Middle School Physics, Lead Blocks and Balloon Movement...

Newton's first law: When an object is not affected by an external force or a balanced force (fnet=0), it always remains at rest or in a state of uniform linear motion until an external force acting on it forces it to change this state.

A balloon is only subjected to a pair of balanced forces in the vertical direction and remains in a state of rest or a uniform linear motion, so it may move in a straight line at a uniform speed or remain stationary, and is unwilling to move from motion to stationary unless it is acted upon by an external force.

Select B and move downwards. Because the balloon and lead block are completely submerged in water, as long as the volume remains the same, the buoyancy remains the same. When water is added, the overall buoyancy decreases due to the increased volume contraction due to the pressure experienced by the balloon. Gravity does not change, so it moves downward.

2.As shown in the diagram on the right, a piece of lead is hung under a small inflated balloon with a thin wire, and it is placed somewhere in the water to be at rest, and if some water is slowly poured into the pool, the lead block and the balloon ().

A can still be stationary, B moves downwards, C moves upwards.

d Stationary, upward or downward movement is possible.

Tips: This question mainly examines the floating and sinking conditions, especially requires students to have a comprehensive understanding of the suspension conditions, which is a question that deliberately breaks the routine of students' thinking. Many students think that it will always be suspended, but in fact, in this process, because of the addition of water, the liquid level increases, the pressure increases, and the small balloon shrinks, so the V row decreases, and the buoyancy decreases, and the answer is B.

If you consider the pressure, the balloon shrinks and the buoyancy becomes less b

b I'm also in the third year of junior high school [physics is not good] You see if what you said is right.

It is in the water and does not sink to the bottom, which means that it is suspended in water, and the density is similar to the density of water {according to the sinking and floating conditions} If water is added after that, the density of the water is still unchanged {density is a property} It is very sinking, and the density of the object is equal to the density of the water, so the object is still suspended. If the object is stationary, it is not suspended (it seems to be called sinking), and the same is true for the downward transportation of slag Chang grinding As for the D option, it is contradictory to a, b, and c, so...

I choose BIt doesn't seem right, if the object is stationary and doesn't sink, it's also levitating, and if you think about it, it's pure nonsense.

I thought about it again, "Pick D]] To sum up, as long as the object does not sink to the bottom, it may be levitated, even if it is moving downward

Again, exercise is relative, and again, "anything is possible" {just kidding} right! In the future, if I don't always fight, I won't leave Q.

If you do not consider the change of water depth and water density, the buoyancy and gravity are unchanged, of course, it is the stationary of the free nucleus, if you consider the water depth and density, according to the farther away from the water level, the greater the water density, that is to say, the lead block should be the same distance from the water level, and the water level rises, then the lead block also rises.

Because water is added, the liquid level increases, the pressure increases, and the small balloon shrinks, so if the V row decreases, the buoyancy decreases, and the answer is b.

Is it possible for the balloon to be completely submerged in the water at a certain point in the water? If it is completely submerged, then the slow filling has no effect on the position of the balloon, and if it is partially submerged, it will rise as the water level rises.

Choose B, because the pressure of the water increases when water is injected into the pool, while the buoyancy of the lead block and the balloon remains unchanged

The title only says "put it in the water somewhere exactly in a stationary state", somewhere, which means that the depth of the lead block and the balloon in the water when the initial state is at rest is not determined, so you should choose d.

In fact, you have said very clearly, the buoyancy is reduced, it must be sinking, the gravity is great.

1.The following statements about buoyancy are true.

c.A solid wood ball of equal mass and an iron ball are put into enough mercury and the two balls are equally buoyant when they are at rest.

2.When a solid iron ball of equal volume and a solid wood ball are stationary in water, the buoyancy experienced by f iron and f wood are represented by F iron and F wood respectively (the density of iron, the density of water, and the density of wood blocks) then (

a. Wood balls float f iron f wood.

3.When an oil tanker sails in the Yangtze River, the volume of water discharged is 300m, the buoyancy of the oil tanker is (3000 000)n, 100m of fuel oil is unloaded at the wharf, the mass of unloaded fuel is (80000)kg, and the volume of water discharged by the tanker becomes (220)m (the density of fuel oil is 0 8 10 kg m g and 10n kg).

4 Tie an aluminium block with a thin wire to the underside of a wooden block and place it somewhere in the water just at rest, and if I slowly pour some water into the water, the wooden block and the aluminium block (

b is still stationary.

5 A piece of lead is hung under a small inflated balloon with a thin wire, and it is placed somewhere in the water that happens to be at rest, and if some water is slowly poured into the pool, the lead block and the balloon (

bMoving downward--- the water becomes deeper, the pressure increases, the balloon becomes smaller, and the buoyancy becomes smaller, so it sinks.

I don't know what to ask about.

The first question must be C. A answer, the volume of the two balls is equal, the wooden ball is not completely immersed after stationing, and the iron ball is submerged, so the volume of the iron ball draining water is large, and the buoyancy is large; B answer, the two balls have equal mass, that is, the gravity is equal, after stationing, the buoyancy of the wooden ball is equal to the gravity, and the buoyancy of the iron ball is less than its own gravity; c Both balls float on mercury, and the buoyancy they receive is equal to their own gravity, and they have equal mass, so the gravitational force is equal; d The volume is equal and the mass is unequal, so the gravity and buoyancy are not equal. The second question is A.

Question 3: 3x10 6 8x10 4 220 is fine; The fourth question is the same as the fifth question, the key is to see whether it is floating, suspended or sinking to the bottom after stationary, if it sinks to the bottom or suspended, it will be static after adding water, if it is floating, it will rise after adding water, and downward movement is impossible, because it is impossible to reduce buoyancy when adding water, it can only remain unchanged or increase.

Here's the answer:

1.c (Note: Both solid wood balls and iron balls float on the surface of mercury, and the buoyancy force on both is equal to their own gravity.) ）

2.A (Description: Wooden balls float, iron balls sink to the bottom, F iron F wood).

3. （3x10^6 ）；8x10^4 ）；220) (note: calculated according to Archimedes' law and the balance of two forces).

4.b (Note: According to Archimedes' law: f = vg, it does not change, so the buoyancy is still equal to its own gravity, so it is not moving. ）

5.d (Reason: It is determined by the weight of the lead block, and it can also be said to be determined by the mass of the lead block, because g does not change.) ）

That's the standard answer!

As follows:1, c

2、a
x10^6 8x10^4 2204、a b

5. D is the first question of absolute choice C, there is no doubt about it!

Correct without taking into account the exact point of action. But I didn't see the words on the force too clearly, it should be f=300n. I hope it will be helpful to your studies, and if you can't, you can continue to ask, hopefully.

In junior high school, it is okay to draw like this.

It should be drawn in the center of the geometry.

d Motion, upward, downward movement is possible.

The buoyancy experienced by a balloon in water is related to the volume of liquid it displaces. When water is added, the pressure of the liquid increases, the balloon may shrink in size, experience less buoyancy, and may move downward. The balloon may remain stationary due to the low amount of water added, or it may move upwards due to the vibration of the water.

So stationary, upward, downward movement is possible.

Choice A is because the lead blocks hanging from the balloon are stationary because the buoyant force of the water on them is equal to the gravitational force of both.

The buoyant force experienced by an object in water is directly proportional to the height h (height from the bottom of the water) of the object in the water. Therefore, no matter how much water is added, to remain at rest due to the constant gravitational force of the object, the position of the object in the water remains the same.

Metal crystals are the attraction of atoms and electrons (in fact, it is the Coulomb force), and they are metallic bonds, and metallic bonds are not chemical bonds. This is microscopic, and the lead you are talking about is macroscopic!

Because it is pressed tightly, the middle is equivalent to a vacuum! Atmospheric pressure!

It's an explanation of the appeal.

Molecules are constantly moving in an irregular motion ...