High School Physics: Physical knowledge in life, regular exams!

High School Physics: Physical knowledge in life, regular exams!

More junior high school and high school knowledge and information, follow me, update every day ~

1. Physical knowledge in the kitchen

1. Electricity

① Rice cooker cooking rice, electric stir -fried pot, boiled vegetables, and electric kettle boil water to transform electric energy into internal energy.

② The exhaust fan (range hood) converts electrical energy into mechanical energy and uses air to transform air.

③ Three -footed plug in rice cookers, electric stir -fry, and electric kettle, insert a three -hole socket to prevent leakage and electric shock accidents.

④ The microwave oven is uniform, high heat efficiency, and no pollution. The principle of heating is to use electrical energy to be transformed into electromagnetic energy, and then transform electromagnetic energy into internal energy.

⑤ The electric lamp in the kitchen uses the thermal effect of the current to transform the electrical energy into internal energy and light energy.

⑥ The kitchen stove (honeycomb coal stove, liquefied gas stove, coal stove, firewood stove) is to convert chemical energy into internal energy, that is, fuel combustion releases heat.

2. Mechanics

① The pot of the electric kettle is connected with the pot belly, and the surface is always flat.

② The blade of the kitchen knife is thin to reduce the area and increase the pressure.

③ The blade of the kitchen knife is made of oil, so that when cutting vegetables, the contact surface is smooth and reduced.

④ The knife handle, spatula handle, and electric kettle handle have convex and concave patterns to make the contact surface rough and increase friction.

⑤ When the shovel is delivered to the coal, the coal is used to send the coal into the stove.

3. Hot science

(1) Phenomenon related to thermal expansion and heat transmission in thermalology

① Use the stove to boil water or stir -fry, so that the bottom of the pot is placed on the flames of the flames. Do not let the bottom of the pot hold the fire head, which can increase the temperature of the pot because the flame temperature of the flame is high.

② The handle of a spatula, a spoon, a colander, aluminum pot and other cooking utensils is made of wood, because the wood is a bad conductor of the heat, so that it is not hot during the cooking process.

③ The installation fan above the stove is to speed up the air convection, so that the kitchen oil fume is discharged in time to avoid pollution space.

④ The hot casserole is easily broken on the wetlands. This is because the casserole is a bad conductor of heat. When the casserole is placed on the wetland, the outer wall of the casserole is quickly inspired and contracted, and the temperature of the inner wall is reduced slowly.

⑤ When pouring the water to the thermal bottle, it is better to keep it well. Because when it is not filled, the bottle mouth has a layer of air, which is a bad conductor of heat, which can better prevent heat loss.

⑥ Sworing dishes mainly use heat conduction methods, cooking, cooking, water, etc. mainly use the convection method to pass heat.

⑦ Pour some boiling water from the thermal bottle in winter. When the tight bottle is stuffed, you often see the bottle jump immediately. This is because as the boiling water falls out and enters some cold air, after the bottle is tight, the cold air entering the cold air quickly expands, and the pressure increases, which pushes the bottle plug.

⑧ The hot soup just came out of the pot in winter, I saw that the soup noodles were not hot. It seemed that the soup was not hot, but it was hot because there was a layer of oil on the soup noodles that hinder the loss of heat in the soup (the water evaporated).

When the winter or temperature is very low, pour boiling water into the glass. You should preheat a small amount of boiling water to preheat the cup to prevent the temperature difference between the inside and outside of the glass from being too large.

After cooking, the hot eggs are soaked in cold water for a while, which is easy to peel. Because the hot eggshell and protein are cold, they will shrink, but the degree of contraction is different, which causes the two to get rid of them.

不 When grinding the kitchen knife, watering should be continuously water because the kitchen knife and stone friction work produce heat to increase the internal energy of the knife. The temperature is reduced.

(2) Phenomenon related to changes in the state of objects

① LNG uses the method of compressed volume at normal temperature to reinstate the gas liquefaction and then put it into the steel tank. When used, the pressure pressure of the liquefied gas is reduced by the decompression valve, and the liquefied gas is reduced from liquid to gaseous.

② Boil water with the iron pot of the weld. The pot is not bad. If it is not installed, put it on the fire for a while and burn it out. This is because the boiling point of the water is 100 ° C under 1 standard atmosphere, and the melting point of the tin is 232 ° C. When the water is burned, as long as the water is not dry, the temperature of the pot will not exceed 100 ° C, and it will not reach the melting point of the tin. The melting point of the iron is not good, so the pot is not bad. If the water is not burned on the fire, the temperature of the pot will reach the melting point of the tin, welded, and the pot will burn out.

③ When boiling water or cooking, the sprayed water vapor is more serious than hot water and hot soup burns. Because water vapor becomes a large amount of heat (liquefied heat) when hot water and hot soup with the same temperature.

④ Cook the food with a casserole. After the food is cooked, let the casserole leave the stove, and the food will continue to boil in the pan for a while. This is because when the casserole leaves the stove, the temperature of the bottom of the casserole is higher than 100 ° C, and the food in the pot is 100 ° C. After leaving the stove, the food in the pot can absorb heat from the bottom of the pot and continue to boil until the temperature of the bottom of the pot is reduced to 100 to 100 ℃.

⑤ Cook the food faster with a high -pressure cooker. The main reason is to increase the air pressure in the pot and increase the boiling point of the water, that is, the temperature of the cooking food is increased.

⑥ A large number of "sweating" in the water pipe wall in summer is often a sign of rain. The tap water pipe "sweat" is not the water leakage in the tube, but that most of the tap water pipes are buried underground. The temperature of the water is low. The water vapor in the air is exposed to the water pipe, and the heat is liquidized into a small water droplet attached to the outer wall. If the tube wall "sweats", it means that the water vapor content in the air is high and the humidity is large, which is precisely a precursor to rain.是 Cooking food is not the faster the fire. Because the temperature does not change after boiling, even if the firepower is increased, the water temperature cannot be increased. As a result, it can only speed up the vaporization of the water, make the water evaporate in the pot, and waste fuel. The correct method is to boil the water in the pot with high heat, and keep the water boiling with low heat.

⑧ After the water in the kettle in winter is boiled, you can see "white gas" at a certain distance from the mouth of the pot, and the place where the pot mouth is close to the pot nozzle can not see "white qi". This is because the temperature is high in the place where the pot mouth is high, and the water vapor from the pot mouth cannot liquefy, and the temperature of the temperature at a certain distance from the pot mouth is low. Essence

When you fried food, splashing into the water droplets will hear the sound of "Biao, Biao" and splash oil. This is because the boiling point of the water is lower than the oil, and the density of the water is larger than that of oil. The droplets splattered in the oil sink to the bottom of the oil to quickly heat up and boil.

When the pot is boiled in high temperature, sprinkle some water in the pot, and the sound of "squeak, squeak" is made, and a lot of "white gas" is emerged. This is because the water is rapidly vaporized and then liquefied, and the sound of "squeak, squeak". When the soup is boiled, it is overflowing the pan, and quickly add cold water to the pot to the pot to raise the soup to reduce the temperature of the soup below the boiling point. Add cold water, the temperature of the cold water is lower than the temperature of the boiling soup. After mixing, the cold water absorbs heat and the soup is hot. In the process of raising the soup, due to the lower temperature of the air than the soup, the soup is hot and the temperature is reduced. After pouring it into the pot, it absorbs heat from the boiling soup to reduce the temperature of the soup in the pot.

(3) Phenomenon related to the molecular heat movement in thermalology

① Pickled vegetables often take half a month to become salty, and add salt for a few minutes when stir -fry. This is because the higher the temperature, the faster the salt ion movement.

② At the corner of the long -term pile of coal, if a small knife is scraped from the wall with a thin layer, you can see that it is black inside. This is because the molecule never stops doing irregular movements. The molecule spreads to the wall, so it is scraped to see the black inside.

In addition, in the kitchen, if we pay attention to the stoves, utensils, and some phenomena that appear in cooking and cooking, we will find that there are many places to use physical knowledge.

1. During the hot cold porridge or cold rice, the sound of "fluttering and fluttering" in the pot continues to make bubbles, but when it tastes, porridge or rice is not hot. Why?

Heat the cold porridge or rice is different from boiling water. Although water is a poor body, the transmission speed of the heat is very slow, but the water has a good liquidity.当锅底的水受热时，它就要膨胀，密度减小就上浮，周围的凉水就流过来填补，通过这种对流，就把锅底的热不断地传递到水的各部分而使水变hot. The cold porridge or rice is both poor and not easy to conduct heat conduction. Therefore, when the porridge or rice is inhaled at the bottom of the pot, the temperature rises quickly, but it cannot flow up or around quickly. A large amount of heat is concentrated on the bottom of the pot and burnt the porridge at the bottom of the pot. Because the heat is difficult to pass the porridge, the porridge above is still cold. When heating or rice, add more water to the pot to make the porridge thinner and enhance its liquidity. In addition, it is necessary to stir frequently and force the convection, so that the porridge can be evenly heated.

2. "Meeting" in fried meat. In the New Year, people always have to stir -fry a few meat dishes, so how to stir -fry meat?

If the meat slices are directly stir -fry, the water contained in the lean fiber will evaporate sharply, causing the meat to become dry, and even the meat will be burnt, which greatly loses the umami flavor. In order to stir -fried meat slices delicious, the masters often mix the meat slices into an appropriate amount of starch in advance, then the meat slices are placed in a hot oil pan, and the moisture that is attached to the starch paste outside the meat sheet is evaporated. It still maintains the tenderness of the original meat, but also reduces the loss of nutrients, and the meat is cooked and "meets." Frying meat with this method is both fresh and delicious and nutritious.

3. What method is the best method of freezing meat to thaw? How can I thaw it from the refrigerator and frozen chicken?

It is best to use cold water near 0 ° C. Because the temperature of the frozen meat is below 0 ° C. If it is thawed in hot water, the frozen meat absorbs heat from the hot water, and the outer layer quickly thaws and the temperature will rise above 0 ° C, so that the meat layer will have between the meat layers. After the gap, the ability to pass the heat also decreased, making the internal frozen meat not easy to absorb heat and thaw to form a hard core. If the frozen meat is placed in cold water, the temperature of the cold water is quickly dropped to 0 ° C due to the frozen meat and frozen chicken inhale, and some water will be frozen. Because 1 gram of water is made into ice, 80 calories can be released (and 1 gram of water is reduced by 1 ° C for only 1 calories). After so many calories are released, the temperature of the outer layer of the meat is increased rapidly. And the inner layer is easy to absorb heat, so that the temperature of the whole piece of meat will rise to 0 ° C faster. Repeat this repeatedly, frozen meat can be thawed. From the perspective of nutrition, this method of evenly slowly heating up is also scientific

Second, physical knowledge on cars

1. Mechanics

① The quality of the chassis of the car is large, which can reduce the center of gravity of the car and increase the stability of the car when driving. ② The body of the car is designed as a streamlined type to reduce the resistance when the car is driving.

③ The driving force of the car forward -the friction of the ground on the active wheels (the active wheel is opposite to the direction of the friction force of the slave wheel and the ground).

④ When the car is moving forward at a constant speed of the car — the traction and resistance balance each other, and the gravity of the car is balanced with the support of the ground.

⑤ When the car turns:

a. Driver must hit the steering wheel -force is the reason for changing the state of the object;

b. Passengers will fall in the opposite direction of turning -because passengers are inertia.

⑥ When the sudden braking of the car (deceleration),

a. Driver stepping on the brake -force is the reason for changing the state of movement of the object;

b. Passengers will fall in the direction of the car dealers -inertia;

c. The driver can brake the car with a small force -the principle of leverage;

d. Step the brakes hard -increase pressure to increase friction;

e. During the sudden brake, the friction between the wheel and the ground changed from rolling friction to sliding friction.

⑦ The wheels of different uses are still different from the size and number -this is related to the pressure on the road surface of the car.

The seats of the car are designed to be wide and large, which reduces the pressure on the people in the riders and makes people ride comfortably.

When the car is driving quickly, the rear of the car will form a low -pressure area. This is the reason why we often see the rolled dust forming at the tail of the car.

： The requirements of the traffic management department:

a. The driver and the front passengers of the car must be tied to a seat belt -this can prevent the harm of inertia;

b. It is strictly forbidden to overload the vehicle -not only reduce the destruction of the vehicle on the road, but also reduce friction and inertia;

c. It is strictly forbidden to vehicle speed -prevent the car accident due to the reaction distance and the braking distance when the sudden brake is prevented.

： The application of simple mechanical:

a. The steering wheel, wheels, windows and strokes are all wheel axes;

b. The speed adjustment rod, the automatic opening and closing device is lever. Essence

调 When the car climbs, it should be adjusted to a low speed: when P = FV, when the power is certain, the speed is reduced and the traction can be increased.

2. Acoustics

① The sound of the car horn is sounded, and the sound of the engine should be eliminated as much as possible (the engine is equipped with a muffler) -s to weaken the noise at the sound source.

② In order to reduce the impact of the noise of the vehicle on the residents next to the road, a barrier or tree planting is set next to the road -it can weaken noise during the transmission process.

3. Hot science

①The diesel engines or gasoline engines commonly used in automotive engines -they are internal combustion engines -using internal can do work.

② The engine has a water tank, and the circular water is used to help the engine heat dissipation -water is larger than heat.

③ In winter, in order to prevent frozen and bad water tanks, the water in the water tank should be exhausted at night -prevent the dangers of thermal expansion and contraction.

④ The car's rear window glass plate is embedded in the electric wire -it can prevent the fog in the car from attached to the glass and condense.

⑤ When you just sit in a car or have a car from you, you will smell the strong gasoline flavor -spreading phenomenon.

⑥ Air conditioning car window glass is designed with double layers -prevent heat transfer.

⑦Stidoscope using gas fuel can reduce pollution to the atmosphere.

4. Electricity

① The starting of a low -voltage motor of the engine of the car: The motor is made of the principle of the magnetic field on the current, and the electrical energy is converted into mechanical energy during work.

② Automotive motor (automotive motor) is a common vehicle battery (battery) power supply. The wheel that can be used during the car operation can drive the vehicle generator to power the electric machine and charge the battery. When charging the battery, the electrical energy is converted into chemical energy storage. At this time, the battery is an electrical appliance; when the battery is used to power the motor, the chemical energy can be converted into electrical energy. At this time, the battery is the power supply.

③ The vehicle battery is also used to power the air conditioner, fan, inclusion machine, CD machine, and various use electric lights equipped on the car. It is easy to convert electrical energy into mechanical energy, sound energy, light energy, and so on.

④ The tail of the tanker is usually hung directly to the road to the road, which is conducive to the charges caused by bumps during the transportation process to quickly spread to the ground to avoid disasters caused by electrostatic discharge.

⑤ Lighting of car lights: Electricity -Light Energy.

5. Optical aspect

① The rear mirror next to the car and the observation mirror at the intersection are all used with convex mirrors, which can broaden the field of vision.

② When the car is driving at night, the car generally does not turn on the lights. This can prevent passengers from being used to the windshield in front of the driver to imagine the correct judgment of the driver.

③ The windshield in front of the car is usually not upright (except for the high chassis car), which is because of the windshield. It is equivalent to a plane mirror car that is easily imaged in front of the driver through its imaging, affecting the driver's judgment.

④ Car Tail Lightshade: Corner reflectors can reverse the shot light to ensure the safety of the vehicle behind.

⑤ Car headlights: The principle of reflection of the concave surface mirror, close -range light filament near the focus, long -range light filament on the focus.

Third, physical knowledge on bicycles

1. The friction knowledge on the bicycle

① Why do bicycle outer tires have uneven patterns

The size of friction is related to two factors: the size of the pressure and the roughness of the contact surface. The greater the pressure, the greater the friction; the rough the contact surface, the greater the friction. The outer tires of the bicycle have uneven patterns. This increases friction by increasing the degree of roughness between bicycles and the ground. The purpose is to prevent bicycles from slipping. ② Why can bicycles move forward?

When we are riding on a bicycle, because people and bicycles are pressured on the ground, and the tires and the ground are not smooth, there are friction between the bicycles and the road. However, we must ask why the bicycle can move forward? This depends on the friction between the rear wheels and the ground. The direction of this friction is forward. What is the friction of the front wheel? Obstacles to the car! The direction is opposite to the direction of the bicycle. It is these two forces that are equal and the direction is opposite, so the bicycle exercises a uniform speed. However, when people push the bicycle on the ground, the friction direction of the front wheels and the rear wheels is backward.

③ Why can bicycles stop after braking?

During the brake, the friction between the brake and the car rings will hinder the rotation of the rear wheel. The greater the pressure of the hand, the greater the pressure of the brake on the car, the greater the friction produced, and the slower the rear wheels rotate. If you die completely, at this time, the friction between the rear wheels and the ground will become sliding friction (the original rolling friction, the direction forward), the direction is backward, hindering the exercise of the bicycle, so it stops.

④ Where are the steel balls in the bicycle? Why is Ann steel ball?

At the front axis, middle axis, rear axis, handlebars, pedals and other places, there are steel balls.

People always want to be relaxed, flexible and labor -saving. With rolling instead of sliding, you can greatly reduce friction. Therefore, you must install steel balls in the place where the bicycle rotation. We can often add lubricating oil to leave the contact surface with each other, so that the friction force can be smaller.

2. Learning and wheel axis knowledge on bicycles

① leverage on bicycles

a. Control the leverage of the front wheel steering: The handlebars of the bicycle are effortless lever. People can rotate the front wheels of the bicycle with a small force to control the motion direction of the bicycle and the balance of the bicycle.

b. Control the leverage of the brake gates: The handlebar on the handlebar is to save effort, and people can use a small force to press the car gate to press on the steel ring of the wheels with large pressure.

② The axis on the bicycle

a. Paper and flower plate gear: Establish a hard -saving wheel axis (the pedal radius is greater than the radial radius of the flower plate).

b. The bicycle handlebar and the front fork shaft: to form a effortless wheel axis (the radius of the rotating radius of the handle is greater than the radius of the front fork shaft).

c. The gear and rear wheels on the rear axis: form a labor -lilic wheel shaft (the radius radius of the gear is less than the rear wheel radius).

3. Bad pressure knowledge on bicycles

① The inner tires of the bicycle are inflated: the early wheels were wooden wheels and iron wheels. Modern bicycles use inflatable inner tires mainly to increase the pressure in the tire, which can play a buffer, and at the same time can reduce the resistance of the bicycle forward.

② The function of the valve core: The valve core of the inflatable inner tire plays a one -way valve, only allows the gas to enter, prevent the gas from leaking outside, facilitates intake, and ensure the sealing of the inflatable inner tire.

4. Optical knowledge on bicycles

The red taillights on the bicycle cannot shine by themselves, but at night, the driver can remind the driver to pay attention, because the taillights of the bicycle are composed of many honeycomb -shaped "small rooms", and each "small room" is about three to 90 degrees of about 90 degrees. Composition of reflection surface. In this way, when the lights of the car are shot on the taillights of the bicycle, reflex light will be generated. Because the red is eye -catching, the driver's attention can be attracted.

4. Physical knowledge in folk proverbs

In daily life, we often come into contact with some folk proverbs and sayings. These folk proverbs and sayings contain rich physical knowledge. If we usually pay attention to analysis, understand some folk proverbs and sayings, we can deepen knowledge and knowledge in actual life. This is very helpful for cultivating our ability to analyze and solve problems. Here are a few examples:

1. Little is called 斤 斤 小 — According to the principle of leverage balance, if the power arm is one fi of the resistance arm, the power is several times the resistance. If the power arm is very large, then "one or two pounds" is completely possible.

2. Breaking the mirror cannot be re -reunited -when the distance between molecules is large (greater than hundreds), the gravity between molecules is small and almost zero, so the broken mirror is difficult to round up.

3. What can't be taken is the moon in the mirror, what can't be fishing is the flower in the water -the image of the plane mirror is a virtual image.

4. People are in Qi, Mount Tai moves -if the direction of each force is consistent, the size of the joint force is equal to the sum of the size of each force.

5. Tofu tofu can not be lifted -when the pressure is certain, if the area of ​​the force is small, the pressure will be large.

6. Real gold is not afraid of fire, the truth is not afraid of arguing -from the perspective of gold, although it is not the highest, it is also 1068 ° C, and the temperature of the general flame is about 800 ° C. Because the temperature of the flame is less than the melting point of gold, so Gold cannot melt.

7. Moon halo and wind, the foundation and rain -when the wind comes, the temperature in the high altitude drops rapidly, and the water vapor is condensed into a small water droplet. These small droplets are equivalent to many trilogs. Moon halo, so there is a saying "moon halo and wind". The foundation is the anti -tide of the ground. Before the heavy rain comes, the air humidity is large, the ground temperature is low, and the water vapor near the ground is condensed as a small water droplet. The rain is coming. 8. Long howling, mountaining valley — a long howling in the mountains and mountains, and the sound through multiple reflexes can form a bright echo. It is endless. It seems that the mountain is exhaling and the valley is in the echo.

9. But smelling its sound, no one person -in the process of spread, when the size of the obstacles is smaller than the wavelength, obvious diffraction can occur. Generally, the height of the fence is a few meters, and the wavelength of the sound waves is larger than the height of the wall. Therefore, it can hear the high wall around the ground and hear the people outside the wall. The light emitted cannot be diffused outside the wall, and people outside the wall cannot see people inside the wall.

10. Do not sound boiling water, no sound of water -before the water boils, due to the current flow, the air bubbles in the water rises while vibrating, and most of the air bubbles are ruptured under the pressure of the water. So the sound is loud. After the water is boiling, the temperature is equivalent, the volume of the bubbles increases, and it rises to the surface of the water under the effect of buoyancy, so the sound is relatively small.

11. Pig Bajie photos of the mirror, not human inside and outside -according to the law of the image imaging of the plane mirror, the image of the flat mirror is equal, and the objective image is symmetrical. It's not a person inside and outside. "

12. Water and fire are not compatible -material combustion must reach the fire point. Due to the heat of water, water and fire can absorb a large amount of heat to reduce the temperature of the fire matter. At the same time It makes it impossible for objects to contact the air, and without air, burning cannot be performed.

13. One day in the cave, it has been a thousand years in the world -according to Einstein's theory of relativity, the passing of time is much slower than the earth's spaceship, and the passage of time will be much slower than the earth. It has been spent for several years, decades, or even hundreds of years, thousands of years.

14. Thousands of miles, Shunfeng Ear -people use electromagnetic wave to transmit sound and image signals to make the "thousands of eyes eyes, Shunfeng ears" in ancient mythology into reality. And human vision has far exceeded "thousands of miles".

15. Eighty miles a day -to -sit on the ground -because the radius of the earth is 6370 kilometers, every time the earth turns around, the "walk" on the surface is about 40003.6 kilometers, about 80,000 miles. This is Mao Zedong's poems, and it also scientifically reveals the relationship between exercise and static -movement is absolute, and still is relatively relative to reference objects.

16. Salary at the bottom of the kettle -there are two conditions for liquid boiling: one is to reach the boiling point, and the other is to continue to absorb heat. If "salary" can stop the boiling liquid.

17. Flower in the wall in the wall -Due to the continuous movement of irregular movements, the floral fragrance in the wall will spread to the outside of the wall.

18. Sitting in the well, we see very little -because of the spread of light along the line, the knowledge of the geometry can be seen that the horizons of frogs will be small.

19. If you sit on the needle -by the pressure formula, you can know that when the pressure is certain, the smaller the force area, the larger the pressure. When people sit on such a felt, they feel very uncomfortable.

20. Ruixue Zhaofeng -There are many loose gaps to the ground, full of air that is full of non -flowing air. Therefore, it can play a role in heat preservation.

21. Cold before frost, cold after snow -In the late autumn night, the air temperature near the ground suddenly became cold (temperature below 0 ° C), water vapor in the air condensed into small ice crystals, attached to the ground to form cream , So there is a feeling of "Frost". It is necessary to absorb heat during snow melting and reduce the temperature of the air, so we have the feeling of "after snow".

22. A drop of water can be seen in the sun. One thing to see -a drop of water is equivalent to a convex lens. According to the rules of the rectification of the convex lens, there is a image of the sun through a drop of water.

23. The large ship leaks water -there is no stress inside the liquid. After the ship is broken, the water outside the ship is pressed into the ship until the water surface inside and outside the ship is flat. At this moment, the water inside the ship will not flow outward.

24. The fire in the paper -will burn when the paper reaches the burning point.

25. There is a natural fragrance of musk, why do you need to welcome the wind -the diffusion of the gas.

26. When the jade is not carried, the jade is uneven before the jade is grinded, the light reflection occurs, and after the jade is grinded, the surface is smooth, and the light occurs in the light.

27. The fan has a cool breeze, and the summer is not suitable for winter -when the fan is fan in summer, the flow of air is accelerated, and the sweat on the surface of the human body is accelerated. Because it evaporates heat, people feel cool. 28. People go to high places, and water flows to low places -water flowing to low places is a objective law in nature.

29. Water tank sweats, no need to carry -the water in the water tank due to evaporation, the temperature below the water surface is lower than the air temperature, and the water vapor in the air encounters a liquefied phenomenon. Attached to the outside of the water tank. Due to the small water vapor content in the air in a sunny day, although the surface of the water tank is also liquefied, the trace liquefaction quickly evaporates again, and the water drops cannot be formed. Slow, the liquefaction on the outer surface of the water tank is greater than vaporization, and there are water drops. The water vapor content in the air is large, and the possibility of rainfall is high. Of course, there is no need to pick water to pour water.

30. It does not cause cold snow and cold -snow is formed by the water vapor of water vapor or water droplets in high altitude. The condensation and solidification are the heat insulation process. The snow is the melting process.

31. Snow falls into the mountains, frost drops plains -snowy days, the temperature of the mountain is lower than the lower level of the mountain, and the snow from the mountains is not easy to melt. Many. Frost is the result of condensation on the water vapor on the ground. The water vapor on the surface of the mountain on the ground under the mountain is more than the mountains, so it is easy to mix in the flat ground, and the high mountains are not easy to form cream.

32. Frozen three, not a day's cold -the temperature of the water is between 0 ℃ and 4 ℃, the density of the water is the most at 4 ° C. When the whole water temperature drops to 4 ° C, the water is water, the water is on, the water is on, the water is on, the water is on, the water is on, the water is water, and the water is water. When the flow stops. When the temperature continues to decline, the water temperature of the upper layer drops below 4 ° C, the density decreases no longer sinking, the water temperature of the bottom layer remains 4 ° C, when the water temperature of the upper layer drops to 0 ° C and the water surface will be freezing. Because the water begins to freeze. Due to the water, because the water starts to freeze. Due to the water, the water starts to freeze. Because the water starts to freeze. Because the water starts to freeze. Due to the water, because the water starts to freeze. Due to the water, because the water starts to freeze. Due to the water, because the water starts to freeze. Due to the water, the water starts. He ice is a bad conductor, and the smooth and bright ice surface can prevent radiation. Therefore, the three methods of heat transfer are not easy to perform. The heat of water under ice is extremely slow. Long time cold.

33. There must be winds next to the fire field -the air near the fire field is heating up, and the cold air in the distance will be filled in the future, and the flow of hot and cold air will form wind.

34. One stone cut into the water in the water -the calm water surface is like a plane mirror. You can see the image of the sky. The stone is put into the water to destroy the calm water surface and form a layer of water waves.

35. Blindly lights white fees -people can see all things in the world because the light of the sun or the light used to light the light that the light reflected by the object into the eye enters the human eye. No objects.

36. Early rainbow raindrops, late rainbow exposure -the rainfall in our country is mostly moved from west to east. The rainbow seen in the morning is the west formed by the sunlight shot on the western rain layer in the west. Obviously, Western Rainbow is the foresteps that will rain in the local weather. On the contrary, the rainbow seen in the evening is a east rain formed by the sun shining on the water droplets of the western sky rainfall. The clouds must be sunny.

37. Chaoxia does not go out, the sunset goes thousands of miles- (reference to the first)

38. Rainbow high sun heads are low, and morning and evening wear -when "low sun heads", the sunlight and horizon are very close. At this time, the rainbow, the heart of the rainbow must be close to the horizon. You can see the rainbow on the ground. Half of the arc. If there is a lot of water droplets in the air at this time, and the distribution is wide, then in addition to seeing the rainbow, you can also see the neon. The rain clouds have moved near the sky, and the local heavy rains soon declined.

39. The negatives of the photo -reversing black and white -camera is made of the application object in two times the focal length of the convex lens, and the real image principle that is reduced to the reducing and reduced. Therefore, the image on the film is upside down. The negatives are coated with a sensor. When the person is illuminated, due to the strong ability to reflect light in the light parts, the reflected light enters the dark box of the camera and the sensor on the negatives. There are only few reflective light shot into the negatives. In this way, the light -colored parts are strong on the film, and the dark parts are weak. When the film is washed, the sensor of the weak light is washed away. Due to the occurrence of optical reactions, the site is dark.

40. Do not cut the firewood by mistake -reduce the pressure to increase the pressure.

41. Eggs touch the stones -self -impatient force -the eggs touch the stones. Although the size of the force is the same, the pressure that each object can withstand must be, exceeding this limit, the object may be damaged. Eggs can bear the small pressure, so the eggs will break.

42. One slap does not ring -force is the role of objects on objects. One slap either shoots the other slap or shoots on other objects to produce force to make a sound.

43. Four or two pounds -the balanced conditions of leverage, increase the ratio of power arm to resistance arm, and only need to use smaller power to pry up heavy objects.

44. Mercury landed -pervasive -mercury density is greater than the density of the material of the ground, and mercury is liquid, so it always sinks under the other material.

Wait a one -button three consecutive ~

- END -