[Source: Science and Technology Network for Middle School Students | Time: 2006-4-1613:1:50] [Font: large, medium and small]

Every Sunday, I always finish the task of shoeshine given to me by my mother. Tell you, this is the source of my pocket money for a week! After getting the leather shoes covered with dust, I first wipe off the dust on the vamp, then apply shoe polish and wipe them carefully, and the leather shoes will become bright and beautiful. But why is this?

I found two pairs of old and new leather shoes of the same brand and style for comparative observation. I first touched the uppers of two pairs of leather shoes and found that the surface of the new shoes was much smoother than the old ones. Old leather shoes are coated with shoe polish. After careful polishing, it shines a lot, but it is still not as good as new leather shoes. Is there a relationship between the brightness of leather shoes and the smoothness of uppers?

I brought a pair of old leather shoes that were not polished, and the uppers were uneven under the magnifying glass. Then, I circled two rough areas A and B on the leather shoes. Carefully wipe area A with shoe polish, and area B without shoe polish as a blank control. I found that the surface of area A is obviously smoother after wiping, and it is more shiny than area B when placed in the sun. Why is there such a big difference between them?

I remember the teacher once said in science class that the wall surface of the theater is uneven, so that most of the sounds can be absorbed and the audience will not be disturbed by the echo. Similarly, light will be reflected on the surface of any object. If the plane is uneven, light will scatter in all directions. If this plane is smooth, then we can see the reflected light in a certain direction.

The surface of leather shoes is not absolutely smooth. If it is an old leather shoe, its surface is of course more uneven and can't reflect light in a certain direction, so it looks dull. There are some small particles in shoe polish, which can just be filled into the pits on the surface of leather shoes when shining shoes. If you wipe it with a cloth again, the shoe polish will be more uniform, the surface of leather shoes will become smooth and flat, and the reflective ability will be strengthened.

Through the experiment, I finally know the secret of shoes getting brighter and brighter!

My mother once told me such a riddle: "Zhuge Liang in Nanyang, sit tight." Arrange the eight diagrams and catch the flying generals. "This myth tells us that spiders only eat living things, but don't they eat dead things? This aroused my interest and I did the experiment.

I caught a little spider from the corner and put it in a box (with holes around it and glass on it for easy observation). Before the spider could weave a web, I picked up a dead bug and a dead fly and put them in front of the spider. The spider ignored them, then hit the box with her hand, and the spider crawled in other directions.

In order to find out whether spiders eat dead flies completely, the next day, I came to the box to observe and saw that dead insects and dead flies were still in their original places, but there was a net in the corner of the box, and the spider was lying quietly on the net. At this time, I thought: Is it because there is no net that the dead flies and insects didn't eat it yesterday? So I picked up the dead fly and gently put it on the net, but the spider still didn't move. Then, I gently touched the edge of the net with my pen. Gee, the spider seems to have a reaction and started to climb in a trembling direction. I took the pen back and the net stopped shaking. The signal was interrupted and stopped. Soon, the spider climbed to the center of the web again. I touched the dead fly's body on the net with the pen tip again, and the net began to vibrate, and spiders began to crawl here. I took back the nib again and the spider stopped. Like last time, after a while, the spider climbed to the center of the web again. Oh! I finally understand that spiders feel by the vibration of their webs and prey by weaving them. So, I recorded the experimental results.

In order to prove that spiders feel through the vibration of their webs, I did another experiment. Put the pen tip on the dead fly on the net and vibrate for a long time. The vibration of the web is getting bigger and bigger, and the spider seems to feel stronger and stronger. Spiders will come in a hurry. When a spider meets a fly, I will take back the pen tip, only to see that the spider's tail will soon spit out sticky silk to tie the fly, and then look at the spider's back, as if sucking the fly. Soon, there was a complete empty shell left on the Internet. This experiment proves that spiders eat moving insects.

Our secret group went to the library and bookstore to consult a lot of books about spiders. Among them, General Zoology wrote that spiders are carnivores, and their food is mostly insects or other arthropods. But the mouth has no upper jaw, so you don't swallow solid food directly, but suck it slowly. When insects and other animals come into contact with the net, they will struggle desperately on the net to make the net silk vibrate, so that spiders will find it soon. Spiders will crawl along the longitudinal silk to their prey, wrap the prey with spider silk and fix it on the net. First, the venom secreted by poisonous glands in claws is injected into the captured prey to kill it, then the digestive enzyme secreted by midgut is injected into the captured tissue torn by claws, which is quickly decomposed into juice, then inhaled into digestive tract, and finally eaten the remaining body shell. These fully prove that flying insects make the spider's web vibrate, and the web vibration will make it feel, and the spider will catch its prey if it feels. So it is confirmed that spiders only eat live animals, not dead insects.