I m in a hurry, a basic physics concept, and I don t understand it, but the good Samaritan can help

1.When the coin starts rolling, the lowest point can be A and the highest point can be B.

When rolling, A and B both do two movements, one is to translate with the center of the circle, and the other is to rotate around the center of the circle. After half a lap, A moves horizontally for half a circle while running to the highest point. It's the same for B, move horizontally for half a week while running to the bottom.

Trajectories are all curves. That is, the magnitude of the displacement of A and B is the same, and the distance of A and B is also the same.

But the displacement of a and the distance of a are not the same.

Therefore, the displacement of each point on the circumference of the coin and the magnitude of the distance are the same.

Note: The emphasis is on "every dot" on the circumference of --- coin!!

10 revolutions is an integer! , 10 Weekends!! - Displacement = 10 circumferences, isn't the size equal to the distance???

Note: If it is not an integer number. Don't wait--- specific problems are analyzed? The particle says that the displacement of unidirectional linear motion is the same as the distance ---but it is not denied that other cases cannot be equal)

The displacement and distance of the center of the circle (centroid) are 10 times the circumference.

The second question itself has some ambiguity that leads to problems in understanding:

If you want to compare the distance of each point (except the center of the circle) with the displacement of each point, obviously your teacher is mistaken, first of all, the displacement of no point is 10 times the circumference, but the distance must be greater than 10 times the circumference. You can draw a point of the trajectory line to look at it, it is an arc.

If it is said that the comparison is the distance and distance comparison of each point, the comparison of the sweatshirt and the displacement, it is obviously equal.

By the rated torque of the speed t, t=9549*p n, t unit loss is newton per meter, p unit is kilowatt, n unit is revolution per minute, by the angular velocity of frequency f pin pin pin w, w = 1 f, the mechanical power of the engine is p1 = tw, the joule power of the engine is p2 = ui, so its total power is p3 = p1 + p2, assuming that its working time a day is t, then it consumes energy a day w = p3 * t, check the tool table to get the calorific value q you use, Then the oil used for a day is assumed to be m kilograms, and the heat generated should be q=m*q, and you can get the m you want from q=w

This attraction exists between any two objects. This attraction between objects is prevalent between all things in the universe and is called gravitational force.

The acceleration of an object is directly proportional to the resultant external force f experienced by the object, inversely proportional to the mass of the object, and the direction of acceleration is the same as the direction of the applied force.

Power refers to the work done by an object in a unit of time, i.e., power is a physical quantity that indicates how fast or slow the work is done.

Because v=dx dt

So dt=dx v

Substitute a=dv dt to get a=dv (dx v)=v (dv dx) I hope mine is helpful to you, hope, thank you!

The absence of physical structures means that they are not composite structures but a whole. Perhaps one will find a mathematical structure that, in some way, is generally a kind of "straight sum" () that can be broken down into several subsystems

Substituting dx=VDT into the latter form gives the former formula.

"potential" means one according to my understanding"level"or"Capabilities"。"Equipotential"It is equivalent to having the same level of class. An equipotential surface is a surface composed of all points at the same level, and such points should all be in the same position, and the surface formed by such points will be perpendicular to the electric field line.

For example, if all the people of the same height stand together, the top of their heads can form a surface, and this surface is not perpendicular to the direction in which everyone is standing, parallel to the ground, right, the direction of each person's height is equivalent to the direction of the electric field line. And the surface overhead is equivalent to an equipotential surface.

Then there is the direction of field strength, and all values with the word "strong" in physics should be ratios. That is, the value on the "unit". And the tangent has the meaning of a unit. So I personally think that the tangential direction is more rigorous.

For the exam, it is better to follow what is said in the textbook.

The potential at a point is the number of power lines passing through the unit cross-section of that point, so that it can be understood that the electric potential near the cross-section perpendicular to the power line is equal. Of course, strict explanations should be quantified.

The electric field lines and the field strength are in the same direction, no"The tangent direction of the electric field lines is the direction of the field strength"Such a statement.

This depends on the nature of the power supply. There are constant current power supply, constant voltage power supply. It literally means that an output current is fixed and an output voltage is fixed.

Assuming that it is a constant current, only 2 bulbs are connected in parallel and one bulb is removed, then there is one less circuit to divide the current, and the other current will definitely become larger. If the resistance does not change, the voltage increases.

If this one is short-circuited, and you don't think about things like the power supply burning, the current of the other bulb will become zero, because the circuit has been short-circuited and no current is going through. The voltage is basically equal to 0Burning the filament is the same as removing the bulb.

If two bulbs are connected in series, if one is removed, the circuit will be disconnected, and the current and voltage will be equal to 0In the case of a short circuit, the current does not change because it is only one circuit and it is constant current. The voltage at both ends of the remaining bulbs also does not change.

In the case of a constant voltage power supply, if one bulb is removed in parallel, the voltage of the other bulb will not change, so the current will not change.

If there is a short circuit, the current and voltage are basically equal to 0

When connecting in series, remove one ditto, the circuit is disconnected, and the current and voltage are equal to 0If a bulb is short-circuited, the voltage will become larger, because the voltage is constant and there is one less bulb to divide the voltage. The resistance does not change, so the current will also increase.

Answer: Assuming that there is no internal resistance in the external circuit, remove one small bulb and the current of the other one remains unchanged. Because the voltage applied to the bulb does not change.

However, in reality, there is always internal resistance in external circuits. By removing a light bulb, the resistance of the external circuit increases. (The total resistance of the bulb in parallel is definitely less than that of one bulb) so the partial voltage of the bulb also becomes larger, so the bulb becomes brighter.

If there is a short circuit, the other bulb will go off because there is no partial pressure on it. If it is a series circuit, remove a light bulb, and the circuit will be broken, and the light bulb will not be able to light up. If there is a short circuit, the other bulb will brighten up because its partial pressure increases.

Previously it was the voltage of two bulbs and for the external voltage, now it is the voltage of one bulb for the external voltage, so one bulb will brighten.

It should be a resonance phenomenon.

The frequency of the breeze happens to be close to the natural frequency of the lake, while the frequency of the strong wind is too far apart.

You must know that theoretical things are irrational in many practical applications, you are observing a natural phenomenon, and natural things must be explained from a natural point of view, not purely by theoretical knowledge. What is the difference between not being able to leave a textbook empty without connecting it with reality, and talking about it on paper? Back to the question, is the lake you are looking at an absolute experimental model?

Isn't there a bump at the bottom of the lake? Are there no creatures in the lake? Isn't there a methane-like gas produced at the bottom of the lake?

There are also many natural causes, such as whether there are ships on the lake, whether people are using the lake resources, and so on. Many external factors can cause your theory to fail.

I think it has something to do with the model, the laboratory model is a water basin, the surrounding area is bounded, but the interface of the lake is an inclined plane, in terms of the movement of water, the interface of the lake is a ...... of changeAs for the wave theory, I don't really understand it, but let's just talk about my personal feelings.

The simplest application of the principle of the communicator is a kettle for boiling water.

Because the communicator is filled with the same liquid, and the density of the left and right liquid columns is the same, according to the formula of liquid pressure P= Gh, it can be seen that the pressure of the liquid columns on both sides can be equal only when the height of the liquid columns on both sides is equal. Therefore, in the case that the liquid does not flow, the liquid level in each container of the communicator should be kept flat.

It's entirely possible.

The case of 1 can be imagined as two separate U-shaped communicators, each filled with liquid, and the liquid column height in the diagram is maintained after equilibrium. Then connect the two communicators, and this is the case in Figure 1.

Will the liquid columns on both sides change after connection, apparently not.

So the situation of 1 is entirely possible.

Figure (1) Possibly, the gas pressure in the middle is equal to the atmospheric pressure outside. Using the principle of a communicator, two communicators are actually combined.