I have a question??? Physics study is good, help to solve it!!

Common ferrite magnets should be microscopically viewed as polycrystalline structures, and each single crystal in the magnet is the smallest unit of magnet. Consider magnets of the following structure ([sn] or [ns] represent the smallest magnet magnetic units of different directions):

ns][sn][ns][sn][ns]

sn][ns][sn][ns][sn]

ns][sn][ns][sn][ns]

The whole looks like left n and right s, after being broken into two parts:

ns][sn][ns]←→sn][ns]

sn][ns]←→sn][ns][sn]

ns][sn]←→ns][sn][ns]

These two parts are inevitably repulsed, and one of the two new magnets will invert the poles in terms of overall performance. The actual situation is more complicated, the minimum unit space of the magnet should be pointed in all directions, but in general, one direction is dominant.

If the "magnet" is obtained by magnetization of a soft magnetic substance, its structure:

ns][ns][ns][ns][ns]

ns][ns][ns][ns][ns]

ns][ns][ns][ns][ns]

After breaking: ns][ns][ns] ns][ns]ns][ns] ns][ns][ns].

ns][ns]←→ns][ns][ns]

The two parts are attractable, and they have just been verified with a magnetized saw blade, so you can give it a try.

Therefore, it can be said that the repulsion of the fracture after the fracture of the common ferrite magnet is caused by the special production process (powder sintering) of this magnet.

It's not the same direction as it breaks.

For example, [n s] is followed by [n s] [n s], but what if that were the case. ns

I broke it lengthwise.

n | ns | s

It will be repulsed.

The landlord doesn't understand the meaning of the expression.,What you said about the attraction of n and s in the middle is because it turned out to be a magnet when they were attracted together?

The poles of a bar magnet do not have an absolute ns

It is easy to understand from Ampere's theory of microscopic electromagnetism.

The pole change is not that simple.

The phenomenon you said exists in Ye County, but it must not be a bar magnet, it is likely to be a ring magnet, and after it is broken, the polarity of both sides of them is the same, and they naturally repel each other.

1. Whether the internal resistance of the motor is the total resistance depends on whether there is other resistance in the resistance, if there is no other resistance in the whole circuit, the inner group of the motor is the total section group of the entire circuit. Because it contains a motor, it is a non-pure resistive circuit, so the U=IR of the entire circuit is not true.

2. The voltage at both ends of the motor U=IR (R is the resistance of the motor), this formula is no longer valid. In other words, this formula cannot be used to calculate the voltage at both ends of the motor. Circuits in which motors are present are non-purely resistive circuits.

As long as you select an electric motor in the object of analysis, U=IR does not hold.

3. For pure resistance other than the motor, U=IR is still valid.

For electric motors, by the law of conservation of energy, the electrical power of the motor = thermal power + mechanical power, that is, UI = i square r + p mechanical power.

The voltage relationship and current relationship of the series-parallel circuits in the circuit still holds.

4. Happy New Year to you, too.

An electric motor is a non-pure resistance machine, and part of the electrical energy consumed is converted into the mechanical energy of the blade rotation, and part of it is converted into thermal energy on the internal resistance. The voltage at both ends of the motor cannot be obtained by multiplying the current by the internal resistance, but it can be obtained by dividing the total power by the current. The heat of impure resistance is mainly the heat energy consumed by converting into internal resistance, which can be calculated by multiplying the square of the current by the inner resistance and the time.

1) As the title knows, v aluminum = v copper.

m copper p copper = cubic decimeter.

So the quality of the aluminum parts:

M Aluminum = V Aluminum P Aluminum = Kilograms.

2) When the water freezes, the mass remains the same.

M ice = M water = P water V water = 1 * 10 3 * 5 = 5 * 10 3 kg.

So, the volume of ice that freezes;

vu ice = m p ice = 5*10 3 cubic meters.

3) Volume of 900 grams of iron:

v=m/p=900/<120cm^3.

So it's a hollow ball.

hollow volume; V-ball -v=

4) The volume of ice:

v=m/p=

The mass of 2dm 3 ice:

m=pv'= kilograms.

When ice melts into water, the mass does not change.

So the mass of melted water is kilograms.

5) When 540 grams of water is placed in a 450 bottle, the total mass should be:

m total = 540 + 450 = 990 grams.

But it's only 790 grams. Description: 990-790 = 200 grams of water spilled from a full bottle of water.

200 g volume of water;

v overflow = m overflow p = 200 1 = 200cm 3

Because the object is submerged in water.

Middle. So, v object = v overflow = 200cm 3

Density of the object:

P = m v = 540 200 = g cubic centimeter = kilogram cubic meter.

Analysis: To take into account the problem of echo, so in seconds, the distance of sound propagation is twice the depth of the wellhead, so finally divide by 2

Answer: The depth is 340 meters.

The distance that the sound passes is twice as deep as the well! You can ask for it yourself!

Divide by 2 equals, multiply by 340ms equals 255m + min thanks.

1. The calorific value of alcohol is [.

2. When the car brakes on the highway, the wheels stop rotating, and the surface temperature of the tire will rise sharply to produce smoke and leave black marks on the ground.

3. How many kilograms of alcohol do you need to burn to get the heat to the eighth power?

m=qput q=(。

4. Tell how energy is transformed in the following phenomena.

1) Generator power generation [mechanical energy is converted into electrical energy].

2) Gas expansion does work [internal energy is converted into mechanical energy].

3) Firecrackers take off in the air [chemical energy is converted into internal energy and then converted into mechanical energy].

5. Judgment of true or false: when the object does work externally, its own energy must be reduced. Correct

6. The following statement is correct [a].

a. The temperature of the metal remains unchanged during the melting and solidification of the liquid metal.

b. After the object absorbs heat, the temperature must rise.

c. The boiling point of water in any case is 100 degrees Celsius.

d. The temperature of the ice must be lower than 0 degrees Celsius under any circumstances.

7. The temperature of the object increases, indicating [d].

a. Its internal energy increases, and the heat does not change b. The speed of molecular movement does not change, and the heat increases.

c. The speed of molecular motion remains unchanged, and the internal energy increases d. The speed of molecular motion accelerates, and the internal energy increases.

Answer: When the cap is suddenly opened, the gas in the bottle expands rapidly, and the internal energy is [reduced], the temperature is reduced, and the water vapor near the bottle mouth is cold [liquefied] to form a large number of small water droplets, which is the "white gas" we see.

9. When rinsing Xiaohong**, you need 200 grams of warm water at 40 degrees Celsius. At that time, there were only two kinds of water at 10 degrees Celsius and 90 degrees Celsius at home, so how many grams of each was needed to mix into the water needed? (excluding heat loss).

Solution: Q=cm t represents cold water heat absorption and hot water heat release respectively

Q aspiration = cm1 (40 -10).

q amp = cm2 (90 -40).

Column equations: m1+m2=200g; cm1(40℃-10℃)=cm2(90℃-40℃）。

Solving this system of equations yields: m1 = 125g m2 = 75g

These questions are worth some points, please!

1.This is to find on the Internet, preferably an encyclopedia.

2.Mechanical energy to internal energy.

3.There are values in the textbook, but I don't know.

4.(1) Generator power generation (chemical energy to electrical energy).

2) Gas expansion does work (internal energy is converted into mechanical energy when heat is transferred, and human chemical energy is converted into mechanical energy when work is done).

3) Firecrackers rise in the air (chemical energy is converted into mechanical energy, as well as internal energy) 5False, only if no energy is input.

8.Work is done to reduce condensation.

9.I don't know the exact number for this to be calculated.

1- Check it online, I don't remember either;

2. Mechanical energy is converted into internal energy;

3. Divide the calories by the calories emitted by one kilogram of alcohol;

4. (1) Other energy (such as hydroelectric power is the mechanical energy of water) is converted into electrical energy;

2) Conversion of internal energy into mechanical energy; (The same as the internal combustion engine works).

3) chemical energy is converted into internal energy and then into mechanical energy;

5 to 6, A to , metal is a crystal with a melting point and a boiling point.

bFalse, e.g. water absorbs heat when boiling, but the temperature remains unchanged at 100 degrees Celsius under standard conditions;

c False, it is related to atmospheric pressure, low air pressure and low boiling point in high mountains, and it is not easy to boil eggs;

d false, the temperature of the ice-water mixture is equal to 0 degrees Celsius.

In the 7d pair, temperature is a sign of the average speed of the molecular motion of an object, and the temperature increases, the molecular motion accelerates, and the internal energy increases.

8. Answer: When the cap is opened suddenly, the gas in the bottle expands rapidly, the external (work), the internal energy (decreases), the temperature (decreases), and the water vapor near the bottle mouth is cooled (liquefied) to form a large number of small water droplets, which is the "white gas" we see.

9. Set 10 degrees Celsius water to x grams of 90 degrees Celsius water y grams x + y = 200 ......（1）

Because water at 90 degrees Celsius drops to 40 degrees Celsius to release heat, let the specific heat capacity of the water be c, and the heat released is: (90-40)*x

Because water at 10 degrees Celsius rises to 40 degrees Celsius to absorb heat, let the specific heat capacity of the water be c, and the heat absorption is: (40-10)*y

Hot water transfers heat to cold water, which is conserved by energy: heat released = heat absorbed.

50x=30y（2）

The equation can be solved by the two equations (1) and (2).

Yes. If you don't envy the old, you can compare it with this acre. The centripetal force experienced by an object A on the ground = mv 2 r, while the centripetal force of a geostationary satellite in orbit = gmm (r+h) 2

Draw you a schematic diagram of the structure of a multi-meter, and if you look at the battery installation method inside, you will understand the question you are asking.

In fact, the positive pole of the battery inside the multimeter wants to be connected with the black watch pen, the black watch pen has a high potential, and the negative pole of the battery is connected with the red watch pen, and the red watch pen has a low potential. Therefore, when measuring the unknown resistance, the multimeter is equivalent to a power supply, and the current flows from the black meter pen into the resistance. Resistors flow out of the red pen.

Hope it helps.

Because when measuring the resistance, the positive pole of the battery in the meter is connected to the black watch pen, so the black watch pen is the positive pole and the electric potential is high.

However, this is not the case with the numeric table that is now widely used, with the red watch pen being the positive pole.

The ohmic file of the multi-meter has an internal power supply, and the positive pole is connected to the black watch pen. Remember: the current of a multimeter is always red in and black out.

When measuring resistors for many purposes, the black watch pen is connected to the + stage of the internal power supply, so it is a high potential.

The current flow direction is still from the black pen to the multimeter, from the red pen to the multimeter, and from the black pen to the resistance.

Let's make an assumption: your point of view is correct.

Then, the two balls will continue to attract each other because of the difference in their charges, and will not separate. So, according to the same reason, the two of them will continue to exchange charges, and the grass ball will be positively charged, and the charged object will be negatively charged; So I continued to ......In fact, this is certainly not possible. If this is possible, it does not comply with the law of conservation of energy.

This is not a proof question, just memorization. That is, they will have the same kind of charge.

You can also analyze and understand the reason from the perspective of the electric field. What effect will the presence of an electric field have on the charges of two objects?

I sweat, the ball and the charged object are in the same kind of charge as the charged object, so both are now negative charges, the charges are repulsive, and the repulsive force produced makes the ball be"Bounce off".

Landlord, you understand that after the neutral object comes into contact with the charged object, the charge of the original charged object completely changes is very"Non-mainstream"I hope you will pay more attention.

It is correct that the ball will suck out the charge of the charged object, but it will not absorb it completely, it can only absorb part of it, and the original charged object should still be negatively charged.

The object is negatively charged because the nucleus has a strong ability to bind electrons, so it will attract electrons that are sought by the grass, so the grass ball is positively charged.

Feel the friction is different.

1. When the left hand is gently grasped and clenched respectively, the greater the pressure, the greater the friction.

2. Replace the pencil with a ballpoint pen with a rubber sleeve of the same thickness, hold and rotate with the same force, the greater the surface roughness, the greater the friction.