How to do the chapter on physical buoyancy!

Studying physics is all about understanding. Once you understand it, you'll know what conditions to look for. Buoyancy, you first have to figure out the cause of buoyancy.

Just remember the two formulas, as long as the object does not sink to the bottom and has contact with the ground, it can be considered buoyant f=g gravity.

The second is the generalization of the first, where buoyancy is equal to the volume of the part of the object submerged in the water (i.e., the volume of water expelled) multiplied by the density of the water and the gravitational constant. It is best to be determined by specific topics.

About what, is it teaching or learning, or difficult questions, additional questions, I will again.

The key is to find a good research object force analysis, there are not many formulas of buoyancy, just remember to use a set of analysis when you analyze.

It doesn't feel too difficult, but it's a lot of help to solve the problem of buoyancy in this chapter!

Can you be more specific, such as where do you need help?

Categories: Education, Science, >> Science & Technology.

Problem description: Why does a hydrogen balloon descend when it rises to a certain altitude and rises again when it descends to a certain altitude after it is released?

Analysis: Because the density of the air slows down from the bottom to the top to become smaller, it is the reason why the air is thin at high altitude.

Therefore, when the gravity of the hydrogen balloon is equal to the buoyancy position, it is in the equilibrium position, and because there is velocity when passing through the equilibrium position, it is subjected to a recovery force, decelerates, and then turns back, which can be approximated as a simple harmonic vibration. So there will be a movement of side-to-side sales up and down.

There are generally two reasons for the drop of hydrogen balloons:

First, when the hydrogen balloon rises to a certain height, the atmosphere will become very thin, and when the density of the atmosphere is less than the density of the hydrogen balloon (if the balloon is not strong enough, it will be due to the difference in air pressure**), the buoyancy of the hydrogen balloon will be less than its own gravity, and according to the inertia, it will continue to rise for a certain distance and then begin to descend (note here, we will contact the second question).

Second, the balloon is not an absolutely airtight container, and the balloon film also leaks steam, so the hydrogen will continue to leak and the balloon will fall. But this is not the main reason.

The reason why it descends and then rises is because, as we mentioned earlier, the balloon descends until it reaches a certain density in the atmosphere. At this point, inertia is still at work, and the balloon will continue to descend a certain distance before ascending.

Personally, I think it's a decline.

Because the ground gives the boat some support, and the water gives less support, so the buoyancy is less, and the volume of the water is smaller.

The level of the lake drops.

The first two explanations have some problems, and I personally think it should be an upswing.

First of all, when the ground has support for the ship, (not because the ship's gravity decreases), the buoyancy of the water on the ship decreases.

According to the formula f=pvg, so v decreases, so the lake rises.

You can continue to ask well, I wish you progress in your studies.

Decline. Because the density of the iron anchor is greater than that of water, the iron anchor sinks, so when the iron anchor is thrown, the buoyancy received by the ship and the iron anchor is less than the buoyancy of the iron anchor on the ship. The welfare becomes smaller, the buoyancy volume becomes smaller, and the water surface sinks.

If you don't take into account the change of the hull caused by the depth of the water going down the anchor, if the iron rope tied between the anchor and the boat is long enough, if the iron chain of the anchor is tied to the bottom of the ship, it rises, because there is an additional force The upward force of the anchor to the ship, no matter how small this force is! The chain floats upwards because of the buoyant force, bringing this force to the bottom of the boat and giving the boat an extra support force! So go up and ask additional questions that you don't understand or don't know what you expected.

First of all, the gravity of the boat decreases, and the buoyancy is always equal to the gravity, so the buoyancy also decreases accordingly, and according to F=PVG, the volume of the drained water decreases, and finally it rises up.

Unchanged, the surface area of the lake is large.

1。There will be no change in the liquid level.

Reason: The ice floats on the surface of the water, and the mass of the ice cube = the mass of the water discharged by the ice cube, which is equivalent to the volume of water obtained after the ice cube melts = the volume of the water discharged by the ice cube.

2. Gravity balance calculation, the mass of the wooden block = the mass of the water discharged from the wooden block, and the same is true for the iron block, and the number of words is not enough to write. Sweat.

I explain buoyancy directly, g takes 10

Buoyancy on the object = the gravitational force of the object to expel the water (which is true at all times) The mass of the object = the gravitational force of the object 10 (i.e. the mass of the object is numerically equal to one-tenth of the gravitational force of the object), and the same goes for water, the mass of water = the gravitational force of water 10

There are two scenarios below:

1. The object can float or levitate, at this time.

Buoyancy force on the object = gravity of the object discharging water = gravity of the object = mass of the object * 10 = mass of the object discharging water * 10

That is, the mass of the object = the mass of the water discharged from the object.

2. The object sinks, at this time.

Buoyancy force on the object = gravity of the water discharged by the object = mass of the water discharged by the object * 10 Gravity of the object = mass of the object * 10

1. The mass and gravity units are different and cannot be compared.

2, Ibid. 3. The gravitational force of the object's discharging water is definitely the same as the buoyant force, buoyancy = 10 * the mass of the object's discharging water (this can be obtained by the juxtaposition of the formula, which is not explained here).

4,5, you will know these after reading the above buoyancy explanation, it is clearly written.

Question 1 Not the same The volume of water discharged is the same as that of the object, multiplied by the density of water, only buoyancy and so on can be obtained.

with the gravity of draining the water.

Question 2 The same is not directly related to the mass of the object g=mg is involved???

Question 3: It shouldn't be directly related, right?

Question 4 Since it is floating, it is stationary, then the buoyancy is equal to the gravity of the object, and the gravity of the object is equal to the mass multiplied by the acceleration of gravity g???

Question 5 Gravity g=mg

1.It depends. If something like a boat. For objects that can float on the surface of the water, then m row * g = g weight. If you sink. It is not established; M row *g is less than g weight.

2.Same as 13.The quality of the drained water *g.(acceleration due to gravity) is equal to buoyancy. The premise is that the object does not sink completely. If it sinks to the bottom completely. It is not buoyancy that is experienced. It's downward pressure. The size is equal to the mass of the water discharged *g

4.The buoyant force when floating and levitating is equal to the mass of the object *g

5.The quality of the drainage*g is equal to the gravitational force of the drained water.

I'm sure you don't know very well that g = mg, g is gravity, m is mass, and g is a scale coefficient (take g = on the earth, so according to Archimedes' law (the gravity of an object discharging water is equal to the gravity of an object), m row = m matter, then g thing = m thing g = m row g.

By the way, are you in your second year of junior high school?

1 The unit of mass is kg The unit of gravity is n, and the two physical quantities cannot be equal2 The mass of the object * g = the gravitational force of the object discharging water.

3 The gravitational force of the object discharging water = buoyancy Then the mass of the discharging water * g = buoyancy = the gravitational force of the object 4 The buoyancy force when floating and levitating is equal to the gravitational force of the object Then the buoyancy force when floating and levitating = the mass of the object * g = the gravitational force of the object.

5 g=mg

If you cheat on points, I will report you mercilessly

It should be stated first that it is wrong to have equal mass and force, i.e., m row = g weight error.

1.Not necessarily equal: when the object floats in a liquid or is suspended in a liquid, g row = g weight, if the object cannot float or is suspended in a liquid, then g row 2When the object floats in a liquid or is suspended in a liquid, G row = g weight, if the object cannot float or is suspended in a liquid, then G row 3The mass of the water discharged by the object multiplied by the acceleration due to gravity is equal to the buoyant force;

4.The relationship between buoyancy and the mass of the object when floating and levitating: the mass of the object multiplied by the acceleration due to gravity is equal to the buoyant force;

5.The mass of the object discharging water multiplied by the acceleration due to gravity is equal to the gravitational force of the object discharging water.

The mass of water drained by the object is not equal to the gravitational force of the object.

1.It depends on whether the object is floating or levitating or sinking.

Just listen carefully in class.

2.in 1

1. Mass and gravity are not a unit, and it is impossible to be equal 2. If the object is floating in water or on the surface of the water, for the object, mg = g row 3, f buoyancy = mg row.

4. mg=f buoyancy.

5. Gravity and mass, g=mg.

Transform Archimedes' formula into a set of formulas.