We have all memorized a lot of knowledge points during our long study career, so we must be very familiar with them! Knowledge points can also be commonly understood as important content. Want a copy of the organized knowledge points? The following is my organized knowledge of physics in life, just for reference, I hope it can help you.
Physical knowledge of life 1I. Phenomena related to knowledge of mechanics
1, the electric kettle spout and pot belly constitute a connector, the water surface is always flat.
2, the thin blade of the kitchen knife is to reduce the force area and increase the pressure.
3, the blade of the kitchen knife has oil, in order to cut vegetables, so that the contact surface is smooth, reducing friction.
4, kitchen knife handles, spatula handles, kettle handles have convex and concave patterns, so that the contact surface is rough, increasing friction.
5, the fire shovel to send coal, is to use the inertia of the coal into the fireplace.
6. Pour boiling water into a thermos and know the amount of water according to the sound. As the amount of water increases, the length of the air column decreases, the vibration frequency increases, and the pitch rises.
7, grinding kitchen knives should be constantly pouring water, because the kitchen knife and stone friction work to generate heat so that the internal energy of the knife increases, the temperature rises, the hardness of the knife becomes smaller, the knife is not conducive to; pouring water is the use of heat transfer to make the knife to reduce the internal energy, the temperature decreases, will not rise to too high.
Second, the phenomenon related to knowledge of electricity
1, electric rice burger cooking, electric frying pan cooking, electric kettle boiling water is the use of electrical energy into internal energy, are the use of heat transfer cooking, cooking, boiling water.
2, exhaust fan (range hood) use of electrical energy into mechanical energy, the use of air convection for air transformation.
3, rice cooker, electric frying pan, electric kettle three-pronged plug, inserted into a three-hole socket to prevent electrical appliances leakage and electrocution accidents.
4, the microwave oven heating evenly, high thermal efficiency, health and pollution-free. The heating principle is to use electrical energy into electromagnetic energy, and then electromagnetic energy into internal energy.
5, the kitchen lights, the use of the thermal effect of the current work, the conversion of electrical energy into internal energy and light energy.
6. Kitchen stoves (honeycomb, liquefied petroleum gas, coal, and wood stoves) convert chemical energy into internal energy, i.e., the fuel is burned to release heat.
Physical knowledge of life 2We in daily life, production, as long as careful observation of the physical phenomena around us, linked to the physical knowledge we have learned to analyze and explain these phenomena, we will be able to improve the observation, analysis and problem-solving skills. The first step in the process is to make sure that you have a good understanding of how to use the software to help you with your research and development!
First, the use of knowledge of mechanics in life
windy, in order to prevent drying on the wire clothes stacked or fall down, you can first use a plastic rope knot a ring set, and then the rope ring set in the wire, and then hang the hanger in the ring set, so that the hanger will not easily slide. The purpose of doing this is to increase the force area between the rope loop sleeve and the wire to increase the resistance.
Sharpening kitchen knives should be constantly pouring water, because the kitchen knife and stone friction work to generate heat so that the internal energy of the knife increases, the temperature rises, the hardness of the knife becomes smaller, the knife is not conducive to the mouth. Watering is the use of heat transfer so that the internal energy of the knife is reduced, the temperature is lowered, and will not rise to too high.
Second, the use of thermal knowledge in life
When boiling water, in order to save time and electricity, you can first add a little hot water. The purpose of this is to speed up molecular motion and make molecular diffusion faster.
When frying lean meat, if the meat directly into the hot frying pan stir-fry, the water contained in the lean meat fibers to evaporate sharply, resulting in the meat becomes dry and hard. In order to stir-fry the meat is delicious, the masters often pre-mixed into the right amount of starch, to be put into the hot frying pan, attached to the meat outside the starch paste in the water evaporation, and the water in the meat is difficult to evaporate, but still maintains the meat of the tenderness.
Third, the use of acoustic knowledge in life
Nowadays, residential buildings are generally equipped with security nets, the top of the net there is a very large thin sheet of iron made of rain shield, so that the things inside the security nets will not get wet. However, whenever it rains, the rain hit the rain shield, issued a very loud pitter-patter, in the night, the noise is even more affecting people's sleep, if you put a piece of sponge on the iron sheet, then the noise can be reduced.
When we go to the store to buy bowls, porcelain, we use our hands or other objects to tap the porcelain, through the sound will be able to judge the porcelain is good or bad.
Fourth, the use of optical knowledge in life
In the hot sun to wash the car, the water droplets formed by the convex lens effect will make the top layer of the car paint to produce localized high temperature phenomenon. The paint will lose its luster after a long time. If you wax at this time, it is also easy to cause uneven body color. Generally wash the car in the evening or in the shade.
Take a picture of the TV screen, you should turn off the camera flash and indoor lighting, so that the picture is clearer. This is because the reflected light from the flash and lights on the TV screen interferes with the transmitted light from the TV screen.
Fifth, the use of electrical knowledge in life
Make full use of the residual heat of the rice cooker. Cooking, when the pot boils, the key will be lifted that cuts off the power supply, the use of the residual heat of the hot plate, to be a few minutes and then press the key, rice cooked rice cooker will automatically disconnect the power supply.
Household appliances should not be in standby mode, if the household appliances in standby mode, both power consumption and injury to the machine. Watching TV, the volume and brightness as low as possible, which can also save electricity, and the eyes are not easy to fatigue. After the shutdown due to the remote receiving part is still charged, and the indicator light, will consume part of the power, so after the shutdown should be unplugged.
In short, in life, as long as we carefully observe the physical phenomena around us, brainstorming, will let the physical knowledge to serve us fully.
Physical knowledge of life 3The phenomenon of charged objects lose charge is called discharge. Common discharge phenomenon has the following kinds:
1 grounded discharge
The Earth is a good conductor, because it is particularly large, so it can accept a large number of charges without significantly changing the Earth's potential, which is as pumping water from the ocean or discharging water to the ocean, and can not significantly change the height of the sea level. If a charged conductor is connected to the earth by a wire, the charge will flow from the charged body to the earth until the conductor is so poorly charged that it can be considered to be no longer charged. (If the conductor is positively charged, free electrons actually flow from the earth to the conductor. This is equivalent to the flow of positive charge from the conductor to the earth.)
It is often necessary to avoid the accumulation of electric charges in production and in practice, and grounding is an effective measure.
2 tip discharge
Normally air is not conductive, but if the electric field is particularly strong, the positive and negative charges in the air molecules are subject to a strong electric field force in the opposite direction, it is possible to be torn apart, a phenomenon known as air ionization. Because of the ionization of the air can move freely after the charge, the air can conduct electricity. The negative charge generated by the ionization of air is the electron, and the atom that loses the electron is positively charged and is called a positive ion.
As the same kind of charge mutual exclusion, the electrostatic charge on the conductor is always distributed on the surface, and generally speaking, the distribution is uneven (Figure 2), the tip of the conductor is particularly dense charge, so the tip of the air near the electric field is particularly strong, so that the air residual small amount of ions accelerated movement. These high-speed ions hit the air molecules
and ionize more molecules. At this point the air becomes a conductor and a tip discharge occurs.
Tip discharge is technically important. High-voltage transmission lines and high-voltage equipment, metal components, the surface should be very smooth, in order to avoid the loss of power due to tip discharge or cause accidents.
3 spark discharge
When the high-voltage charged body and conductor close to the conductor, a strong electric field will make the air between them instantly ionized, the charge through the ionized air to form a current. Because the current is particularly large, generating a lot of heat, making the air sound and light, resulting in electric sparks. This discharge phenomenon is called spark discharge.
Spark discharge is often encountered in life. In the dry winter, wearing sweaters and chemical fiber clothes, after a long walk, due to friction, the body will accumulate static charge. At this time, if your fingers are close to metal objects, you will feel a pinprick of pain on your hands. This is caused by spark discharge. The pain can be avoided if you take a key beforehand and place the tip of the key near another metal object. Try it in a dimly lit place, when the tip of the key is close to a metal object, you will not only hear a ringing sound, but also see sparks.
In some factories or laboratories, the presence of large amounts of flammable gases, the staff to wear a special shoe, the conductivity of this shoe is very good, the charge can be channeled into the earth, to avoid the accumulation of electric charge on the body, in order to avoid sparks discharge, causing fires.
Physics in Life 41. Why is the sky red in the morning and evening?
In the morning and evening, before and after sunrise and sunset in the sky, often appear colorful colorful clouds. Both the morning and evening sunsets are due to the scattering of light by the air. When sunlight enters the atmosphere, it is scattered by atmospheric molecules and particles suspended in the atmosphere. These atmospheric molecules and particles do not emit light by themselves, but because they scatter sunlight, each atmospheric molecule forms a source of scattered light. The shorter wavelengths of the sun's spectrum, such as violet, blue, and cyan, are most easily scattered, while the longer wavelengths of red, orange, and yellow are highly transmissive. After these rays are scattered by air molecules and impurities such as water vapor, the sky there takes on brilliant colors.
2. Why are rainbows formed? Why are rainbows arch-shaped?
(1) A rainbow is caused by the emission and refraction of sunlight into water droplets in the air.
(2) When the conditions of the atmosphere are such that a rainbow is formed, the rainbow is actually a circular shape. But due to the obstruction of the horizon, we can only see at most half of the circle. Also, since atmospheric conditions are different everywhere, in most cases we can see only a small arc of the circle. At sea, where there is little obstruction and the atmospheric conditions are relatively uniform over a wide area, it is often possible to see the full half-circle of a rainbow.
3. What is it about snow that makes it cold?
Snow and snow is a process of solidification and melting; solidification is an exothermic process, so naturally it is not cold, while melting is a heat-absorbing process; so snow is not cold and snow is cold.
4. Real gold is not afraid of the fire to refine
From the melting point of gold, although not the highest, but there are 1068 ℃, and the general temperature of the flame is about 800 ℃, due to the temperature of the flame is less than the melting point of gold, so the gold can not be melted.
5. Boiling water does not ring, ringing water does not open
Before the water boils, due to convection, the water bubbles rise while vibrating up and down, most of the bubbles rupture under pressure within the water, its rupture sound and vibration sound with the container to produce **** sound, so the sound is great. After the water boils, the upper and lower isothermal, bubble volume increases, under the action of buoyancy has risen to the surface of the water before rupture, so the sound is relatively small.
6. Water and fire are incompatible
Material combustion, must reach the ignition point, due to the specific heat of water, water and fire contact can be a large amount of absorbed heat, to make the temperature of the object on fire decreased; at the same time after vaporization of water vapor surrounded by burning objects outside, so that the object is impossible to contact with the air, and without the air, the combustion can not be carried out.
7. Sit on the ground and travel 80,000 miles
As the Earth's radius of 6370 kilometers, the Earth per revolution, the surface of the object "walk" of the distance of about 40003.6 kilometers, about 80,000 miles.
8. The snow is a blessing in disguise
The snow on the ground has a lot of loose air spaces, which are filled with non-flowing air, and it is a poor conductor of heat, so when it covers the crops, it can prevent heat conduction and air convection, and thus provide insulation.
9. A drop of water can be seen in the sun
A drop of water is equivalent to a convex lens, according to the law of convex lens imaging, through a drop of water can have the image of the sun, the small in the big.
10. Next to the fire, there will be wind
The air near the fire is heated by the expansion of the rise, the distant cold air will come to fill, the flow of hot and cold air to form the wind.
11. Mercury falls to the ground, pervasive
The density of mercury is greater than the density of the substances that make up the ground, and mercury has mobility, so it is always sunk below other substances.
Physical knowledge of life 5
Sometimes we will be very surprised that a lot of things should be in accordance with the usual direction of development, but the fact is not so, a lot of common sense is in fact some physical phenomena, some time the conditions do not allow or the conditions have changed, things will not be in accordance with the common sense of the change, the following to share some interesting physical knowledge.
First, hot cold porridge or cold rice, the pot issued a "puff toot, puff toot" sound, and bubbles continue to come out, but a taste, porridge or rice is not hot, this is why?
Boiling cold porridge or rice is not the same as boiling water. Although water is a bad body of heat, the conduction of heat is very slow, but the water has a very good fluidity. When the water at the bottom of the pot is heated, it should be expanded, the density decreases on the float, around the cool water to flow over to fill, through this convection, the heat of the bottom of the pot is constantly transferring to all parts of the water and make the water hot. And cold porridge or rice, both poor mobility and not easy to conduct heat. Therefore, when the bottom of the pot of porridge or rice heat absorption, the temperature rises quickly, but can not quickly upward or around the flow, a lot of heat is concentrated in the bottom of the pot and the bottom of the pot of porridge burnt. Because it is difficult to transfer the heat to the top of the porridge, so the top of the porridge is still cool. When heating cold porridge or rice, add more water to the pot to thin the porridge and enhance its fluidity. In addition, it should be stirred diligently to force convection, so that the porridge can be evenly heated.
Second, with the casserole cooking meat or soup, when the soup boiled down from the stove, the soup will continue to boil for a period of time, while the iron, aluminum pots do not have this phenomenon, this is why?
Because the casserole is fired clay, and non-metallic specific heat is much larger than metal, heat transfer capacity is much worse than metal. When the casserole is heated on the stove, the temperature of the outer layer of the pot is considerably more than 100 ℃, and the inner layer is slightly higher than 100 ℃. At this point, the pot absorbs a lot of heat and stores a lot of thermal energy. Casserole from the stove down, much higher than 100 ℃ pot of the outer layer of the pot will continue to transfer heat to the inner layer, so that the pot of soup still reach 100 ℃ and can continue to boil for a period of time, iron, aluminum pots do not appear this phenomenon (the reason for this please students to analyze their own).
Third, fried meat in the "meet cooked". On New Year's Day, people always have to fry a few meat dishes, then how to stir fry meat?
If the meat directly into the hot frying pan to stir-fry, the water contained in the lean meat fibers to evaporate sharply, resulting in the meat becomes dry and hard, and even the meat will be fried burnt fried paste, greatly losing the taste. In order to stir-fry the meat is delicious, the masters often pre-mixed into the appropriate amount of starch, then the meat into the hot frying pan, attached to the starch paste outside the water evaporation, and the water in the meat is difficult to evaporate, but still maintains the original meat tenderness, but also reduces the loss of nutrients, and meat and cooked quickly that "meet cooked". With this method of fried meat, both tender and flavorful, but also nutritious.
Fourth, what is the best way to thaw frozen meat? From the refrigerator out of frozen meat, frozen chicken, how to thaw it?
Use cold water close to 0 ℃ is best. Because the temperature of frozen meat is below 0 ℃, if placed in hot water to thaw, frozen meat from the hot water to absorb heat, the outer layer of its rapid thawing and make the temperature rise to 0 ℃ or more, this layer of meat between the gap between the transfer of heat, the ability to decline, so that the internal frozen meat is not easy to heat thawing and the formation of hard core. If the frozen meat in cold water, the frozen meat, frozen chicken heat absorption and make the cold water temperature quickly dropped to 0 ℃ and part of the water will also freeze. Because 1 gram of water into ice can release 80 calories (and 1 gram of water to reduce 1 ℃ only 1 calories), released so much heat is frozen meat absorption, so that the temperature of the outer layer of meat faster, and the inner layer is easy to absorb heat, so that the temperature of the whole piece of meat is also faster rise to 0 ℃. So repeated several times, frozen meat can be thawed. From the nutritional point of view analysis, this uniform and slow warming method is also scientific.
Pressure
(1) The human teeth use the knowledge of pressure. People's incisors and canines are more pointed, bicuspids, molar teeth, the crown of the teeth have pointed protrusions, these are to reduce the area of force, increase the pressure of the way to make it easier for people to bite off the food or chew the food.
(2) the size of the human foot, the general rule is that taller people's feet are also larger, so as to ensure that people with different weights walk on the ground pressure is basically the same.
(3) when people inhale, the pectoral muscles so that the volume of the chest cavity increases, the volume of a certain mass of gas in the lungs increases, the pressure decreases, less than the external atmospheric pressure, the atmospheric pressure of the air into the respiratory tract, into the alveoli in the human body; when people exhale, the pectoral muscles so that the chest cavity contraction compression of the lungs so that it decreases the volume of the gas in the lungs decreases in volume and the pressure increases, greater than the atmospheric pressure, so as to exhale the carbon dioxide.
(4) The flow of blood in the human body depends on the pressure generated by the contraction of the heart.
Friction
(1) In the human mouth, the surface of the tongue is rough, and there are also lines on the palate, which increase the friction with the food, making it easier to stir the food or send it into the esophagus.
(2) People have special palm lines on the palms of their hands and feet. In a certain grip, the fingerprints and palm prints on the palms of the hands can increase the friction with the contact object, making it easy for people to grasp what they want to hold. Patterns on the palms of the feet, can increase friction, so that people walk feet do not and socks, shoes slippery, more energy.
(3) when people walk, friction between the feet and the ground, the foot force backward stirrups, relative to the ground has a tendency to move backward, the ground to the sole of the shoes will produce an obstacle to the feet relative to the ground backward movement of friction resistance, the force forward, it is this force that makes the person forward.
Simple Mechanics
The human forearm is a laborious lever. The elbow joint is its fulcrum, and when lifting something, the gravity of the object is the resistance acting on it, and the force exerted by the biceps is its power.
Energy
(1) People eat food, after digestion, the large molecules that can not be directly absorbed by people into small molecules that can be absorbed and utilized by people through the digestive tract into the cells, the chemical changes that occur in the cells, the biomass energy is converted into chemical energy to be utilized by people.
(2) The physiological curvature of the human body (cervical, thoracic, lumbar, and sacral curvature), as well as the curvature of the arches of the feet, the femur, and the tibia, like the springs under the seat of a bicycle, can convert the kinetic energy of the up and down movement of the human walking or jumping process into elastic potential energy, and can effectively reduce the vibration impact on the brain during the walking process.
Thermal
(1) in the person longer intense activity, the human body produces a lot of heat, these heat is not timely to disseminate out, will lead to the normal physiological activities of the human body is destroyed, the human body's sweat glands will secrete sweat in a timely manner, the evaporation of the sweat to absorb a lot of human body heat, so that the human body temperature is maintained at a constant state of 37 ℃ steady state. The body temperature is maintained at a constant temperature of 37 degrees Celsius. In the case of higher temperatures, the body's heat is more difficult to distribute, the body will also sweat a lot of ways to dissipate heat.
(2) Hair can not only make you more beautiful, but also can regulate body temperature to protect the role of the brain. In winter, the cold wind, blood vessel contraction, hair can make the head to maintain a certain amount of heat; summer, the hot sun, hair can block the daylight . Direct sunlight on the scalp damage, at the same time, blood vessel expansion, hair can help to radiate heat to the outside. Therefore, the hair has both thermal insulation and heat dissipation of the dual function.
Optics
(1) The human eye, is the most sensitive "camera". The pupil of the eye is like the aperture of the camera, the intensity of the light is different, its size will change; lens is like a convex lens, and its focal length can be changed; retina is like "film". For the normal eye, when people look at objects farther away, the lens curvature decreases, the focal length becomes larger; look at objects nearer, the lens curvature becomes larger, the focal length becomes smaller, can always make the image clearly into the retina.
(2) The human body has a constant temperature, will emit a certain wavelength of infrared radiation. However, when there is inflammation somewhere in the body and the temperature increases locally, the intensity of the infrared rays emitted will change, so medical diagnosis can be aided by taking infrared photographs.
(3) The human two eyes according to the linear propagation of light to determine the specific location of the object. When a person with one eye to see the object, not only do not have two eyes to see clearly, and against the light to see the past, can not determine the object from the person's distance, but also can not determine the exact location of the object; and with two eyes together to see, against the light to see the past, the light crosses the location of the object is the location.
Electricity
The human body has a bioelectric current, and the detection of the bioelectric current of the human body with medical equipment can be used to understand whether the work of human tissue is normal. For example: medical electrocardiogram, electroencephalogram, is made according to this phenomenon. The polygraph is also based on the changes in the human body's current to make a judgment. People lie, the body's bioelectric current will be abnormal changes, according to the bioelectric current can be made to test whether the person is lying judgment.
Acoustics
(1) The human vocal cords vibrate to produce sound, allowing people to communicate with each other verbally. Different people have different vocal cords, which produce different tones in their voices, and we can recognize who is speaking by their tones.
(2) The human ear is the organ of hearing, sound through the vibration of the air into the human ear. Vibration of the air so that the eardrum vibration, the eardrum to the vibration of the auditory ossicles, through the auditory nerve to the brain, the formation of hearing.
(3) The transmission of sound requires a medium. Human bones can transmit sound, if only conductive deafness, you can use bone conduction to hear the sound.
(4) The human binaural effect helps a person determine the location of the sound source. The distance from the sound source to the two ears is generally different, the moment the sound reaches the two ears and characteristics such as intensity are also different, according to these differences, people can judge the location of the sound source.
Physics in Life 71. Why do bicycle tires have bumpy patterns?
The amount of friction is related to two factors: the amount of pressure and the roughness of the contact surface. The greater the pressure, the greater the friction; the rougher the contact surface, the greater the friction. Bicycle tires have a bumpy pattern, which increases friction by increasing the roughness between the bicycle and the ground, and is designed to prevent the bicycle from slipping.
2. Why do I need sunscreen?
The use of physics, relying on physical sunscreen agents (commonly titanium dioxide and zinc oxide) reflective effect, shielded from ultraviolet rays, to achieve the purpose of sun protection. Simply put, it utilizes reflective particles to form a protective wall on the surface of the skin, so that the skin no longer absorbs UV rays.
3. Why is the front window of the car made into a tilted glass?
From the optical point of view to analyze: the windshield is transparent, but not absolutely no reflection, sitting behind the driver's passengers will be due to reflection imaging in front of the driver. Small cars are shorter, sitting inside the passenger by the windshield imaging in front, if the windshield is vertical, the image and the car in front of the height of the pedestrian is almost the same, which will interfere with the driver's visual judgment. When the windshield is tilted, the image will be in front of the car above, will not affect the visual judgment, to ensure the safety of driving.
4. Why do incandescent lamps have to be pear-shaped?
The filament of the bulb is made of tungsten metal. The filament heats up to a temperature of more than 2500°C. The tungsten metal sublimates at high temperatures. Metal tungsten sublimation at high temperatures, part of the metal tungsten particles from the filament surface to run out, precipitation in the inner wall of the bulb. Over time, the bulb turns black, reducing brightness and affecting illumination. According to the gas convection is downward and upward movement of the characteristics of the bulb filled with a small amount of inert gas, and make the bulb pear-shaped. In this way, the inert gas convection inside the bulb, tungsten metal evaporation of most of the black particles by the gas rolled up to the top, deposited in the neck of the bulb, you can reduce the impact on the bulb around and at the bottom of the bulb, so that the bulb brightness is not affected.
5. Why should I turn off the lights in my car when I drive at night?
It depends on the brightness of the external environment. Driving during the day with or without the lights on inside the car has no effect on driving. But not at night, because for the glass, when one side is dark and one side is bright, the bright side will form a mirror. So driving at night, the interior lights, the car is very dark, the glass becomes a mirror, can not see outside the car, see is the image of the car, not conducive to driving. So to turn off the lights inside the car, in order to see the driver to see the road outside the car.