1. Phenomenon related to electrical knowledge 1. Cooking in an electric cooker, cooking in an electric wok and boiling water in an electric kettle all use electric energy to convert into internal energy, and all use heat transfer to cook, cook and boil water.
2. The exhaust fan (range hood) converts electric energy into mechanical energy, and air is converted by air convection. 3. Insert the three-pin plug of the rice cooker, electric frying pan and electric kettle into three hole socket to prevent electric leakage and electric shock.
4. The microwave oven has the advantages of uniform heating, high thermal efficiency and no pollution. The heating principle is to convert electric energy into electromagnetic energy, and then convert electromagnetic energy into internal energy.
The electric light in the kitchen works by converting electric energy into internal energy and light energy by the thermal effect of current. 6. Kitchen stoves (honeycomb coal stoves, liquefied gas stoves, coal stoves and wood stoves) convert chemical energy into internal energy, that is, fuel burns to release heat.
Second, the phenomenon related to mechanical knowledge 1, the spout and belly of the electric kettle form a communication device, and the water surface is always flat. 2. The thin edge of the kitchen knife is to reduce the stress area and increase the pressure.
3, the blade of the kitchen knife has oil, in order to cut vegetables when the contact surface is smooth, reduce friction. 4. The handle, spatula handle and electric kettle handle have convex and concave patterns, which make the contact surface rough and increase friction.
5, fire shovel to send coal, is to use the inertia of coal to send coal into the furnace. 6. Pour boiling water into the thermos bottle and know the water level according to the sound.
Due to the increase of water volume, the length of air column decreases, the vibration frequency increases and the tone increases. 7. Keep watering when grinding the kitchen knife, because the heat generated by the friction between the kitchen knife and the stone increases the internal energy of the knife, the temperature rises, the hardness of the knife edge becomes smaller, and the knife edge is unfavorable; Watering is to use heat transfer to reduce the internal energy and temperature of the kitchen knife without rising too high.
Phenomena related to thermal knowledge (1) Phenomena related to thermal expansion and heat transfer in thermal 1 When boiling water or cooking with a stove, put the bottom of the pot on the outer flame of the flame, and don't let the bottom of the pot press the burner, because the temperature of the outer flame of the flame is high, which can make the temperature of the pot rise rapidly. 2, spatula, spoon, colander, aluminum pot and other cookware handles are made of wood, because wood is a poor conductor of heat, so it will not heat up during cooking.
3. The purpose of installing an exhaust fan above the cooker is to speed up air convection, so that kitchen fumes can be discharged in time to avoid polluting the space. 4. The hot casserole is easy to break on the wetland.
This is because casserole is a bad conductor of heat. When the casserole is placed on the wetland, the outer wall of the casserole shrinks quickly, and the temperature of the inner wall drops slowly. The casserole shrinks unevenly inside and outside and is easy to break. 5. When the thermos bottle is filled with boiling water, it can be better insulated without it.
Because there is a layer of air in the bottle mouth when it is not filled, it is a bad conductor of heat, which can better prevent heat loss. 6. Cooking mainly uses heat conduction to transfer heat, while cooking and boiling water mainly use convection to transfer heat.
7. Pour some boiling water from the thermos in winter. When you cover the cork tightly, you often see the cork jump up at once. This is because when boiling water is poured out, some cold air enters, and after the cork is plugged, the cold air enters expands rapidly when heated, and the pressure increases, thus pushing the cork away.
8. For the hot soup that just comes out of the pot in winter, it seems that the soup is not hot, but it tastes very hot because there is a layer of oil on the noodle soup that prevents the heat loss (water evaporation) in the soup. 9. In winter or when the temperature is very low, pour boiling water into the glass, and preheat the glass with a small amount of boiling water first, so as to avoid the excessive temperature difference between the inside and outside of the glass, and the thermal expansion of the inner wall is hindered by the outer wall, resulting in the glass breaking.
10. Boiled and scalded eggs are easy to shell when soaked in cold water for a while. Because hot eggshells and protein contract when they are cold, the degree of contraction is different, so they are separated.
2. Kneel for 50 common knowledge of physics in life ~ ~
This is the teacher's original words.
1 Snow is not as cold as Leng Xue.
2. White air that speaks in winter is small water droplets liquefied by water vapor.
Rub a little alcohol on your skin and you will feel cold. This is because when alcohol evaporates, it absorbs heat from your body and makes your skin feel cold.
Incandescent light bulbs that have been used for a long time will be black because the tungsten filament sublimates when heated, and then the tungsten filament gas condenses on the bulb wall, so the incandescent light bulbs that have been used for a long time will be black.
When drinking boiled water, if you feel boiled water is hot, you will generally blow air into the water surface, because the temperature will decrease when the liquid evaporates, which means that the liquid evaporation has a cooling effect. Blowing air on the water surface can speed up the air flow on the water surface. The faster the air on the liquid surface flows and evaporates, the faster the water temperature will drop and the hot water will not burn.
In winter in the north, when a person wearing glasses walks into a warm room from the outside, a layer of water droplets will appear on the lens. Because the glasses are cold outside, when entering a warm room, the water vapor contained in the indoor air will liquefy (condense) into small water droplets and adhere to the lens.
7. What you can't catch is the flower in the water that you can't catch in the mirror: that's because the flat mirror makes a virtual image.
8. "True gold is not afraid of fire, and truth is not afraid of argument." Judging from the melting point of gold, although it is not the highest, it is 1068℃, while the temperature of general flame is about 800℃. Because the temperature of the flame is lower than the melting point of gold, gold cannot be melted.
Long whistle, mountain sounds like valleys: people long whistle in the mountains, and the sound can form a loud echo after repeated reflection, which lasts for a long time. As if the mountains were shouting and the valleys were echoing.
10 Pig Bajie looks in the mirror-it's not human inside and outside: according to the imaging law of plane mirror, the images formed by plane mirror are equal in size and the objects are symmetrical, so what Pig Bajie sees is "exactly the same" as himself, and it's still the image of a pig. Naturally, it's not human inside and outside.
1 1. Looking at the sky from the well, we can see very little: because light travels along a straight line, from the knowledge of geometric drawing, the frog's field of vision will be very small.
12 Xue Rui shines brilliantly: Because snow is a poor conductor of heat, when it covers crops, it can well prevent heat conduction and air convection, so it can play a role in heat preservation.
13, "A drop of water can see the sun, but a thing can see the spirit." A drop of water is equivalent to a convex lens. According to the law of convex lens imaging, you can see the image of the sun through a drop of water.
14, "Fans have a cool breeze, which is suitable for summer but not winter." When the fan is used in summer, the air flow is accelerated, which makes the sweat on the human surface evaporate quickly. Because evaporation absorbs heat, people feel cool.
15. Before the jade is polished, the surface of the jade is uneven and the light is diffuse. After the jade is polished, the surface is smooth and the light is mirrored.
16 Boiled and scalding eggs are easy to shell when soaked in cold water for a while. Because hot eggshells and protein contract when they are cold, the degree of contraction is different, so they are separated.
17 watering can cool down? -Due to the heat absorption of water vapor evaporation, the ambient temperature is reduced.
18 summer water pipe' sweating' is due to the hot air in the cold water pipe, which is liquefied into water droplets when it is cold, covering the water pipe wall.
19 jiaozi will float to the surface after being cooked, with lower density, larger volume and greater buoyancy.
Soap bubbles are colorful because of the refraction of light.
2 1. The beautiful white sail is reflected in the lake because of the reflection of light.
Chopsticks are "broken" because of the refraction of light.
When watching a movie, you can see the picture on the screen from all angles because the screen diffuses light.
24. Oily vegetable soup is not easy to cool, because the oil layer covers the soup surface, which hinders the evaporation of water.
When boiling water or cooking food, the steam emitted is more serious than hot water or hot soup. Because when steam turns into hot water or soup with the same temperature, it will release a lot of heat (liquefaction heat).
I'm also in grade two. I can't help it I've racked my brains to give you so much. I hope it helps you! ! !
3. Physical phenomena in life 50 words
1, quartz clock hanging on the wall, when the battery runs out and stops, its second hand often stops at the position of "9" on the dial. This is because the second hand is most hindered by the large torque at the "9" position.
2. Sometimes, when tap water flows from the adjacent faucet, it occasionally makes bursts of noise. This is because the water pipe vibrates when the water rushes out of the tap.
3. When taking pictures in front of the TV screen, turn off the camera flash and indoor lighting to make the pictures clearer. Because the reflected light of the flash lamp and the illuminating lamp on the TV screen will interfere with the transmitted light of the TV picture.
At the same temperature, frozen pork thaws faster in water than in air. At the same temperature, hot nails cool faster in water than in air. A cup filled with boiling water cools faster when immersed in water than when immersed in air at the same temperature. All these phenomena show that water has better heat transfer performance than air,
When the pot is filled with cold water, the water droplets attached to the outer surface of the pot bottom can only be dried on the flame for a long time, and then they will boil. This is because the water droplets, the pot and the water in the pot keep heat conduction, and the temperature is similar. As long as the water in the pot is not boiled, the water droplets will not boil, but will evaporate on the flame and gradually dry up.
6. Distorted mirror, the farther people are from the mirror, the more distorted they are. Because the image in the mirror is formed by the reflection of the silver-plated surface behind the mirror, uneven silver-plated surface or uneven glass thickness will lead to aliasing. The farther away from the deformed mirror, the more the reflected light on the silver-plated surface deviates from the normal position according to the principle of light amplification, and the more deformed the mirror is.
7. There are several small holes communicating with the outside world on the side of the gas nozzle of the natural gas furnace, but natural gas will not be ejected from the side holes, but only from the nozzle. This is because the air velocity at the nozzle is high, and according to the principle of fluid mechanics, the air surface pressure is lower than the atmospheric pressure outside the side hole, so the natural gas will not be ejected from the side hole of the nozzle.
8. After blowing the balloon, hold the mouthpiece with your hand and then suddenly release it. The air in the balloon is ejected and the balloon moves due to recoil. You can see that the route of balloon movement is tortuous. There are two reasons: first, the thickness and tension of the inflated balloon are uneven everywhere, which makes the balloon contract unevenly and swing around when it is deflated, thus the movement direction changes constantly; Second, the shape of the balloon is constantly changing during the contraction, so the air velocity on the surface of the balloon is also constantly changing during the movement. According to the principle of fluid mechanics, the air pressure on the surface of the balloon is constantly changing, so the balloon swings and the direction of movement is also constantly changing.
9. When the ceiling fan rotates normally, the tension at the suspension point is smaller than when it does not rotate. The greater the rotational speed, the more the tension decreases. This is because when the ceiling fan rotates, the air has an upward reaction force on the ceiling fan blades. The greater the speed, the greater the reaction.
10, electric furnace "combustion" is the conversion of electric energy into internal energy. Without oxygen, it can only oxidize electric furnace wires, shortening service life.
1 1. Even if there is no wind, the path of paper dropping is tortuous. This is because each part of the paper has different convexity and concavity and shape, so in the process of falling, the air speed on its surface is different. According to the principle of fluid mechanics, there is uneven air force everywhere on the paper, which changes with the movement of the paper, so the paper keeps rolling and falling zigzag.
4. Physical tips
Question 1: Why did jiaozi sink when he was first poured into the pot?
* Question 2: Why does jiaozi float when cooking, and only jiaozi floats when cooking?
* Question 3: Why did jiaozi sink into the bottom of the pot after it cooled down?
Okay, can you answer that? Let's take a look at the mystery!
It turns out that with the heating of the stove, the water and jiaozi in the pot are heating up slowly. Objects will expand when heated, and jiaozi and water are no exception. But the degree of thermal expansion of different objects is different: some expand quickly, and some expand slowly. Jiaozi expands faster than water, so their volume can easily increase a lot. (Cooked jiaozi is generally full, much bigger than raw jiaozi. However, the weight of jiaozi did not increase. After the volume increased, the weight per unit volume, that is, the density decreased. According to Archimedes principle, we can know that the buoyancy of an object immersed in a liquid is equal to the weight of the same volume of liquid. After jiaozi is cooked, the stuffing and skin of dumplings are fully expanded. At this time, the density of jiaozi is less than that of water, and the weight of jiaozi with the same volume is less than that of water with the same volume. According to Archimedes principle, the buoyancy of jiaozi immersed in water is equal to the weight of the same volume of water. So the buoyancy of jiaozi is greater than its own weight, and jiaozi floats. Therefore, jiaozi can only float if it is cooked, that is, the dumpling stuffing and dumpling skin are fully expanded. Eat jiaozi float, of course, there will be no worries.
Why did jiaozi sink when it was a little cooler after it floated? A rapidly expanding object will contract rapidly. When water cools, jiaozi shrinks much faster than water. In this way, after jiaozi contracts, the weight per unit volume increases and the buoyancy of water decreases. The reduced buoyancy was no longer enough to make jiaozi, whose weight per unit volume increased, float, so jiaozi sank to the bottom of the pot again.
You see, there are so many reasons for the ups and downs in jiaozi! To explain these truths, we need to learn more about science and culture. Readers, let's study hard together!
5. Little common sense of physical life
1. Electrical knowledge 1. Cooking in an electric cooker, cooking in an electric wok and boiling water in an electric kettle all use electric energy to convert into internal energy, and all use heat transfer to cook, cook and boil water.
2. The exhaust fan (range hood) converts electric energy into mechanical energy, and air is converted by air convection. 3. Insert the three-pin plug of the rice cooker, electric frying pan and electric kettle into three hole socket to prevent electric leakage and electric shock.
4. The microwave oven has the advantages of uniform heating, high thermal efficiency and no pollution. The heating principle is to convert electric energy into electromagnetic energy, and then convert electromagnetic energy into internal energy.
5. Kitchen stoves (honeycomb coal stoves, liquefied gas stoves, coal stoves and wood stoves) convert chemical energy into internal energy, that is, fuel burns to release heat. Second, mechanical knowledge 1, the thin edge of the kitchen knife is to reduce the stress area and increase the pressure.
2. The handle, spatula handle and electric kettle handle have convex and concave patterns, which make the contact surface rough and increase friction. 3. Pour boiling water into the thermos and know the water level according to the sound.
Due to the increase of water volume, the length of air column decreases, the vibration frequency increases and the tone increases. 4. Keep watering when grinding the kitchen knife, because the heat generated by the friction between the kitchen knife and the stone increases the internal energy of the knife, the temperature rises, the hardness of the knife edge becomes smaller, and the knife edge is unfavorable; Watering is to use heat transfer to reduce the internal energy and temperature of the kitchen knife without rising too high.
Three, thermal knowledge 1, spatula, spoon, colander, aluminum pot and other cookware handles are all made of wood, because wood is a poor conductor of heat, so it will not heat up during cooking. 2. When the thermos bottle is filled with boiling water, it can be better insulated without it.
Because there is a layer of air in the bottle mouth when it is not filled, it is a bad conductor of heat, which can better prevent heat loss. Pour some boiling water from the thermos in winter. When you cover the cork tightly, you often see the cork jump up at once.
This is because when boiling water is poured out, some cold air enters, and after the cork is plugged, the cold air enters expands rapidly when heated, and the pressure increases, thus pushing the cork away. 4. When boiling water or cooking food, the sprayed steam burns more seriously than hot water or hot soup.
Because when steam turns into hot water or soup with the same temperature, it will release a lot of heat (liquefaction heat). 5, cooking food is not the faster the fire.
Because the temperature of water remains unchanged after boiling, even if the firepower is increased, the water temperature cannot be raised. As a result, it can only accelerate the evaporation of water, make the water in the pot evaporate and waste fuel. The correct way is to boil the water in the pot with a big fire, and then keep the water boiling with a small fire.
6. Boil hot eggs in cold water for a while, which is easy to shell. Because hot eggshells and protein contract when they are cold, the degree of contraction is different, so they are separated.
Baidu Encyclopedia-China Ancient Thermal Knowledge.
6. A little knowledge of physics
I'm sorry.
It looks like that. .. it's really hard.
.. embarrassed, embarrassed. In addition, contact in advance will cultivate your interest in learning ... these are junior high school students.
You will see. .. 1. A moving bicycle will stop after braking. What is the reason why the bike stopped? Answer: The friction between the moving bicycle wheel and the ground is rolling friction. After braking, the wheel is not easy to rotate, and the friction between the wheel and the ground becomes sliding. Sliding friction is much greater than rolling friction, so the bike will stop.
2, knowledge points: when measuring the length, we must estimate the next smallest scale. 3. Knowledge point: The height of the mercury column is the vertical distance from the upper surface of the mercury column in the glass tube to the mercury surface in the mercury tank. Therefore, when the glass tube is tilted, the length of the mercury column becomes larger, but the height remains the same.
4. An object moves in a straight line at a uniform speed on two horizontal planes with the same length but different roughness. The work done on the smooth section is W 1, and the work done on the rough section is W2. Find the relationship between W 1 and W2. Answer: W 1=W2 5. A small ball was placed on the smooth floor of the carriage. When the frame is subjected to a horizontal force F to the right, the frame accelerates from standstill. What is the movement of the ball on the ground during the movement? Answer: Still.
6. Two solid cylinders A and B are placed on the horizontal ground, and their pressure on the ground is equal (the bottom and height of A are smaller than that of B), so who has the greater density and gravity? Answer: A university. A small glass.
7. This scale measures the length of an object three times. 50CM, find the minimum scale value of this scale.
Answer: 0. 1CM 8. Knowledge point: evaporation only occurs on the surface of liquid, while boiling occurs both on the surface and inside. Evaporation is mild and boiling is intense. Evaporation can occur at any temperature, but boiling can only occur when it reaches a certain temperature. The temperature of evaporation itself and its surroundings decreases, and the boiling temperature remains unchanged. 9. Knowledge points: temperature-internal energy (certain)-internal energy-temperature (not necessarily)-heat (not necessarily)-internal energy (certain) The plus or minus of temperature and heat is not necessarily 10. Knowledge points: Characteristics of power stroke: spark plug ignition, piston moving down, rotating shaft moving left, no air intake, no exhaust.
1 1, knowledge point: convex lens: when the object distance is within a focal length, the object distance becomes smaller, the image distance becomes smaller, and the image becomes smaller. When the object distance is greater than a focal length, the object distance increases, the image distance decreases and the image becomes smaller.
When the object distance is a focal length, no imaging is performed. 12. In the parallel circuit, as long as one more resistor is connected in parallel, the total resistance will decrease regardless of the size.
In series circuit, if a resistor is connected in series, regardless of its size, the total resistance will inevitably increase. 13. How to study the relationship between conductor resistance and conductor length with two resistance wires with the same length and different thickness? Answer: Use a resistance wire to fix one end of the wire, and the other end slides on the resistance wire to compare the resistance.
14, a person standing on a dry wooden bench, holding the live and zero wires in both hands, measuring his hands and skin with a pencil. The neon lights are shining, but this person is very nice. What is the reason? Answer: Someone has disconnected the zero line. 15. I saw fish flying in the sky and birds swimming in the water somewhere. What is the reason? Answer: Fish is a virtual image formed by light refraction, and birds are a real image formed by light reflection.
16. What sports can astronauts do under the condition of complete weightlessness? Answer: For example, exercise with a spring dynamometer. Running and pull-ups on the treadmill are not allowed.
17. Are the gravity of the car and the supporting force of the ground on the car interactive or balanced? Answer: balance force. 18, knowledge point: the connector is a container with only an upper opening and a connected bottom.
Principle: When there is only one liquid in the communication device and it does not flow, the liquid level of each container is horizontal. 19. When doing the Torricelli experiment, the measured atmospheric pressure is smaller than the true value. Why? A: There is a small amount of air mixed in the glass tube.
20. A container with a thick bottom and a thin top is filled with water. The pressure of water on the ground of the container is 15N. Then, put a wax block weighing 2N in the container, and the wax block will float, so that water will not overflow the container. What is the relationship between the pressure of container ground water and the size of 17N? Answer: greater than 17N. 2 1. When an ice cube is put into isothermal water, its gravity is greater than its buoyancy. How does the water level change when the ice melts completely? Answer: Up.
22. Knowledge point: Doing work must meet the requirements: a strong force acts on the object, and the object passes a distance along the direction of the force. 23. Someone wants to lift a 5N object1m. What did he do the least? 1, unarmed 2, movable pulley 3, inclined plane 4, crown block? Answer: unarmed.
24. What mechanical energy does a naturally elongated spring have? Answer: No. 25. Scene: Yunnan Crossing the Bridge Rice Noodles.
Find physical phenomena and explain them. Answer: 1 does not emit hot air: oil slows down the evaporation of water; 2 forming oil film: the density of oil is smaller than that of air.
3. The meat is cooked: there is heat transfer between the soup and the meat. 26. Knowledge point: Doing work and heat transfer are equivalent in increasing the internal energy of an object.
27. Xiaogang took a beautiful underwater photo with his camera. After the water was drained, Xiaogang did not move. Should he stretch the camera forward or backward? Answer: backward. 28. What happens when a fly stops in front of the camera lens to take pictures? Answer: There are no flies, but it will be darker.
29. Xiaogang wants to verify whether his rubber ball is elastic or Xiaoming's. Can he? Answer: If you drop two balls at the same height, the rebound is high and the elasticity is good. 30. What is the difference between inserting an iron core and a steel core in an electrified bobbin? Answer: Iron can be demagnetized immediately after power failure, but steel can't.
3 1, electromagnetic waves are mainly used for? A: Disseminate information. 32. Does nuclear energy come from the sun? Answer: No.
A car (gasoline) and a tractor broke down on the expressway. After inspection, the battery is broken and cannot be started. At this time, someone asked, what car can run after pushing them? Answer: Tractor. 34. Knowledge points: The geomagnetic south pole is near the geographical north pole, and the geomagnetic north pole is near the geographical south pole.
35. A wooden block A floats on the water and an iron block B is placed on it. Both blocks of wood and iron are above the water. The volume of wood blocks immersed is V 1. Take the iron from A and put it in the water. The displacement of wood blocks and iron blocks is V2. It is known that V 1-V2=4 cubic decimeters, and the volume of A is 8 cubic decimeters. Answer: 40N 36. Pull an object with a bottom area of 200 square centimeters 100N on a horizontal plane. What is the resultant force on the object? What is the ground pressure? Answer: 0. 3000 pa.
37. Be a Conservative party member.
7. 50 words for politics, 50 words for history, 50 words for physics, 50 words for chemistry, 50 words for biology and 50 words for geography.
Politics: this semester, we will strengthen the consolidation of basic knowledge and improve our scores on the basis of basic improvement.
Ensure that you can listen carefully in each class and finish your homework carefully after class. Spend another 29 minutes every day reciting relevant content, or reviewing previous content.
I hope I can improve by about five points in every exam. History: recite the test sites, listen carefully in each class and finish your homework carefully.
Spend 20 minutes every day getting familiar with the text, looking up the chronology of events and remembering the contents above. Try to master all the test sites.
I hope my history score can be improved by five points every time this semester. Physics: this semester, we will strengthen the consolidation of basic knowledge and improve our scores on the basis of basic improvement.
Ensure that you can listen carefully in each class and finish your homework carefully after class. Spend another 20 minutes every day reciting formulas, looking at test sites and examples.
Do a set of wrong questions well and don't do it again. I hope I can improve by about five points in every exam.
Chemistry: this semester, we will strengthen the consolidation of basic knowledge and improve our scores on the basis of basic improvement. Ensure that you can listen carefully in each class and finish your homework carefully after class.
Spend another 20 minutes every day reciting formulas, looking at test sites and examples. Do a set of wrong questions well and don't do it again.
I hope I can improve by about five points in every exam. Biology: lay a solid foundation and improve the score on the basis of improving the foundation.
Ensure that you can listen carefully in each class and finish your homework carefully after class. Spend another 20 minutes every day reciting formulas, looking at test sites and examples.
Do a good job of collecting wrong questions and don't make the mistake of Shanghai warehouse. I hope I can improve by about five points in every exam.
Geography: this semester, we will strengthen the consolidation of basic knowledge and improve our scores on the basis of basic improvement. Ensure that you can listen carefully in each class and finish your homework carefully after class.
Spend another 20 minutes looking at the map every day, memorize the characteristics of each place and remember the relevant contents. Do a set of wrong questions well and don't do it again.
I hope I can improve by about five points in every exam.