(1): When the loaded balloon rises vertically at a uniform speed in the air, the buoyancy is 2000N. If a 20kg object is added, the balloon can descend vertically at a uniform speed (assuming that the buoyancy and resistance of the balloon are unchanged when it rises or falls).

(1) Gravity when the balloon rises

(2) The resistance when the balloon moves.

(2): The volume of wood block is 100 cubic centimeter, and the density is 0.6x 10kg/m3.

(1) What is the buoyancy of the wood block when it is completely pressed like water by hand?

(2) After letting go, what is the buoyancy of the block at rest?

(3): When the warship is fully loaded, its weight is 7.5× 106N. What is the volume of seawater discharged when the warship is fully loaded? The density of seawater is 1.03g/cm3 (the calculation result is reserved to two decimal places).

(4): Put a piece of wood with a mass of 4kg into water, and the exposed volume of the wood after standing is 2X 10-3 m3. Find the buoyancy of wood: 1.

2 the volume of wood blocks in water

3 density of wood blocks

(5): The cylindrical container is filled with water, and a cube with a side length of 10cm floats in the water, and 1/5 of the cube is exposed out of the water;

What is the buoyancy of wood floating?

What is the density of the wood block?

(6): The thin-walled cylindrical container placed on the horizontal table top weighs 4N, and the bottom area is 100m2. A block weighing 10N is hung on the hook of the spring dynamometer. Firstly, the cube is immersed in water, and the water level in the container rises from 16cm to 20cm. Q:

(1) The pressure of water on the bottom of the container when the wood block is put into water;

(2) the density of the block;

(3) Buoyancy of the block?

(7): A piece of wood floats in the water, and 2/5 of its volume is out of the water;

1. Density of wood block;

2. If the block weighs 300g, what is the volume of the block?

(8): The wooden block floating on the water, the submerged part is 75cm3, and the part on the water is 25cm3.

Q: 1. Buoyancy of wood blocks;

2. Quality and density of wood blocks.

(9): A wooden block is immersed in an overflow cup filled with water, and 10g of water overflows from the cup. If it is completely immersed in an overflow cup filled with alcohol, how many grams of alcohol will overflow from the cup (alcohol density is 0.8× 103kg/m3, water density is 1.0× 1008).

(X): There is a piece of wood, weighing 10N. When it floats on the water, the part exposed to the water is 1/4 of its volume. Find the density of the block.

(1 1): The sum of the submarine's mass and the seawater in the cabin is 2.06× 106kg when the navy submarine dives at a constant speed on the water surface. When it dived to a depth of 300 meters, naval soldiers used compressed air to press part of the seawater out of the cabin. When 6× 104kg seawater is pressed out of the cabin, the submarine floats on the water (seawater density is 1.

1) What is the seawater pressure on the submarine at 300 meters below the sea surface?

2) What is the weight of the submarine floating on the water?

3) What is the buoyancy of submarine submerged in seawater? What is the amount of seawater discharged?