pressure on the unit stress area of the object.
When the contact area is the same, the greater the pressure, the more obvious the effect of pressure.
When the pressure is the same, the smaller the contact area, the more obvious the effect of pressure.
The difference between pressure and gravity
Gravity pressure at different points
The direction is vertically downward and perpendicular to the compression surface.
The center of gravity of the action point presses on the surface of the object.
Symbol G F
The gravity is proportional to the mass and depends on the deformation between objects.
Define the force acting vertically on the surface of an object due to the gravity of the earth.
6 Pressure: The pressure per unit area of an object is called pressure.
7 pressure = pressure/stress area p=F/S
In the international system of units, the unit of pressure is Pascal, and the symbol of Pa for short is PA.
The pressure of an adult on the ground is 10000Pa.
Physical meaning: the pressure per 1 m2 is10000 n.
10 reducing the pressure or increasing the stress area can reduce the pressure.
1 1 Increasing the pressure or decreasing the stress area can increase the pressure.
12 ultimate pressure: Experience shows that all materials have a limit to the pressure they can bear, and once the pressure exerted on the materials exceeds this limit, the materials will be destroyed.
The pressure inside the liquid
1 liquid has no certain shape and is mobile.
The liquid exerts pressure on the bottom of the container [the liquid is acted by gravity] and the side wall [the liquid has fluidity].
There is pressure in all directions in the liquid, and at the same depth, the pressure in all directions is equal.
Tool for measuring internal pressure of liquid: U-tube manometer.
5 What factors are related to liquid pressure?
⑴ Depth: In the same liquid, the deeper the depth, the greater the pressure.
⑵ Density: At the same depth in different liquids, the liquid with high density produces strong pressure.
⑶ Height difference: judge whether there is liquid pressure.
6 formula: p= density * mass * depth
communicating vessels
1 Communicator: It consists of several containers with communicated bottoms and communicated upper openings.
So as to keep the liquid level in the communication equipment level.
(1) same liquid
(2) After the liquid is still.
Sphygmomanometer: A device that uses a U-tube manometer to measure human blood pressure.
Archimedes'principle
1 Archimedes principle: when an object is completely or partially immersed in a liquid, it will be subjected to upward buoyancy, which is equal to the gravity that displaces this part of the liquid.
Factors affecting buoyancy: the density of liquid increases and the buoyancy increases.
The volume of an object immersed in a liquid increases and its buoyancy increases.
2 F float [buoyancy of an object immersed in liquid ]= G row[ gravity of the displaced liquid]
3 G row =M row *g = liquid density *V row *g
4 F float = liquid density *V rows *g
The cause of buoyancy is the pressure difference between the upper and lower surfaces of the object.
F floating =F upper surface -F lower surface.
The direction of buoyancy is always vertical upward.
6 the ups and downs of objects
G is greater than f, and the density of sinking liquid is greater than that of object.
G=F [at rest in any position] The density of the suspended liquid is equal to the density of the object.
F is greater than g [immersion], and the density of floating liquid is less than that of object.
Archimedes principle also applies to the buoyancy of objects in air.
8 displacement refers to the mass of the ship when it is fully loaded.
9 liquid densimeter: the scale is from top to bottom, and the value is from small to large.
10 the method of changing the ups and downs of an object: change its own volume and change its buoyancy.
Method of changing buoyancy: change the density of liquid [gas] and change the immersed volume.
1 1 V float /V total = object density/liquid density.
12 If the object floats, it is immersed in1/nObject density =1/nLiquid density.
history
2007 Sichuan Education Edition Ninth Grade World History Review (Part Two)
World War I (1914.7 ——1918.1) (8-12 pages)
1, the root cause of the outbreak of the First World War: the imbalance of political and economic development in capitalist countries has caused major changes in the balance of power among countries.
Direct cause: Sarajevo incident1965438+In June 2004, Serbian youth Pusipolin shot and killed Ferdinand, the heir of Austria-Hungary in Sarajevo, the capital of Bosnia and Herzegovina in the Balkans. This incident became the fuse of World War I.
The symbol of the beginning of World War I: 19 14.7 Austria-Hungary declared war on Serbia.
Views on similar terrorist incidents such as assassination: We must resolutely oppose terrorist activities such as assassination. It is a serious threat to world peace and security, so we should attach great importance to it and be vigilant, and we should not regard assassins as national heroes. )
2. The warring parties in World War I were three-way alliance, two major military confrontation groups and three-country agreement.
The focus of the struggle between the two major military blocs is the Balkans, which is also the powder keg of the world war.
3. The turning point of World War I: The Battle of Verdun was the decisive battle in World War I.. It happened on the western front of Europe, and the warring sides were Germany and France; People call it "meat grinder", "slaughterhouse" and "hell" Since then, Germany has lost the initiative to fight on the western front.
4. The result of the First World War
End:1918165438+10. In October, World War I ended in the defeat of the Allies.
Nature of War: It is an unjust and predatory war for world hegemony.
Impact (Consequence): On the one hand, the world war has brought unprecedented catastrophe to mankind and great disaster to the participating countries. The war lasted for four years, involving 65.438+0.5 billion people in more than 30 countries, with 30 million casualties and 34 million economic losses.
On the other hand, the war promoted the formation of independent Asian and African countries and the awakening of colonial people. In the later period of the war, the October Revolution broke out in Russia, and the world's first socialist country, Soviet Russia, was established. (the greatest achievement)
5. Would the First World War have happened without the Sarajevo incident? Why?
A: Without the Sarajevo incident, the First World War might not have happened. Because: the outbreak of war is not inevitable. Although the outbreak of the First World War had its profound historical reasons and complicated international background, if there had not been an incident like the Sarajevo incident that posed a serious threat to world peace and security, the contradictions between countries might have been resolved through peaceful and rational means, then the First World War might not have happened. )
Revelation: (or how do you feel about studying World War I? )
A: War is cruel. We must resolutely oppose hegemonism and colonialism, oppose war and safeguard world peace and tranquility. Dealing with international disputes through the Five Principles of Peace. (reasonable)
Petrograd Uprising (12-33)
1.1917165438+1On the evening of October 6, Lenin secretly came to the Smirny College of Petrograd Uprising Headquarters to lead the uprising. The cruiser Aphrodite launched an empty shell as a signal to attack the Winter Palace. 165438+1On October 7th, the Petrograd armed uprising won. The People's Committee of the Soviet government led by Lenin was established, and the first socialist country in the world was born.
2. Historical significance of the October Revolution: The Russian October Revolution was the first socialist revolution to win in human history. The first socialist country in the world was born. The victory of the October Revolution dealt a heavy blow to imperialist rule, promoted the development of the international socialist movement and inspired the liberation struggle of the colonial and semi-colonial people. Mao Zedong: "The October Revolution brought us Marxism–Leninism with artillery." )
3. Achievements of Soviet socialist construction: two five-year plans were completed ahead of schedule; Realize the transformation from an agricultural country to an industrial country; Comprehensive national strength has been greatly improved.
The formation of the Versailles-Washington system (pages 43-46)
1, Treaty of Versailles: 19 19 1. In order to conclude a peace treaty, the victorious allies made arrangements for the post-war world. It was the Paris Peace Conference that held the meeting in Paris. Twenty-seven countries attended the meeting, including French Prime Minister Clemenceau and British Prime Minister Lloyd. George and American President Wilson manipulated. On June 9th, the Allies signed the Treaty of Versailles with Germany. Main contents: Territory: Alsace and Lorraine were recovered by France; Military: Germany prohibits compulsory military service and air force. The number of the army shall not exceed 65,438+10,000, and Germany shall not be fortified within 50 kilometers east of the Rhine; Politics: Germany recognizes and respects the independence of Austria, Poland and the Czech Republic; Indemnity: The Allies set up an Indemnity Committee to decide the total amount of German war reparations; Colonies: All overseas colonies of Germany were divided up by countries such as Britain, France and Japan.
2. G-9 Meeting: At the initiative of the United States, representatives of the United States, Britain, France, Japan, Italy, the Netherlands, Belgium, Portugal and China held a meeting in Washington. The United States, Britain and Japan played a major role in the Washington Conference. 1922, representatives of nine countries signed the nine-nation convention China. Main contents: It claims to respect China's sovereignty, independence and territorial integrity, and abides by the principle of "open door" in China and "equal opportunities" among countries. Impact: It actually facilitated the expansion of the United States in China. Mao Zedong: "The Washington Conference brought China back to the situation where several imperialist countries ruled together. " ")
3. Versailles-Washington system:1965438+In June 2009, at the Paris Peace Conference, the Allies signed the Treaty of Versailles with Germany. From 19 19 to 1920, the allies also signed a series of peace treaties with Germany's allies Austria, Hungary, Turkey and Bulgaria. Together with the Treaty of Versailles, these peace treaties constitute the Versailles system and establish a new order for imperialism to rule Europe, West Asia and Africa. The Washington Conference is a continuation of the Paris Peace Conference, which established the ruling order of imperialism in East Asia and the Pacific. Through the Paris Peace Conference and the Washington Conference, the imperialist powers established the Versailles-Washington system. Essence: It is the system of imperialism to carve up the world again. Understanding: Because it only temporarily adjusts and eases the relations between imperialist powers, it is impossible to eliminate the contradictions between imperialist countries, so it cannot be maintained for a long time.
4. New international pattern after World War I: Through the Paris Peace Conference and the Washington Conference, the imperialist powers established the Versailles-Washington system, which constituted a new international pattern after World War I. ..
5. How to understand that the Versailles-Washington system cannot last long?
The Versailles-Washington system is the result of the re-division of the world by post-war imperialist countries. Because the victorious country plundered the defeated country, it intensified the contradiction between the defeated country and the victorious country; Due to the uneven distribution of spoils, the contradiction between the victorious countries has further intensified; In addition, the plundering of colonial and semi-colonial people by victorious countries also intensified the contradiction between colonial people and colonists. Therefore, this system has not fundamentally eliminated the contradictions between imperialist countries, nor can it be maintained for a long time.
Question and answer,
1 why did Mao Zedong say that the Washington conference brought China "back to the situation where several imperialist countries ruled together"?
The nine-nation convention signed at the Washington Conference ostensibly claimed to respect China's sovereignty, independence and territorial integrity, but actually affirmed China's semi-colonial status. Because it claims to "open the door" to China and give foreign forces "equal opportunities" in China. This broke the Japanese monopoly of China in World War I, and facilitated the invasion and expansion of the United States in China and the invasion of China by several other big countries. China was the biggest victim of the arrangement of the Washington Conference.
2. How to understand and evaluate the Versailles-Washington system?
The Versailles-Washington system established the post-war imperialist world peace order, but this order was extremely unstable. Because it not only did not eliminate the contradiction between imperialist countries, but deepened the contradiction between defeated countries and victorious countries. First of all, the Versailles system did not firmly control Germany, but aroused Germany's great hatred for the victorious country. Although Germany has some unfavorable factors such as territorial loss, military restrictions and reparations, it is still a powerful country in terms of potential. Secondly, the Washington system failed to effectively restrain Japan, which continues to step up its aggression against China and is ready to compete with the United States one day.
6. What's the difference between the Paris Peace Conference and the Washington Conference in terms of time, place, country of manipulation and areas involved?
The time and place of the project control the areas involved in the country.
Paris Peace Conference 19 19 France Paris Britain France America Europe West Asia and Africa
Washington Conference 192 1~ 1922 Washington, the United States, Britain, Japan, East Asia and the Pacific.
1929- 1933 Great Economic Crisis (48-49 pages)
1929 ~ 1933 Great economic crisis: 1929 started in the United States and quickly swept the whole capitalist world. Features: wide coverage; The duration is relatively long; Especially destructive. Impact: First, workers are unemployed, the life of working people is deteriorating, and social contradictions are deepening; Second, capitalists destroy goods and production is damaged. The serious economic crisis has triggered a political crisis, with sharp social contradictions and political turmoil in capitalist countries. Bourgeois in all countries are looking for a way out: the United States implemented Roosevelt's New Deal, and Germany, Italy and Japan embarked on the fascist road. Enlightenment: China's economic construction should not blindly pursue too high and too fast economic growth, but should have a long-term vision, devote itself to the sustainable development of the national economy and pay attention to improving people's living and consumption levels.
Roosevelt's New Deal: 1933 (49-5 1)
Background: 1929~ 1933 economic crisis triggered political crisis. Objective: To adjust within the capitalist system and strengthen the state's intervention and guidance in the economy, so as to eliminate the economic crisis. Content: Financially, rectify the banking industry; In terms of industry, (central measures) the adjustment of industry and the promulgation of the Industrial Revival Law; In agriculture, reduce agricultural output and stabilize agricultural product prices. Impact: The New Deal has achieved remarkable results. The American economy has slowly recovered and people's lives have improved; The capitalist system has been adjusted, consolidated and developed; The macro-control and management of the economy in capitalist countries have been strengthened; The power of the American federal government has been significantly enhanced. The New Deal is of great significance in the history of capitalist development in the United States and the world. Experience and lessons: implement fiscal and monetary policies, reduce savings interest rates and start projects to expand domestic demand, stimulate consumption, promote production, replace work with relief, and expand employment. Enlightenment: Roosevelt's New Deal initiated the capitalist countries to intervene in the economy, and became the basis for many developed and developing countries to formulate policies and regulations, indicating that the modern capitalist system has the function of self-adjustment and perfection. Evaluate the role of Roosevelt's New Deal in the history of capitalist development. )