Please enter the physics department, please enter the physics master

Dimensions: In fact, the physical dimensions are diverse, but we are familiar with three spatial dimensions and one oft-heard about temporal dimension. Dimensions in physics are mathematically defined.

The spatial dimension should only be three-dimensional. The growth of the zero-dimensional in any direction (the direction is arbitrary) forms a one-dimensional line (any line, not just a straight line), the growth of a one-dimensional line in the direction of the normal (the direction is in a plane, so it is a normal plane, and it is two-dimensional) grows to form a two-dimensional plane, and in the same way, the two-dimensional plane grows in the direction of the normal (the direction is fixed, on a straight line) to obtain a three-dimensional body. However, there is no possibility of growth in space for three-dimensional bodies, and it can be seen by inference that the zero-dimensional point has a three-dimensional growth direction, the one-dimensional line has a two-dimensional plane as the growth direction, and the two-dimensional plane has a one-dimensional line as the growth direction.

The growth direction decreases with the increase of spatial dimension. The growth dimension of a three-dimensional body is zero. Therefore, it is impossible for three-dimensional space to grow into four-dimensional space, which is called space-time, and the time dimension is a physical dimension independent of the spatial dimension.

In other words, Tomoko can only be made in three dimensions and made into two dimensions. And such a manufacturing can be science fiction. However, it is still a little more illusory.

Just as we are in a three-dimensional space, but we cannot perceive the two-dimensional space, or even prove the existence of the two-dimensional space. Because the energy of different dimensions obviously cannot be exchanged, otherwise the perpetual motion machine will really have a solid basis.

Know) three-dimensional space: the dimension in which we inhabit, constant, i.e., excluding time.

Four-dimensional space: space plus time.

Five-dimensional space: a plane of time.

This plane of time is the five-dimensional space, which is composed of an infinite number of four-dimensional spaces according to a certain axis. We can imagine that an object in five-dimensional space should span different time axes, but we can only observe a part of it on any one time axis.

The proposal of the five-dimensional space is closely related to the discovery of dark matter, and the generally accepted statement in the physics community is that the discovery of dark matter means that human knowledge ability enters the five-dimensional space, which is a qualitative change, for example, the five-dimensional space may help to obtain "antimatter" energy. How powerful is that energy?

According to scientists, the energy release of a "antimatter" energy the size of a penny coin can make 60 round trips for existing mega space operations, and it is very close to the speed of light. There is dark matter everywhere in the universe, and access to antimatter energy is "anytime, anywhere". In other words, it will be possible not only to travel between the solar system and the Milky Way, but also to travel between galaxies and between two universes through space-time tunnels (wormholes).

Feel free to enter the dimensional space. ）

The mid-latitudes should refer to three-dimensional or four-dimensional space ( b Khan, I don't know. ）

When the fan blows out the air forward, the fan is also subjected to the reaction force given by the wind, backwards. The wind gives the sail a forward force. That is to say, the car is subjected to a forward force given by the sail and a backward force given by a fan, which is equal in magnitude and opposite in the opposite direction, and the net force is zero.

The car cannot be moved.

The title says that the forward motion by the force of the sail does not take into account that the net force is zero, and the acceleration is zero according to Newton's second law. The main one is the violation of Newton's second law. And not violating the third law.

c.This design cannot make the trolley run because it violates Newton's second law. That's right!

d The sail is stressed n, and the fan is also stressed n, and this force is in the opposite direction, and the sail and fan are now part of the trolley, so of course the force is canceled out.

No, because the whole car as a whole, the fan and the sail are in the same system, the force between them belongs to the internal force of the system, the fan blows the sail forward, because the force is mutual (Newton's third law), there will also be a force of the same magnitude to push the fan back, the net force is zero, so the car can not be moved. Complete!

The conditions for sublimation and condensation of a pure substance are: the temperature and pressure of the vapor of the pure substance must be below the temperature and pressure of the three-phase point of the substance. If the vapor pressure of a solid pure substance is lower than its three-phase point pressure, the solid substance will be sublimated directly into a gaseous state when the temperature rises.

Conversely, if the pressure of a gaseous pure substance is lower than its three-phase point pressure. When the temperature is lowered below its three-phase point temperature, the gaseous substance will condense directly into a solid state.

The three-phase point refers to the intersection of the three equilibrium lines of various chemically stable pure substances in the three phases (states) of solid, liquid and gas, and when they coexist in equilibrium. The three phases have a fixed temperature and pressure when coexisting.

Helium is excluded, as helium is the only substance that does not have a three-phase point) such as water has a three-phase point temperature and pressure.

Of course, the exothermic temperature should fall, and this temperature refers to the temperature drop of the exothermic object.

1.It's just a law of physics, and I have to ask you why it melts? Why can't the state be consistent? Both sublimation and condensation are related to temperature and pressure.

2.Looking at the definition, can melting into a gaseous state be called sublimation?

3.For example, the process of solidification is not adiabatic, is it? It's going to have a heat exchange with the environment, right?

When the ambient temperature rises, the iron temperature decreases, right? Your question is to ask, what is the temperature of iron that decreases while the ambient temperature rises, and the temperature of iron decreases after heat exchange, right?

You have to study hard in junior high school.

1.Thermal low pressure, cold high pressure formed by the three-phase point of matter and thermal causes2You should use the pressurized and frozen method. Let it drop below freezing. Instead of letting it reach its melting point.

3.I don't think you may be asking why the temperature of iron drops, you should know very well about the law of conservation of energy, it should be about the temperature of the environment, right?

That's because the rate of heat release is lower than the rate at which the environment cools down to the freezing point.

I'm not from physics, I'm from composition. The acquisition and mastery of knowledge has nothing to do with the department, right? By the way, I would like to reveal that we still have == who can't compose

(1), f float = 67500 * 10 3 * 10 = (2), p pressure = p * g * h = 10 3 * 10 * (3), v velocity = s t = 300 (2 * 60) =.

You must be asking for question 17, right?

17. A: 1, 250ml is indicated on the juice box, which means that the box has a physical quantity - the volume is at least 250ml. And the volume will not be much larger than this number.

2. Because the box containing the liquid is relatively well sealed, after Li Ming sucked a part of the juice, the remaining juice blocked the straw, and the air could not enter the box, and the box was deflated. This shows that the air we live in is also pressurized, and when the pressure inside the box is less than the air pressure outside the box, the box will deflat. It's also a physical phenomenon.

1. Archimedes' law, buoyancy is the weight of discharging seawater, which is the weight of 67,500 tons of seawater.

f = g = mg = 67500*1000* n；

2, pressure = PGH; h =

3, let's not explain.

Perpendicular to the bevel.

g×cosθ

along the inclined plane g sin

g vertically up.

Perpendicular to the inclined plane, parallel to the inclined plane, perpendicular upward.

This is the second stool of the first day of the opening of the body, because of the echo of the sound.

Width=340*(

Because it is passed through first, and then reflected back. Zao Zao's so the distance is divided by 2