Two questions about buoyancy. A question about buoyancy.

1.Imagine a cube with a regular shape, submerged in water, its 6 faces are subject to the pressure of water, because its left and right sides, the front and rear sides of the surface under the water depth is the same, then the pressure of the water is also the same, the pressure is equal in size, the direction is opposite, balanced with each other, and the upper and lower sides are in different depths in the water, the pressure of the water is small, the pressure is also different, the lower surface is subjected to the upward pressure of the water f is greater than the upper surface by the pressure of the water f downward. The net force of the pressure on the object is the buoyant force of the liquid on the object.

2.Analysis: The key to answering such questions is to determine the relationship between the volume of water discharged by the iron block before melting and the size of the iron row after the ice cube is melted.

Solution: Because: Ice cubes float on the water.

So: floon g ice.

And because of Archimedes' principle, it can be known.

G row f float.

m does not change when the state of matter changes, which can be seen.

Gigium gigrateization.

So: g row f float = g ice gig.

According to the Archimedes' formula.

Water v drain g g = water v g g

Therefore, V row V.

If the iron floats on the surface of the water together with the ice and sinks to the bottom after melting, the buoyancy decreases, and the volume of the water discharged decreases, so the water surface drops.

1.According to the definition of buoyancy;

2.Considering separately, the water produced by the melting of ice is just equal to the volume of water that needs to be discharged from the floating ice, so the melting of the ice will not cause the water surface to rise, and because the mass of iron is twice that of water, the volume of water that needs to be discharged by the floating iron is twice the volume of the iron, and the water that can only be discharged by 1 times the volume of the iron after the iron sinks, so the sinking of the iron will cause the water surface to fall. That is, the water level drops after the ice melts.

1 Buoyancy is the force of water on an object, where water only has upward and downward pressure on the object, so the subtraction of the two forces is buoyancy (it doesn't matter if the force is a vector quantity, you will know it after high school).

2 I've already been very specific upstairs, so I'll summarize it.

If the density of the objects in the ice cube is less than that of the ice, then the water surface rises.

If the density of objects in the ice cube is greater than that of ice, then the water surface will fall.

If the density of the object in the ice cube is equal to the ice, then the water surface does not change.

It can be compared with the next question.

Two objects are thrown into the same liquid, A floats and B is suspended. Knowing that the volume of object A is greater than the volume of object B, and the volume of object A in the lower part of the liquid surface is equal to the volume of object B entering the liquid, then what is the comparison of the gravitational force of the two objects?

ga>gb ga2.Two identical beakers with the same quality of water, respectively on the left and right ends of the balance, when a small ball is hung with a thin rope and immersed in the left cup, and the ball does not touch the cup, which end of the balance falls? or balance.

When floating and levitating, buoyancy is equal to gravity.

2.The left end sinks. When an object is immersed in water, it experiences an upward buoyant force, which, according to Newton's third law, gives the water a downward force, causing the left side of the balance to become more forceful, and then sinks.

1 is based on the balance of two forces. At that time, the state of motion of the object remains stationary.

2. Decline, calculated according to the average density.

1 is based on the balance of two forces. At that time, the state of motion of the object remains stationary.

2. I don't know.

Of course, without the gravity of water, the "bucket" can be of any shape: spherical, cubic, cylindrical, 、......

Teaches you a quick algorithm that is useful when filling in the blanks.

According to the given conditions, the density of the bucket is times that of water, and the gravity of the water it distributes is 1 of its own gravity, that is, the buoyancy is 2 5 of its own weight, so.

Buoyancy 1 10 2 5 4n

Pull force 1 10 3 5 6n

Because the bucket is completely immersed in water, the buoyancy of the water on the bucket is subtracted from the gravity of the water instead of the water ((according to: the bucket weighs 1 kg, and the density of the material of the bucket is 2500 kg per cubic meter. After calculating the volume, find the buoyancy of the water).

A bucket can hold 15 kg of water (the bucket is trapezoidal)" this condition is redundant.

Give you ideas, and the process is up to you. If you don't understand, ask again!

Principle: Because buoyancy = volume immersed in water i.e. the actual volume of the barrel, not the volume (15 liters of 15 kg of water).

So, buoyancy = barrel weight Material density f=mg = 1*hand pull force = barrel weight - buoyancy experienced by the barrel f=mg-f=1*g=

When the boat floats on the water, gravity and buoyancy are equal in magnitude and opposite directions, and they are a pair of balancing forces.

Boats