How to compare the magnitude of buoyancy, such as the same volume, the same depth or the same gravity, The exam is always bad and depressing

Hehe, this is not good! I'd better prepare it for you and my students!
About buoyancy
1. Buoyancy and its cause: an object immersed in liquid (or gas) is supported upward by liquid (or gas), which is called buoyancy. Direction: vertical upward; cause: pressure difference between liquid and object
2. Archimedes principle: objects immersed in liquid are subject to upward buoyancy, and the buoyancy is equal to the gravity of objects expelling liquid
That is, f floating = g liquid discharge = ρ liquid GV discharge
3. Buoyancy calculation formula: F floating = G-T = ρ liquid GV discharge = f upper and lower pressure difference
4. When the object floats: F floats = g object and ρ object, G object and ρ object

The length, basin area, annual runoff, width and depth of the Yangtze River are compared with those of other rivers in the world

The Yangtze River is the largest river in China, with a total length of 6300 kilometers and a total area of 1.8 million square kilometers. The annual average water inflow is about 960 billion cubic meters. In terms of the length of the main stream and the water inflow, the Yangtze River ranks third in the world
Tuotuo River, the upper source of the Yangtze River, comes from Geladandong snow mountain in Tanggula mountains on the southwest border of Qinghai Province. After passing through Dangqu, it is called Tongtian River. It flows to the south below Batang river mouth in Yushu county and to Yibin City in Sichuan Province, it is called Jinsha River. It is called Yangtze River from Yibin and Yangtze River from Yangzhou. The Yangtze River flows through Tibet, Sichuan, Chongqing, Yunnan, Hubei, Hunan, Jiangxi, Anhui, Jiangsu and other provinces, There are Yalong River, Minjiang River, Tuojiang River, Jialing River, Wujiang River, Xiangjiang River, Hanjiang River, Ganjiang River, Qingyi River, Huangpu River and other tributaries flowing into the East China Sea in Shanghai
The Yangtze River is located in the upper reaches of Yichang City, Hubei Province, with many rapids; the middle reaches of Yichang to the Hukou of Jiangxi Province, with developed meanders and many lakes (Poyang Lake and Dongting Lake are the largest); below the Hukou is the downstream, with a wide river and Chongming island formed by alluvial deposition. The Yangtze River is rich in water and water resources. In the high water period, ten thousand ton ships can reach Wuhan, and small ships can trace back to Yichang
The Yangtze River Basin is an area with dense population and prosperous economy in China
The Yangtze River is the most abundant River in China with 200 million kilowatts of water energy available for development. The navigation mileage of the main stream of the Yangtze River is more than 2800 kilometers, known as the "golden waterway"
From Fengjie, Sichuan to Yichang, Hubei, the Yangtze River is a majestic and precipitous section of the Three Gorges (Qutang gorge, Wuxia gorge and Xiling Gorge). The Three Gorges project, the world's largest water conservancy project, is located in Sandouping, the middle section of Xiling Gorge
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The Yangtze River is the largest river in China and one of the largest rivers in the world, with a total length of more than 6300 kilometers. It originates from the southwest side of Geladandong snow mountain, the main peak of Tanggula mountains on the Qinghai Tibet Plateau (33 ° 28 ′ n, 91 ° 08 ′ E). The main stream flows through 10 provinces, cities and autonomous regions, including Qinghai, Tibet, Sichuan, Yunnan, Hubei, Hunan, Jiangxi, Anhui, Jiangsu and Shanghai, and flows into the East China Sea, with a total length of 6300 kilometers, The total length of the Yangtze River should be 6403 km, ranking the third in the world. The river basin is between 24 ° 30 ′～ 35 ° 45 ′ N and 90 ° 33 ′～ 112 ° 25 ′ e, covering an area of more than 1.8 million square kilometers (excluding the Huaihe River Basin), accounting for about 1 / 5 of the total land area of the country. The annual water inflow to the sea is 1 trillion cubic meters, ranking the third in the world
The main stream of the Yangtze River has different names: from the source to dangqukou (called "Qu" in Tibetan), it is called Tuotuo River, which is the main source of the Yangtze River, with a length of 358 km; from dangqukou to Batang estuary in Yushu County, Qinghai Province, it is called Tongtian River, with a length of 813 km; from Batang estuary to Minjiang Estuary in Yibin, Sichuan Province, it is called Jinsha River, with a length of 2308 km; from Minjiang Estuary in Yibin to Changjiang Estuary, about 2800 km, which is commonly called Yangtze River, Among them, the section between Yibin and Yichang in Hubei Province is called "Chuanjiang" (the Three Gorges section between Fengjie and Yichang is also called "Xiajiang"), the section between Zhicheng in Hubei Province and Chenglingji in Hunan Province is called Jingjiang, and the section below Yangzhou and Zhenjiang in Jiangsu Province is also called Yangtze river. In the basin, plateau and mountainous area account for 65.6%, hilly area 24%, plain and lowland 10.4%
There are 48 tributaries of the Yangtze River with an area of more than 10000 square kilometers; there are 9 tributaries of Yalong River, Minjiang River and its tributaries Dadu River, Jialing River, Wujiang River, Yuanjiang River, Xiangjiang River, Hanjiang River and Ganjiang River with an area of more than 50000 square kilometers. Among them, Yalong River, Minjiang River, Jialing River and Hanjiang River have an area of more than 100000 square kilometers, and Jialing River has the largest area, about 160000 square kilometers
Most of the freshwater lakes in China are distributed in the middle and lower reaches of the Yangtze River
The upper reaches of the ice and snow are from Mt, The chumar river is the North source of the Yangtze River; the mulu Wusu river is the south source of the Yangtze River, which has a long flow and a large amount of water. According to the principle of "river source is only far away", the longest tributary Tuotuo River should be the main source of the Yangtze river. The section from Dangqu estuary to Yushu in Qinghai is called Tongtian River, which is 813km long and has a wide channel and slow flow, From Yibin to nanjinguan in Yichang, the river flows through the Grand Canyon of the mountainous area on the border between Sichuan and Hubei, From the west to the East, there are Qutang gorge, Wuxia gorge and Xiling Gorge, which are collectively referred to as the Three Gorges. The total length of the Three Gorges is 204 km. There are many rapids and steep beaches, and there is a great drop of river water, which has been called the natural danger of the Yangtze River since ancient times. The downstream section is about 1850 km long. The drop of river water is very small, and the water flow is slow, Especially the section from Zhijiang in Hubei to Chenglingji in Hunan, which was called Jingjiang in ancient times, is known as "nine winding ileum". Due to the slow flow speed and much sediment deposition, whenever the flood season comes, it is very easy to cause dike break and flood disaster. Since ancient times, it has been said that "the Yangtze River is in danger of Jingjiang". From Yichang to Wuhu, there are many lakes on both sides, Among them, Dongting Lake and Poyang Lake are the largest. Dongting Lake is the natural reservoir of the Yangtze River. After the river enters Jiangsu, it is blocked by the mountains and flows northeast around Ningzhen mountain. From below Zhenjiang River, it turns to Shunan and enters the delta area. The terrain is flat, lakes are scattered everywhere, and waterways are intertwined like a network. The river mouth is 80 kilometers wide, There are many scenic spots on both sides of the Yangtze River. Due to the long process, wide drainage area, fertile land and convenient irrigation, there are "land of abundance" in the middle reaches and "land of fish and rice" in the lower reaches. Although the cradle of the Chinese nation is in the yellow River Basin, according to historical records, after King Wu of Zhou conquered Yin, the territory reaches the Yangtze River Basin in the south, Since then, the Yellow River and the Yangtze River have become the focus of China's historical and cultural development. There are many famous cities along the river, such as Chongqing, Yichang, Wuchang, Nanjing, Shanghai, etc. Shanghai is the largest industrial and commercial city in China. There are many places of interest on both sides of the river, which are valuable materials for understanding Chinese history, as well as many myths and legends, It is a precious heritage of Chinese literature. Since ancient times, the main tributaries of the Yangtze River have been the main water transportation arteries in South China, which run from east to west and from north to south. The total length of the waterway is more than 80000 kilometers. 10000 ton ships can reach Nanjing, 3000 ton ships can reach Hankou, 1000 ton ships can reach Chongqing, and 500 ton ships can reach Yibin

Although people can't decide the length of their lives, they can expand the width, depth and breadth of their lives. Why?
What is the value of life?

Life and death, that is not what we can control, but the meaning of living depends on the individual, to recognize themselves, to be themselves, and to deeply realize the significance and value of their own existence

What's half and quarter and eighth and eighth

How many kilometers is one kilometer

1km / min = how many km / h

Child, what grade are you in? 60km / h

1km is equivalent to several kilowatts. Is km also the power unit of three-phase asynchronous motor?

Km can also be kilometers
Watt is the unit of power. 1kW = 1000W, 1MW = 1000kW, 1kmw = 1000MW
Generally speaking, three-phase asynchronous motor will not have so much power, up to MW level. You should be talking about the power of power station

How many M / S is 1km / h equal to
It's physical
What m / S is 10.8km/h?

Km to 3.6 meters on the line, my junior high school teacher said very effective

Solution: 1km / h = m / s, 1m / S = km / h
I know that for me, but I don't know why today. The more I look at this question, the more confused and depressed I will be. So I come to ask

1km=1000m,1h=3600s
Therefore, 1km / h = 1000m / (3600s) = 0.278m/s
1m/s=10^(-3)km/((1/3600)h)=3.6km/h

How to compare the magnitude of buoyancy, such as the same volume, the same depth or the same gravity, The exam is always bad and depressing