Words 500-800

Words 500-800

With the development of society and the progress of science, computers are no longer unfamiliar to people. Only in the ordinary families in Beijing, the popularization rate of computers has been relatively high. For the users of computers, how to operate is no longer difficult. However, new problems have emerged. Huge information

Summer study paradise for primary school students grade 4 science P19
Here's a basin of water and two bells. Please design an experiment to show that gas, liquid and solid can transmit sound
My "gas can transmit sound" experiment:
My "liquid can transmit sound" experiment:
My "solid can transmit sound" experiment:
Elder sister, elder brother, please

Gas can spread sound: put the bell at a certain distance from the ear, shake the bell, you can hear the sound, indicating that gas can spread sound!
Liquid can spread sound: put the bell in the water, shake the bell, you can hear the sound, indicating that the liquid can spread sound!
Solid can transmit sound: put a bell in the ear, and gently hit the bell beside the ear with another bell. You can hear the sound, which indicates that solid can transmit sound

Fast production!

I'll tell you what I made at that time! No patent fee is needed: Name: environmental protection tissue tube material: a long tube biscuit box or potato chip barrel (which can be bought in supermarket), a roll of toilet paper and a pair of scissors. First, eat or pour out the food in the biscuit box or potato chip barrel, wash it, turn it into an empty barrel, and then make it empty

The size of the shadow depends on the distance between () and ()
() and () are caused by the interior of the earth, which is divided into three parts
Due to the action of () () or (), this phenomenon of rock () is called ()
Soil is a mixture of () and () and other substances
The use of light reflection is () () ()

The size of the shadow is related to the object to be illuminated and the inclination of the light to the object. If the shadow is direct, it will be small. The larger the inclination is, the larger and longer the shadow will be. Of course, it refers to the same object. The shadow of a large object is always larger than that of a small object
Volcanoes and earthquakes are caused by the movement of the earth's interior. The interior of the earth is divided into crust, mantle and core,
Due to the action of water, atmosphere, temperature, animals and plants, rocks are broken. This phenomenon is called weathering
Erosion of rock by water is called chemical weathering, heat expansion and cold contraction by sunlight or ice splitting is called physical weathering
Soil is a mixture of (water), (air), (sand), (humus), (inorganic salt), (clay) and other substances