1. The edge length of cube abcd-a'b'c'd 'is 1. If e is the midpoint of DD', then the distance from B 'to plane Abe is \. 2. In the xoy rectangular coordinate system, it is known that a (4,0), B (0,4), the light ray emitted from point P (2,0) is reflected by the straight line AB, then it is reflected by the straight line ob, and then it is returned to point P, then the path of the light ray is \. 3. Let a, B and C be unit vectors, and a · B = 0, then the minimum value of (A-C) · (B-C) is uuuuuuuuuuuuuuuuuuuuuuuuuu. 4. If the function f (x) defined on R belongs to R for any X1 and X2, f (x1 + x2) = f (x1) + F (x2) - 1 holds, and if x > 0, f (x) > 1. 1) It is proved that f (x) - 1 is an odd function; 2) It is proved that f (x) is an increasing function on R; 3) If f (4) = 5, solve the inequality f (3m ^ 2-m-2)

1. The edge length of cube abcd-a'b'c'd 'is 1. If e is the midpoint of DD', then the distance from B 'to plane Abe is \. 2. In the xoy rectangular coordinate system, it is known that a (4,0), B (0,4), the light ray emitted from point P (2,0) is reflected by the straight line AB, then it is reflected by the straight line ob, and then it is returned to point P, then the path of the light ray is \. 3. Let a, B and C be unit vectors, and a · B = 0, then the minimum value of (A-C) · (B-C) is uuuuuuuuuuuuuuuuuuuuuuuuuu. 4. If the function f (x) defined on R belongs to R for any X1 and X2, f (x1 + x2) = f (x1) + F (x2) - 1 holds, and if x > 0, f (x) > 1. 1) It is proved that f (x) - 1 is an odd function; 2) It is proved that f (x) is an increasing function on R; 3) If f (4) = 5, solve the inequality f (3m ^ 2-m-2)

1. When f (x) - 1 is an odd function, f (- x) - 1 = - f (x) + 1, that is, f (x) + F (- x) = 2, we prove that if f (x) - 1 is an odd function, f (- x) - 1 = - f (x) + 1, that is, f (x) + F (- x) = 2

There are n red balls n ≥ 5 and 5 white balls in one pocket. If you touch two balls in one touch and the two balls are different in color, you will win the prize. Record three touch and put them back after each touch. The probability of winning the prize once is p. when n is taken, P is the largest?

The reason is as follows: because it is put back every time, three times of prize is three independent repeated experiments. Suppose the probability of winning a prize is x, then the probability of winning a prize in three times of prize is p = 3x (1-x) ^ 2 = (3 / 2) (2x (1-x) (1-x))

Choose one person from two groups to participate in an activity. It is known that there are 6 boys and 4 girls in the first group, and there are 15 people in the second group. If it is an independent event that the person selected as the first group and the person selected as the girl, how many girls are there in the second group?

The ratio of male to female in one or two groups should be the same
So we can be relatively independent, so it's 15 * 4 / 10 = 6 people

What is the scale effect clock slow effect, please tell me

Special relativistic mechanics: (Note: γ = 1 / SQR (1-u ^ 2 / C ^ 2), β = u / C, u is the velocity of inertial system.)

The () and () characteristics of animals are the standard for scientists to classify animals

Animal's (morphological characteristics) and (physiological characteristics) are the standard of animal classification

How to understand the clock slow effect and scale shrinking effect
Why does the teacher say that the ruler doesn't really get shorter

First of all, this kind of [question] should not be sent to the [philosophy] column, but to the [physics] column. Secondly, we need to have the knowledge of relativity [question]: how to understand the clock slow effect and the ruler contraction effect [answer]: This is the effect of relativity. Specifically, the effect between different reference systems

Classification and characteristics of animals
10 minutes

Protozoa are all unicellular animals, which are the most primitive animals. Among them, we are familiar with Euglena and Paramecium
There are few recorded species of endoparasites with simple structure
Sponges are primitive multicellular animals
So far, this phylum has been monopolized by one of the most powerful animals, the silkworms~
As the name suggests, ancient means that this kind of animal has been extinct, and cup means that they look like cups
There are Hydra, jellyfish, Anemone and coral in Coelenterata
7 ctenopharynophora, which has also been classified as Coelenterata, as ctenopharynophora
There are planarians, trematodes, tapeworms and other parasites that we often hear about
9. Marine zoobenthos of Urechis, having a cylindrical or long cystic body
All the glossiformes are bloodsucking parasites, and their taxonomic status is still uncertain
Strange animal is a new kind of animal discovered in 1994. Little is known about it
Any of several similar animals of the phylum annulata slightly higher than the Platyhelminthes
The phylum gnathostomata is small and lives in the fine sand of shallow sea. People don't know much about it
14. Nematoda is a large family, which contains Ascaris lumbricoides
A group of animals having cilia on the ventral surface of the body
Rotifera is small and similar to protozoa
A group of animals similar to Nematoda
There are few recorded species of marine benthos living in cold water near the poles
The phylum anostomes is similar to gill tractors
A group of animals having a snout at the front of the body of echinocephala
21. A new phylum of armored animals, discovered only in 1983, has not been accurately classified
Small mossy animals of the phylum anorectal
23. Earthworm, leech, sand silkworm of Annelida It's all in the shape of a link?
The phylum Sipunculidae is similar to Urechis
Mollusca contains a large number of common animals, which I will explain in detail later
26. The phylum Mollusca is extinct
A group of animals of the phylum Tardigrada that can endure high temperature, absolute zero, high radiation vacuum and high pressure
28 clawed animals with worm like body, cylindrical feet and claws at the end are nearly extinct
More than two-thirds of the Arthropoda fauna are species. This large family will be described below
Brachiopods sometimes you see fossils like shells on street stalls, which are the remains of these animals
The external anorectal phylum was once the same phylum as the internal anorectal phylum, which is called Bryozoa, but now it is separated from the internal anorectal phylum
There are only 10 kinds of animals in this phylum, and they are all marine benthos
The phylum Archaea was extinct in the life explosion 530 million years ago, and it was discovered only in recent years
34 echinoderms a familiar phylum, including starfish, sea urchins, sea cucumbers, and crinoids
A nonparasitic animal of the phylum acrocarpa, which has no mouth and digestive tract, lives in the deep sea and its taxonomic status is controversial
There are only about 50 species of Chaetognatha, which are marine animals
The hemichordate is worm shaped and has been classified as chordate

Could you explain the special theory of relativity briefly?

The four-dimensional space-time view of special relativity is a theory based on the four-dimensional space-time view. Therefore, to understand the content of the theory of relativity, we must first have a general understanding of the space-time view of the theory of relativity

Scientists classify animals mainly according to their () and ()

Morphological structure and living habits

A question about special relativity. Although it's very simple, I want to explain it in detail
1. In the case of velocity v = (), the momentum of the particle is equal to twice the non relativistic momentum
2. In the case of velocity v = (), the particle's kinetic energy is equal to its static energy

Suppose: the dynamic mass is m, the static mass is m, the relativistic momentum is p, the non relativistic momentum is p, the kinetic energy is EK, the static energy is E0, and the total energy is e
According to the theory of Relativity: M = m * (1-vv / CC) ^ (- 1 / 2), P = MV, P = MV, e = MCC, E0 = MCC, EK = e-e0
1) From P = 2p, MV = 2mV, m * (1-vv / CC) ^ (- 1 / 2) = 2m, 1-vv / cc = 1 / 4 v=0.866c=2.60*10^8(m/s).
2) From EK = E0, e = 2e0, MC = 2mcc, m * (1-vv / CC) ^ (- 1 / 2) = 2m, 1-vv / cc = 1 / 4 v=0.866c=2.60*10^8(m/s).