Interesting science knowledge of physics. Physics class is undoubtedly boring. When we give our children physics lessons again, we can talk about some interesting physics knowledge to arouse their interest in physics knowledge. Next, I will show you more interesting knowledge about physical science.

Interesting science knowledge of physics 1

1. The planetary density of the solar system is the earth where we live. The average density of the earth is about 5 or 5 grams per cubic centimeter, and the density of the core is the highest. The earth is really the most unique! )

2. The universe is a skilled blacksmith. In a cosmic vacuum, when two metals of the same type come into contact, they will automatically fuse together. This wonderful phenomenon is called "cold welding" by scientists! (Natural black technology, but it's really cold in outer space)

3. In fact, nuclear reactor is not a patent of human beings. As early as 2 billion years ago (you read it correctly), there were nuclear reactors in operation: the discovery of Oklo nuclear reactor and this reactor alarmed people at that time, and the whole world was discussing whether it was the product of alien civilization, but in the end scientists proved that it was a pure natural nuclear reactor, which had been reacting for hundreds of thousands of years. )

4. Will the north and south poles of the earth be reversed? Some scientists have pointed out that in the past 70 million years, the north-south magnetic field of the earth has reversed hundreds of times, and the speed of switching is accelerating, but no one in this world can explain the reason for the reversal of the earth's magnetic pole (the earth is a heartbreaking place, one moment here, the other moment there).

5. The temperature of the earth can reach 100 degrees Celsius. According to records, the temperature in Libya, the hottest region in the world, can reach 58 degrees Celsius, and the coldest records are -89 and 2 degrees Celsius measured at 1983 Antarctic scientific research station. You wear short sleeves in the sunny days in the south, and I slide freely in the ice and snow world in the north! )

If you can live on the ancient earth, you can see that the color of the earth is probably purple. Scientists have a hypothesis. Different from using chlorophyll to absorb sunlight now, plants on ancient earth rely on photosensitive optic nerve cells, which make plants look purple (purple stands for maturity).

7. As the saying goes, many hands make light, so does hair. One braided hair can bear the weight of two elephants, and even one hair can easily lift an apple, as long as there is nothing wrong with your hair (brag to friends, there is a new draft behind).

8. From the whole historical process of mankind, the number of human beings who once lived or are living on the earth is as high as 654.38+02 billion, including you now (the world is bustling, the world is bustling, and life and death are instantaneous).

9. Not all creatures in the world have red blood, but octopus's blood is blue. Why didn't I notice when I was eating grilled octopus? )

Interesting knowledge of popular science in physics II. Causes of earthquakes

The earthquake, the earth moved. Earthquake is a kind of natural disaster that has great influence on human society and even nature. So, how did the earthquake happen?

Folklore: Ancient science was underdeveloped, and people often relied on the power of God to explain natural phenomena. There is a folk saying in our country that there is a crocodile under the earth, and it will shake when you blink your eyes.

In ancient Greek mythology, Poseidon was the god in charge of earthquakes.

Of course, these are all nonsense and absurd. With the progress of science, people no longer believe this statement, so what is the cause of the earthquake?

According to the different causes of earthquakes, earthquakes can be divided into five types:

Tectonic earthquake: The reason of tectonic earthquake is that the underground strata are subjected to geostress. When the local stress is so great that the rock stratum can't bear it, it will suddenly break or dislocation quickly. When the rock stratum is broken or dislocated, it will stimulate seismic waves that spread around, and when local seismic waves reach the surface, it will cause ground vibration. 85%-90% of earthquakes in the world and all earthquakes that cause major disasters belong to tectonic earthquakes.

Volcanic earthquake: An earthquake caused by volcanic eruption.

Reservoir earthquake: an earthquake occurred in the reservoir area due to water storage and discharge.

Collapse earthquake: an earthquake caused by stratum collapse.

Artificial earthquake: an earthquake caused by human activities such as nuclear explosion and artillery fire.

Plants can predict earthquakes.

Before a big earthquake, many animals often have abnormal reactions and make predictions about the earthquake. So, can plants predict?

When investigating the changes of plants before the earthquake, seismologists in China found many noteworthy situations. For example, before the earthquake, dandelions bloomed in advance in early winter; Sweet potato vines will suddenly bloom abnormally; Bamboo suddenly bloomed and died in a large area. These anomalies usually indicate that an earthquake is about to happen.

Albizia Albizia can react two days before the earthquake, feel the earthquake and have unusually large current; During the aftershock, the current activity gradually weakened accordingly.

frosting

Frost is white ice crystals formed by water condensation on the ground or objects. It is a natural phenomenon that often occurs in cold weather, so how is it formed?

In the early morning of cold season, grass leaves and clods are often covered with a layer of frost crystals. They shine in the rising sun and melt when the sun rises. People usually call this phenomenon "frosting". Looking through the calendar, every year from 10, there is always the solar term "first frost". We have seen snow and rain, but no one has seen frost.

In fact, frost does not fall from the sky, but is formed in the air near the ground.

Frost is a kind of white ice crystal, which mostly forms at night. In a few cases, it can also begin to form before sunset when the sun is tilted. Usually, the frost will melt soon after sunrise. But when the weather is cold or in a cool place, the frost will last all day.

The formation of frost is not only related to the weather conditions at that time, but also related to the nature of attached objects. When the surface temperature of the object is very low, but the air temperature near the surface of the object is relatively high, there is a temperature difference between the air and the surface of the object. If the temperature difference between the surface of an object and the air is mainly caused by the radiation cooling of the surface of the object, when the warmer air contacts the surface of the object, the air will be cooled, and when the water vapor is supersaturated, the excess water vapor will be precipitated. If the temperature is lower than 0℃, the excess water vapor condenses into ice crystals on the surface of the object, which is frost. Therefore, frost is always formed under weather conditions that are conducive to radiation cooling on the surface of objects.

Why are there different colors in the sky?

Nature is colorful, and it is easier for us to understand the color of the solid we touch, but why do the colors of the flowing clouds and the unpredictable sky show so many changes?

Different colors in the sky are caused by the scattering of sunlight in the atmosphere under different meteorological conditions. The color of the sky we see is actually the color of light scattered by the atmosphere. If the sky is very pure and there is no scattering effect from the atmosphere and other particles, the whole sky background will be dark except the sun, moon and stars.

The scattering effect of the atmosphere on different colors of light is not "equal opportunity". In the same heterogeneous medium, the shorter the wavelength of light, the stronger the scattering. The light intensity of blue light and violet light with shorter wavelength is 654.38+ million times higher than that of red light and orange light with longer wavelength. On the other hand, the scattering intensity is related to the size of particles in the medium. The smaller the particles, the better the scattering of short-wave light, but the worse the scattering of long-wave light.

When the weather is clear, the atmosphere is relatively pure, and atmospheric molecules are extremely fine particles, which is beneficial to the scattering of short-wave light. Therefore, blue light and purple light with short wavelength in sunlight are easily scattered through the atmosphere and scattered on the whole sky background. The sky looks blue because the human eye is not sensitive to purple light.

Why is the color of the red sea red?

Located between Asia and Africa, the Red Sea is not only clear and transparent, but also has a high water temperature, which is very suitable for swimming and bathing. Therefore, the Red Sea has always been the most beautiful seaside leisure resort in the world, attracting a large number of tourists to spend their holidays here every year. However, the most attractive thing about the Red Sea is that it often appears as red water.

The climate in the Red Sea is hot and dry, and the seawater evaporates strongly, which makes the seawater in the Red Sea have high salt content and high water temperature. These conditions are just suitable for cyanobacteria to reproduce and grow here. In fact, blue-green algae is not blue-green, but red. A large number of red algae appear in seawater, and the seawater naturally reflects red.

Secondly, red sandstorms from sub-Saharan Africa often attack the Red Sea. When strong winds rolled up waves of red dust and scattered it over the Red Sea, the sky was dyed red. Coupled with the red waves, the sky, the sea water and the red rock wall along the coast, everything is reflected red, thus forming a beautiful and peculiar landscape of the Red Sea.