Calculation of buoyancy pressure in the second year of junior high school 20 calculation problems about buoyancy pressure I will add 20 points after answering

1. What is the volume of 1 m3 ice after melting into water? Does it increase or decrease? (ρ ice = 0.9 × 103 kg / m3)
2. Among the metal materials, osmium has the highest density of 22.5 g / cm3, while lithium has the lowest density of 0.534 g / cm3?
3. The weight of an empty bottle is 50g, the total weight is 1.3KG when it is filled with water and 1.05kg when it is filled with a certain liquid
4. The mass and volume of the shot put used in physical education class are measured to be 4kg and 0.57dm3 respectively. Can we judge whether the shot is made of pure lead? (the density of lead is 11.3 × 103kg / m3)
5. There is a bundle of copper wires with a cross-sectional area of 2.5 mm2 and a mass of 89 kg. The length of the bundle of copper wires can be calculated without a ruler. (ρ copper = 8.9 × 103 kg / m3)
6. A bottle can hold 1kg of water. How many kg of edible oil can be held in this bottle? (ρ edible oil = 0.9 × 103kg / m3)
7. The maximum carrying capacity of a car is 30 tons, and its volume is 40 m3. Now it needs to transport steel and wood. The density of steel is 7.9 × 103kg / m3, and the density of wood is 0.5 × 103kg / m3. How can these two materials be combined to make full use of the car?
8. A hollow aluminum ball weighs 27g. After its hollow part is filled with alcohol, the total mass is 43g. What is the volume of the ball? (ρ alcohol = 0.8 × 103kg / m3, ρ aluminum = 2.7 / 103kg / m3.)
9. The two objects are stacked as shown in the figure. The small bottom area of object a is 20 cm2, the large bottom area is 60 cm2, and the weight is 20 n. object B is a cube with a side length of 5 cm, which is placed on a horizontal plane
10. Two identical bricks, the gravity is 19.6n, the length of three edges is 20cm, 10cm, 5cm respectively. Brick a is placed horizontally, brick B is placed side by side, and the two bricks are overlapped as shown in the figure. The pressure of brick a on brick B is calculated
11. The maximum pressure that the frozen river ice can bear is 4 × 104 Pascal. The mass of a crawler tractor is 5200 kg. The total contact area between the two crawlers and the ground is 1.5 m2. Can this tractor pass through the ice?
12. The cube aluminum block with side length of 10 cm (ρ aluminum = 2.7 × 103 kg / m3) is placed on the horizontal table with side length of 50 cm, and the pressure of the aluminum block on the table is calculated
13. A piece of iron with a length of 0.2 m, a width of 1 decimeter and a thickness of 5 cm is placed on the horizontal ground. The density of iron is 7.8 × 103 kg / m. 3. Calculation: (1) the pressure of iron on the ground. (2) the maximum pressure of iron on the ground
14. As shown in Figure 3, with a horizontal thrust of 50 N, press the 20 N object a on the vertical wall, and the contact area between the object a and the wall is 0.01 m2. What is the pressure of the object on the wall?
15. When an alloy block with a mass of 10kg is completely immersed in water, it needs 80N force to pull it. How much buoyancy does the alloy block suffer at this time?
16. What is the buoyancy of 2.7kg aluminum when half immersed in water? What is the buoyancy when completely immersed in alcohol? (ρ aluminum = 2.7 × 103kg / m3, ρ alcohol = 0.8 × 103kg / m3)
17. When a solid stone is measured in air with a spring scale, the indication is 10N. When the stone is completely immersed in water, the indication measured by the spring scale is 6N
18. A copper block is 5cm long, 4cm wide and 20cm high. The density of copper is 8.9 × 103kggm3. When the copper block is hung under the spring scale and standing upright in the water, the upper surface of the copper block is 10cm below the water surface and parallel to the water surface, the following results can be obtained: (1) the gravity of water discharged by the copper block; (2) the pressure of water on the upper and lower surfaces of the copper block; (3) the buoyancy of the copper block; (4) the reading of the spring scale
19. A mine with a volume of 500 decimeters and a mass of 450 kg is thrown into the water
20. What is the density of an iron block with a volume of 100 cubic centimeters and a weight of 7.6n? When it is completely immersed in water, how much buoyancy is it subjected to? At this time, if the iron block is hung on the spring scale, what is the reading of the spring scale?
[note] the methods to calculate the buoyancy of an object are as follows: (1) experimental method: F floating = G-G ', G is the gravity of the object, and G' is the reading of the spring scale of the object in the liquid. (2) calculate the object immersed in the liquid, F floating = f lower surface - f upper surface = f up - f down, which reveals the cause and essence of buoyancy. (3) using Archimedes principle, f floating = g row = ρ liquid GV row, which reveals the factors that determine the buoyancy. If an object is suspended or floating in a liquid, (4) f floating = g matter = ρ liquid GV row. Note: V matter = V row when suspended, V matter > V row when floating

How to quickly master the science knowledge of grade two, and there is no problem in the small test?
Thank you very much. It's a pity that I didn't get it-
Urgent questions

Calculation of physical density and buoyancy in grade two of junior high school
To solve the problem of density and buoyancy in junior high school physics, we have learned the pressure, density and buoyancy and Archimedes principle. We can use the balance and measuring cylinder. We have to solve the classical calculation problem and multiple-choice problem of buoyancy, density and pressure

1. Scientific and technological workers take a balloon with a volume of 330000 cubic meters into the sky, and the balloon is full of helium. If the gravity (excluding helium) of the balloon is 1 / 4 of its buoyancy at low altitude, the known density of low altitude air is 0.00129 T / m3, and the density of helium is 0.00018 T / m3, then when the balloon flies at low altitude

When the hot water in the thermos bottle is not enough, the cork is not easy to pull out after a period of time. This phenomenon shows that when the volume is fixed, the temperature of the gas is lower The pressure of the gas (assuming that the external atmospheric pressure is 1.0 × 105Pa, the cross-sectional area of the bottle mouth is 10cm2, and the force required to pull out the bottle stopper is at least 20n, the pressure of the gas in the bottle is__ Pa．

When the cork is tightly closed and the hot water in the thermos is cooled for a period of time, the temperature of the gas in the thermos will decrease, which will lead to the decrease of the air pressure in the thermos, so that the external atmospheric pressure is greater than the air pressure in the thermos. Therefore, the cork is tightly pressed on the bottle mouth by the external atmospheric pressure, and it is difficult to pull out. Atmospheric pressure f = PS = 1.0 × 105Pa × 10 × 10-4m2 = 100N

Who has the calculation of density, pressure, pressure and buoyancy

1. What is the volume of 1 m3 ice after melting into water? Does it increase or decrease? (ρ ice = 0.9 × 103 kg / m3)
2. Among the metal materials, osmium has the highest density of 22.5 g / cm3, while lithium has the lowest density of 0.534 g / cm3?
3. The weight of an empty bottle is 50g, the total weight is 1.3KG when it is filled with water and 1.05kg when it is filled with a certain liquid
4. The mass and volume of the shot put used in physical education class are measured to be 4kg and 0.57dm3 respectively. Can we judge whether the shot is made of pure lead? (the density of lead is 11.3 × 103kg / m3)
5. There is a bundle of copper wires with a cross-sectional area of 2.5 mm2 and a mass of 89 kg. The length of the bundle of copper wires can be calculated without a ruler. (ρ copper = 8.9 × 103 kg / m3)
6. A bottle can hold 1kg of water. How many kg of edible oil can be held in this bottle? (ρ edible oil = 0.9 × 103kg / m3)
7. The maximum carrying capacity of a car is 30 tons, and its volume is 40 m3. Now it needs to transport steel and wood. The density of steel is 7.9 × 103kg / m3, and the density of wood is 0.5 × 103kg / m3. How can these two materials be combined to make full use of the car?
8. A hollow aluminum ball weighs 27g. After its hollow part is filled with alcohol, the total mass is 43g. What is the volume of the ball? (ρ alcohol = 0.8 × 103kg / m3, ρ aluminum = 2.7 / 103kg / m3.)
9. The two objects are stacked as shown in the figure. The small bottom area of object a is 20 cm2, the large bottom area is 60 cm2, and the weight is 20 n. object B is a cube with a side length of 5 cm, which is placed on a horizontal plane
10. Two identical bricks, the gravity is 19.6n, the length of three edges is 20cm, 10cm, 5cm respectively. Brick a is placed horizontally, brick B is placed side by side, and the two bricks are overlapped as shown in the figure. The pressure of brick a on brick B is calculated
11. The maximum pressure that the frozen river ice can bear is 4 × 104 Pascal. The mass of a crawler tractor is 5200 kg. The total contact area between the two crawlers and the ground is 1.5 m2. Can this tractor pass through the ice?
12. The cube aluminum block with side length of 10 cm (ρ aluminum = 2.7 × 103 kg / m3) is placed on the horizontal table with side length of 50 cm, and the pressure of the aluminum block on the table is calculated
13. A piece of iron with a length of 0.2 m, a width of 1 decimeter and a thickness of 5 cm is placed on the horizontal ground. The density of iron is 7.8 × 103 kg / m. 3. Calculation: (1) the pressure of iron on the ground. (2) the maximum pressure of iron on the ground
14. As shown in Figure 3, with a horizontal thrust of 50 N, press the 20 N object a on the vertical wall, and the contact area between the object a and the wall is 0.01 m2. What is the pressure of the object on the wall?
15. When an alloy block with a mass of 10kg is completely immersed in water, it needs 80N force to pull it. How much buoyancy does the alloy block suffer at this time?
16. What is the buoyancy of 2.7kg aluminum when half immersed in water? What is the buoyancy when completely immersed in alcohol? (ρ aluminum = 2.7 × 103kg / m3, ρ alcohol = 0.8 × 103kg / m3)
17. When a solid stone is measured in air with a spring scale, the indication is 10N. When the stone is completely immersed in water, the indication measured by the spring scale is 6N
18. A copper block is 5cm long, 4cm wide and 20cm high. The density of copper is 8.9 × 103kggm3. When the copper block is hung under the spring scale and standing upright in the water, the upper surface of the copper block is 10cm below the water surface and parallel to the water surface, the following results can be obtained: (1) the gravity of water discharged by the copper block; (2) the pressure of water on the upper and lower surfaces of the copper block; (3) the buoyancy of the copper block; (4) the reading of the spring scale
19. A mine with a volume of 500 decimeters and a mass of 450 kg is thrown into the water
[note] the methods to calculate the buoyancy of an object are as follows: (1) experimental method: F floating = G-G ', G is the gravity of the object, and G' is the reading of the spring scale of the object in the liquid. (2) calculate the object immersed in the liquid, F floating = f lower surface - f upper surface = f up - f down, which reveals the cause and essence of buoyancy. (3) using Archimedes principle, f floating = g row = ρ liquid GV row, which reveals the factors that determine the buoyancy. If an object is suspended or floating in a liquid, (4) f floating = g matter = ρ liquid GV row. Note: V matter = V row when suspended, V matter > V row when floating

Second grade physics buoyancy pressure calculation problem,
There is a circular water tank with a bottom area of 300CM3. Now, a 790g iron block is put on a 1220g wood block, and all the wood blocks are just submerged in the water. If the iron block is taken down and put into the water, how much is the pressure change of water on the bottom of the water tank? (P iron = 7.9 * 103kg / m3)

At the beginning, the total weight of wood and iron is equal to buoyancy: G total = ρ water GV total 0.79 * 10 + 1.22 * 10 = 1000 * 10 * V total V total = 2010cm3. After taking down the iron and putting it into the water, V iron = m iron / ρ iron = 790 / 7.9 = 100cm3. At the same time, the buoyancy is equal to gravity: G wood = ρ water GV row 1.22 * 10 =

At room temperature, a steel ball can just pass through a round sleeve. After heating the steel ball, the steel ball cannot pass through the round sleeve
A. The mass of steel ball becomes larger B. the density of steel ball becomes larger C. the volume of steel ball becomes smaller D. the density of steel ball becomes smaller

At room temperature, a steel ball can just pass through a circular sleeve. After heating the steel ball, the steel ball expands and its volume increases. Therefore, the steel ball cannot pass through the circular sleeve, but its mass does not change with the change of its temperature. According to the density knowledge ρ = MV, when the mass remains unchanged, the volume of the object increases, and the density of the object decreases

Calculation of buoyancy pressure in the second year of junior high school 20 calculation problems about buoyancy pressure I will add 20 points after answering