Physics is more and more widely used in people's daily life and production. It can be said that physics is being processed everywhere. Take the kitchen where people live together day and night as an example, which contains rich physical knowledge. We carefully observe the whole process of cooking, cooking and cooking in the kitchen, and recall a series of changes in the kitchen, and we will see related physical phenomena, including those related to electrical knowledge, mechanical knowledge and thermal knowledge. In our daily life, we take some things for granted and people know them, but do we have an essential understanding of why these phenomena happen, how they happen and why they have such a result? Next, based on the observation of kitchen phenomena and previous experience, and according to some information I learned in physics and searched online, I made some explanations and explanations for some phenomena. Keywords: kitchen; Physics; Electricity; Mechanics; Keywords Thermodynamics There is a lot of physical knowledge in the kitchen, some of which I haven't discovered yet, and some of which I can't explain just by knowledge. Not only is the kitchen related to physics, but there is knowledge of physics everywhere in daily life. Let's explore together. 1, phenomena related to electrical knowledge 1. 1 Cooking in an electric rice 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 to transfer cooking, cooking and boiling water. 1.2 exhaust fan (range hood) converts electric energy into mechanical energy, and uses air convection to convert air. 1.3 plug the three pins of the rice cooker, electric frying pan and electric kettle into three hole socket to prevent electric leakage and electric shock. 1.4 The microwave oven has the advantages of uniform heating, high thermal efficiency, sanitation and no pollution. The heating principle is to convert electric energy into electromagnetic energy, and then convert electromagnetic energy into internal energy. 1.5 The electric lamp in the kitchen works by converting electric energy into internal energy and light energy by the thermal effect of current. 1.6 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. 2. Phenomenon related to mechanical knowledge 2. 1 The spout and belly of the electric kettle form a communication device, and the water surface is always flat. 2.2 The thin blade of the kitchen knife is to reduce the stress area and increase the pressure. 2.3 The blade of the kitchen knife has oil, in order to cut vegetables with smooth contact surface and reduce friction. 2.4 The handle, spatula handle and electric kettle handle have convex and concave patterns, which make the contact surface rough and increase friction. 2.5 When the fire shovel delivers coal, the inertia of coal is used to deliver the coal to the furnace. 2.6 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. 2.7 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. 3. Phenomena related to thermal knowledge 3. 1 3. 1 Phenomena related to thermal expansion and heat transfer 3. 1. 1 When boiling water or cooking with a stove, the bottom of the pot should be placed outside the flame, so that the temperature of the pot can rise rapidly because of the high temperature of the flame. 3. 1.2 The handles of cookers such as spatula, spoon, colander, aluminum pot, etc. are all made of wood, because wood is a poor conductor of heat, so as to avoid heating during cooking. 3. 1.3 The purpose of installing an exhaust fan above the cooker is to speed up air convection, so that the kitchen fume can be discharged in time to avoid polluting the space. 3. 1.4 Boiling casseroles are easily broken in wetlands. This is because casserole is a bad conductor of heat. When the casserole is placed on the wetland, the outer wall of the casserole will shrink rapidly, the temperature of the inner wall will drop slowly, and the casserole will shrink unevenly inside and outside, which is easy to break. 3. 1.5 When the hot water bottle is filled with boiling water, it can be better insulated without filling 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. 3. 1.6 Heat conduction is mainly used for cooking, and convection is mainly used for cooking and boiling water. 3. 1.7 pour some boiling water from the thermos in winter. When you close the cork, you will 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. 3. 1.8 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, which prevents the heat loss (water evaporation) in the soup. 3. 1.9 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 that the temperature difference between the inside and outside of the glass is too large, and the outer wall hinders the thermal expansion of the inner wall, resulting in the glass breaking. 3. 1. 10 Boiled and scalded eggs are easy to shell when soaked in cold water for a while. Because hot egg shells and egg whites contract when they are cold, the degree of contraction is different, thus separating them. 3.2 Phenomenon related to the change of object state 3.2. 1 Liquefied gas is compressed and liquefied at room temperature and then put into steel cans; When in use, liquefied gas is decompressed by the pressure reducing valve, changed from liquid to gas, and then enters the stove for combustion. 3.2.2 Boil water in a soldering iron pan, and the pan will not burn out. If it is not filled with water, it will burn out quickly if it is put on the fire. This is because at standard atmospheric pressure 1, the boiling point of water is 100℃ and the melting point of tin is 232℃. When boiled with water, as long as the water is not dry, the temperature of the pot will not obviously exceed 100℃, and it will not reach the melting points of tin and iron, so the pot will not burn out. If water is not put on the fire, the temperature of the pot will reach the melting point of tin in a short time, the solder will melt and the pot will burn out. 3.2.3 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). 3.2.4 Cook food in casserole. When the food is cooked, let the casserole leave the stove and the food will continue to cook in the pot for a while. This is because when the casserole is out of the oven, the temperature at the bottom of the casserole is higher than 100℃, while the food in the pot is 100℃. After leaving the furnace, the food in the pot can absorb heat from the bottom of the pot and continue to boil until the bottom temperature drops to 100℃. 3.2.5 Cooking food in a pressure cooker is faster. It is mainly to increase the air pressure in the pot and raise the boiling point of water, that is, to raise the temperature of cooking food. 3.2.6 A lot of "sweating" on the water pipe wall in summer is often a sign of rain. The "sweating" of water pipes is not the water leakage in the pipes, but the water pipes are mostly buried underground and the water temperature is low. When the water vapor in the air contacts the water pipe, it will release heat, liquefy into small water droplets and attach to the outer wall. If there is a lot of "sweating" on the pipe wall, it means that the water vapor content in the air is high and the humidity is high, which is a precursor to rain. 3.2.7 Cooking food does not mean that the fire burns faster. 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. 3.2.8 In winter, after the water in the kettle is boiled, "white gas" can only be seen at a certain distance from the spout, but not near the spout. This is because the temperature near the spout is high, and the water vapor from the spout cannot be liquefied, but the temperature at a certain distance from the spout is low; The water vapor ejected from the spout gives off heat and liquefies into small water droplets, that is, "white gas". 3.2.9 When frying food, splashing water droplets will hear the sound of "beep, beep" and spill oil. This is because the boiling point of water is lower than that of oil and the density of water is higher than that of oil. The water droplets splashed in the oil sink to the bottom of the oil and quickly heat up and boil, and the bubbles generated rise to the oil surface and make a noise. 3.2. 10 When the temperature in the pot is high, sprinkling some water in the pot will make a "cheep, cheep" sound and release a lot of "white gas". This is because water evaporates quickly, then liquefies and makes a "cheep, cheep" sound. 3.2. 1 1 When the soup boils and overflows the pot, quickly add cold water to the pot or scoop up the soup, which can reduce the temperature of the soup to below the boiling point. Add cold water. The temperature of cold water is lower than that of boiled soup. After mixing, cold water absorbs heat and soup releases heat. In the process of raising soup, because the air is lower than the temperature of soup, the soup releases heat and the temperature drops. After pouring into the pot, it absorbs heat from the boiling soup, reducing the temperature of the soup in the pot. 3.3 phenomena related to molecular thermal motion in thermodynamics 3.3. 1 Pickled vegetables often take half a month to become salty, while only a few minutes are needed to add salt when cooking. This is because the higher the temperature, the faster the ion movement of salt. 3.3.2 If you scrape a thin layer from the wall in the corner where coal has been piled for a long time, you can see that it is black inside. This is because molecules move irregularly endlessly. In the corner where coal molecules have diffused into the wall for a long time, you can still see that it is black when you scrape off a layer. In daily life and production, we can improve our ability to observe, analyze and solve physical problems by carefully observing the physical phenomena around us and connecting with the physical knowledge we have learned. As a hot subject, physics has numerous applications in life, and the application of physical knowledge in the kitchen is really the tip of the iceberg. We must study harder, accumulate physical knowledge, improve our scientific and technological level and make our life better.