Physics Bottles, Physics Question Bottles

1.If it's in equilibrium.

Gravity = friction + pull.

2.It can be divided into: static friction, sliding friction and rolling friction.

Static friction refers to the reaction force of thrust (pull) when an object is not moving.

For example, if Xiao Ming pushes the table with a force of 100N but does not push it, the static friction on the table is 100N

2.Sliding friction refers to the translational motion of an object in the same plane, and the resistance experienced in the translational motion is the sliding friction.

For example, Xiao Ming pushes the table with a force of 100N, and the table moves in a uniform linear velocity, and the sliding friction is 100N, but if it is changed to a force of 200N, the sliding friction is still 100N (because it is not a uniform linear motion, which is very important).

3.Rolling friction refers to the resistance of an object in a circular motion on a certain surface, which is rolling friction.

It does not have a quantitative calculation in junior high school, but serves as another test center.

For example, Xiao Ming installed a reel under the table to make the table easier to push, and the physics knowledge used was that the rolling friction is much smaller than the sliding friction.

Our hand relies on the friction between the hand and the bottle to lift (hold) the bottle, the bottle itself is subjected to two forces: its own gravity and the hand to lift it, when holding the bottle, the two are balanced, so the force of lifting the bottle is equal to the gravity of the bottle.

Friction can be divided into 3 categories: sliding friction, rolling friction, and static friction.

The lifting force in the problem is static friction because the bottle is at rest relative to the hand.

There is only friction, and when translated or lifted slowly, friction is equal to gravity.

If you look at the bottle and the hand as a whole, then it's the force of gravity and the pull of the arm (strictly speaking, the wrist).

Friction classification: static friction, sliding friction, rolling friction.

As for the details, it seems that there is nothing to go into detail.

If only density is considered: sulfuric acid, mercury, salt water are fine.

However, sulfuric acid is very acidic and can only be bottled in special bottles.

Mercury is toxic and volatile, so bottles with good closure are generally considered.

Salt water is denser than water. And it is a regular thing, and it can be loaded.

I guess it's a chemistry problem. Because the chemical properties and density of the substance are taken into account.

c. Mercury is dense.

1 kg is more than enough.

CD is OK, and the density is greater than water.

Mainly the bottle vibrates.

The more water in the bottle, the more squeezed the bottle, the harder it is to vibrate, the lower the frequency, and the lower the pitch.

The opposite is true of blowing into a bottle. The more water in the bottle, the shorter the air column in the bottle, the greater the air vibration frequency, and the higher the tone.

(1) and (2) are both water and bottle vibration sounds, and the tone of less water is high. i.e. A is the highest, and D is the lowest.

3) When blowing into the bottle, the air column in the bottle vibrates and makes a sound, and the short tone of the air column is high. i.e. d is the highest, and a is the lowest.

Yes, the air in the bottle gets hot, expands and escapes some of it.

When the cap is closed, the pressure inside the bottle decreases.

Outside atmospheric pressure will be the bottle.

I think maybe the teacher misunderstood.

It's best if you ask again.

Rigorous academic attitude, o( o

Most of the inside of the bottle is hot water vapor, and after the lid is closed and cooled, it liquefies into liquid water droplets without pressure, so the bottle is deflated.

Because of the thermal expansion and contraction (air), and atmospheric pressure, it is because the air inside is hot, rising, running to the outside, after the lid is closed, it is cold, the pressure inside is smaller, the pressure outside is unchanged, the bottle is flattened, the volume is smaller, and the pressure and the outside are balanced.

No, it's the equilibrium state of the gas that has changed.

The gas follows a thermal equilibrium equation pv=nrt (p is the gas pressure v is the volume n is the amount of the gas's substance, r is the constant, and t is the gas temperature).

When the temperature drops, this equation still has to be formed, the air pressure inside and outside the bottle must be balanced, the atmospheric pressure does not change, so the gas pressure does not change, the bottle is sealed is the amount of gas substance will not change, so the volume can only be reduced.

Of course, it is heavier than air, but it is also the weight of a bottle of air, so it cannot be weighed if the accuracy is not enough. You can imagine that in the same environment as water, a bottle filled with water and a bottle vacuum, will they be the same weight?

That is to say, if the mass of the bottle is small enough in the air, the bottle in the vacuum will float, while the bottle with air will not. This is the principle of the airship, except that the airship is filled with a gas that is less dense than the air. And the gas in the airship also has mass, imagine if you can design a vacuum airship, it will have more buoyancy and carry more things.

The same heavy air has an isotropic nature, and there is pressure on the bottle downwards and upwards with equal pressure, canceling each other out, and the electronic scale cannot be sensed.

The lightness of the vacuum.

First of all, the two bottles have the same volume, that is, the air buoyancy is the same;

The second point is that air has mass, so a bottle with air is heavy.

I'm dizzy. Of course, it's the weight of the air.

Density of water: 1kg liters; Density of edible vegetable oil: lead dust to rise brother bucket.

It is obtained from Huaichang with equal volume: 1 1=x x=

It should be in the middle because it has a hindering effect on the movement of water, and in the middle it has the least effect. Since it hinders its movement in the water, it consumes much more energy to turn around on the outside than in the middle. The faster flow of water in the outer ring must also have an effect.

Just like some dancing circles, the hands are extended and closed to control the rotation speed and stop. That's what I'm thinking, please think about it!

The bottom of the bottle is round and round.

The bottom of the bottle is concave and concave.

That's going to happen. Or maybe a solid object is not much denser than water. When turning, the water moves faster than the object, and the water wants to do centrifugal motion more because the shape of the water can be easily changed, and as a result, the object is pushed towards the middle.

At first, the water in the bottle will drive the solid object to turn, and due to the vortex, the solid object will slowly turn to the center of the bottom of the bottle due to the action of gravity.

The principle is the same as that of a whirlpool.

1.I think it can be explained by the geographical "geostrophic deflection force", because the earth's rotating objects are always subject to a force perpendicular to the right in the direction of motion (northern hemisphere, southern hemisphere left), and the object in the bottle moves in a circular trajectory (clockwise), which is affected by the geostrophic deflection force, it will gradually move closer to the middle. If water is poured into the sewer, the whirlpool formed at the leak will move clockwise.

2. When rotating, the water flow speed is fast near the center, and the speed of the water flow will be a force from the slow place to the fast place (the same principle as the airplane lifts off). Make it move closer to the middle.

The second reason should be a little bigger.

Get a bottle and heat it ...Then make the egg a hole larger.

Put it on the mouth of the bottle without air leakage, and then cool the bottle.

It seems that the downstairs method is better...Let's use candles.

The glass bottle of that Coke.

incendiary gas inside the flask, and then put the egg with the hole in the mouth of the bottle, so that it cannot leak.

Use pressure.

Like a fire pot.

Put a burning candle or something in the bottle, and put an egg in the mouth of the bottle.

After the candle burns out, due to the consumption of oxygen.

The air pressure inside the bottle is reduced, and the eggs are sucked in.