What role does physics play in life?

When the quartz clock hanging on the wall stops moving when the battery is exhausted, its second hand often stops at the position of "9" on the dial. This is because the second hand in the "9" position is most hindered by the large torque.

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 shooting a TV picture, turn off the camera flash and indoor lighting to get a clearer picture, because the reflected light of the flash and lighting on the TV screen will interfere with the transmitted light of the TV picture.

4. 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 distortion. Twisted mirror, the farther away from the mirror, the more the reflected light on the silver-plated surface deviates from the normal position according to the principle of light amplification, the more twisted the mirror will be.

5. 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. It can be seen that the route of balloon movement is tortuous and changeable. There are two reasons: first, the inflated balloon is uneven in thickness and tension, which makes the balloon contract unevenly everywhere, vacillate when deflated, and 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.

6. Sometimes after pouring a large cup of boiling water from the thermos, the bottle stopper will jump up because the cold air outside takes the opportunity to get into the thermos. After the bottle stopper is cooled, cold air is enclosed in the bottle, and heat transfer occurs with hot water. When the temperature of cold air rises and the gas expands when heated, the bottle stopper is thrown out of the bottle mouth. At this time, just gently plug the cork, then shake the thermos bottle a few times to let the boiling water evaporate a lot of water vapor, and then press the cork tightly.

7. There is an air layer in the middle of the double glass, but the air is not easy to transfer heat, which can play the role of thermal insulation, so classrooms are generally equipped with double glass windows.

8. Oily vegetable soup is not easy to cool, because the oil layer covers the soup surface, which hinders the evaporation of water.

9. There is a cooling pot in the south, which cools quickly after releasing water in summer, generally slightly lower than the temperature. This is because this kind of cooling kettle is made of clay, water can seep out, and the water that seeps into the outer wall of the container will evaporate quickly. When the water evaporates, it will absorb a lot of heat from the container and the water inside, so that the water temperature will drop to the same level as the outside of the container, and the water will also seep and evaporate, absorbing heat from the water.

10, most people think that the heat transfer speed of water in a thermos bottle is four times that of steam (or air). The thermos bottle is not full, and there is a short distance between the water surface and the cork. Then the heat dissipation speed will be much slower and its heat preservation effect will be better. When filling, I thought it was the best insulation effect, but it was not. When filled with water, it is 100℃.

1 1. The person reflected in the flat mirror is the opposite. You can try the words in the newspaper on the mirror, and you will find that the words in the mirror are reversed. A flat mirror reflects light twice, so you can see exactly the same person from two flat mirrors that intersect at 90 degrees.

12, looking at the Yuan Ye outside the window on the train, from the parallax analysis, the distant objects move slowly relative to the observer, while the nearby objects move faster, and the distant scenery rotates in the direction of the train.

13. In order to reduce the risk of forward rollover, when the motorcycle jumps over the obstacle, the rear wheel should land first.

14. The order of the nine planets in the solar system from inside to outside is: Mercury, Venus, Earth, Mars, Saturn, Jupiter, Uranus, Neptune and Pluto.

15. One of the difficulties in the inspection of the Treaty on the Limitation of Strategic Arms is that it is not easy to distinguish between underground atomic bomb tests and natural earthquakes, which is wrong. There are two kinds of waves in the world-shear wave and longitudinal wave. When the rock mass suddenly breaks and produces shear, an earthquake occurs. The fracture reduces the shear force, and at the same time, the rock and ore body vibrates briefly, which makes waves. On the other hand, earthquakes can send out all kinds of waves. On the other hand, the explosion only emits a longitudinal wave.

In A.D. 16 and 1827, British scientist Brown discovered Brownian motion, which became strong evidence of molecular motion theory. Brownian motion is the continuous disorderly motion of fine particles suspended in liquid.

17, light year is a unit of time, indicating the distance traveled by light in one year.

18, when watching a movie, you can see the picture on the screen from all angles because the screen diffuses light.

19. The oven uses infrared rays to cook.

20. Because the object expands with heat and contracts with cold, there should be a gap at the track joint.

2 1. Red light is used to represent danger signals because of its long wavelength, easy diffraction and strong penetration.

22. Soap bubbles are colored in the sun, waterfalls are rainbows in the sun, and the colored stripes seen when observing fluorescent lamps through slits belong to light interference, dispersion and diffraction respectively.

23. Sometimes, when tap water is discharged from a nearby faucet, it occasionally makes bursts of noise. It is because the frequency of water rushed out of the faucet is the same as (or very close to) the natural frequency of the water pipe, which leads to the vibration of the water pipe.

24. When shooting a TV picture, don't turn on the camera flash and indoor lighting, because the reflected light of the flash and lighting on the TV screen will interfere with the transmitted light of the TV picture.

25. When there is cold water in the pot, 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 roughly the same. As long as the water in the pot is not boiled, the water droplets will not boil, and the water droplets will gradually dry up when they evaporate on the flame.

26. There are several small holes communicating with the outside world on the side of the gas nozzle of the natural gas furnace, but why is natural gas not ejected from the side hole, but only from the nozzle? This is because the gas velocity at the nozzle is high. According to the principle of fluid mechanics, the gas velocity is high and the pressure is low, and the surface pressure of the gas flow is less than the atmospheric pressure outside the side hole, so the natural gas will not be ejected from the side hole of the nozzle.

27. People often hear such a saying in their lives: When getting an electric shock, people are attracted by it and can't pull it out. Are people really attracted by electricity? Actually, this statement is wrong. When the hand gets an electric shock, the hand will go from spasm to paralysis due to the stimulation of current. If it is on the same side of the palm or finger palm, the hand bends due to conditioned reflex when it just gets an electric shock, and the bending direction just makes the hand unconsciously hold the wire. This prolonged the electric shock time, and the hand quickly twitched and paralyzed. At this time, even if you think that you should loosen your fingers and retract your arms, it is impossible. It looks like being ".

28. People who can swing can swing higher and higher without the help of others, while those who can't swing can never swing. Correct swing action: when a person swings down from a height, his body changes from upright to squat, and when he swings up from the lowest point, his body changes from squat to upright. Because when he squatted down to the station, his center of gravity rose, which invisibly did work for himself and increased the potential energy of his center of gravity.

19 12 autumn, the ocean-going ship "Olympic" sailed in the rough sea. Coincidentally, on the sea about 100 meters away from the "Olympic", there is a much smaller armored cruiser "Hawke", which runs almost parallel to it at high speed. Suddenly, at this critical juncture, no matter how the helmsman manipulated it, it was useless. The sailors on the Hawk were helpless and watched helplessly as it hit a big hole on the Olympic side. The unexpected trouble at sea is a phenomenon of Bernoulli's principle. Fluid has the following properties: when the flow velocity is fast, the pressure on the side is small; When the flow rate is slow, the lateral pressure is high. When two ships sail side by side, the water channel between the two ships is narrow, and the water flow speed is faster than the outside of the two ships, so the pressure on the inside of the two ships is smaller than that on the outside of the two ships. Great external pressure will push the two ships aside like a pair of invisible big hands, resulting in the phenomenon that the two ships attract each other. Hulk is small and light, so he runs faster.

30. The same two wires are tied to the upper and lower ends of a heavy ball. Today, lift the ball with one thread and pull the other thread down with your hands. If you pull it down, the lower line will break and the ball will not move. If you pull the wire slowly, the wire on it will break, because "jerk" means strong force and short action time. When you pull down the wire below, the force will exceed. In this way, the line under the ball is broken. Moreover, because the action time of the force is very short and the mass of the ball is very large, the downward displacement of the heavy ball is very small in a very short time. In this way, the tension of the upper line has not changed significantly, that is, the lower line has been broken before the tension has increased significantly. If you slowly pull off the line and the force increases slowly, you can think that the force is balanced at every moment. The tension in the next row is equal to. The tension of the line above the ball is equal to the tension that increases the gravity of the ball. Obviously, in the process of slowly applying tension, the tension of the line above the ball first exceeds its tolerance, so the line above the ball breaks first.

3 1. In winter, dirty snow is darker, absorbs more light and heat, and melts faster than clean snow.

32. Hang a small iron drum on the spring scale and fill it with some water, not too full. At this time, the spring scale points to a certain scale. If you insert your finger into the water and it doesn't touch the bottom of the bucket, the pointer of the spring scale will increase. This is because the hand has a buoyancy response to water. Downward, its value is equal to the weight of water displaced by your fingers.

33. Optical cables can use the principle of total reflection to spread information efficiently.

34. The fuse is connected in series in the circuit. When the current exceeds a certain value, the fuse heats up at a temperature higher than its melting point and automatically fuses, cutting off the power supply, thus protecting electrical appliances and circuits.

35. In order to guide the generated static electricity to the underground in time and prevent the explosion caused by static electricity accumulation, a chain is often dragged on the tanker.

When two ships are running side by side at high speed, collisions often occur because of the high water velocity and low pressure between them.

37. When showing slides, in order to get a larger upright image on the screen, the distance between the slide projector and the screen should be adjusted farther, the distance between the slide and the lens should be adjusted closer, and the slide should be inserted backwards.

In the absence of other light sources, the red light from the stage spotlight shines on the actors wearing white shirts and green skirts. Excuse me, in the eyes of the audience, the color of the actor's clothing is red and black, and the visual color of the object is determined by the reflected color light. A white object reflects all colors of light, so it is white. The green skirt in the title should reflect green and absorb other colors, so the red light is absorbed and no color light is reflected to our eyes, so.

39. Due to the different positions of the sun and the moon, the gravitational superposition of tides is different, and there are both large tides and small tides.

40. The rearview mirror outside the driver's cab is not a flat mirror or a concave mirror, but a convex mirror. It makes use of the divergent effect of convex mirror on light and the characteristics of upright, narrow and virtual image, so that the objects it sees are smaller and the observation range is wider, thus ensuring driving safety.

4 1, listening to the sound I played from the tape recorder sounds strange, because the sound I heard is a combination of bone conduction and air conduction.

42. Because sound travels faster in a solid than in a gas or liquid, Shen Kuo of ancient China mentioned in his written talk about Meng Xi that soldiers sleeping with cowhide drums at night can detect invading enemies early.

43. There are many water droplets suspended in the air after the rain, and the sunlight scatters on them, showing seven different colors of white light. Therefore, beautiful rainbows always appear when the rain clears.

44. In winter, when doctors check their teeth, they often put the small mirror on the alcohol lamp and bake it before putting it in their mouth. The main purpose of this is that the mirror will not produce water mist, and they can see the teeth clearly.

45. When climbing a mountain, your upper body leans forward slightly. If a heavy object is placed at the bottom of the backpack, the line of action of gravity often passes behind the heel of the human body. In this way, when climbing a mountain, there will always be an invisible person who pulls us backwards, causing a moment of turning back. On the other hand, if the weight is placed on the top of the backpack, the line of action of gravity is within the heel range, so walking is smooth and comfortable. In addition, try to stick your backpack behind your back.

46. The sound waves emitted by the two speakers interfere with each other, forming a reinforced area and a weakened area. Therefore, when walking on campus, we often find that the sound of the broadcast becomes smaller after a few steps, and becomes larger after a few steps.

47. The temperature of hot oil is higher than the boiling point of water (100℃). When water drops are in oil, the density of water is higher than that of oil. When it sinks into the oil and boils rapidly, the hot oil will splash and break. Oil drops into boiling water, the density of oil is lower than that of water, and it floats on the water surface, so there will be no violent vaporization.

48. From February 2nd 1942 15: 02, the famous physicist Eric Fermi ignited the world's first atomic reactor, which opened the door to the atomic world for mankind. So far, the development of nuclear technology has gradually turned to the peaceful use of nuclear energy. It can be said that the use of nuclear technology has penetrated into our lives. Nuclear technology can be used to treat tumors with high-energy rays.

49. You can distinguish raw eggs from cooked eggs by spinning them. Raw eggs soon stop because the white and yolk of cooked eggs solidify into solids. When rotating, all parts of the egg can rotate together, while the egg white and yolk in raw eggs are liquids. When the eggshell rotates, the egg white and yolk will hinder the rotation of the eggshell due to inertia.

50. During artificial rainfall, planes spray dry ice (solid carbon dioxide) into the clouds to make them rain. In this process, the sublimation of dry ice reduces the temperature of the surrounding air, which makes water vapor liquefy into small water droplets or condense into small ice crystals, and falls to the ground to form rain.

5 1. Even if there is no wind, the falling route of tissue paper is tortuous and changeable. This is because different parts of the paper are convex and concave, and their shapes are different, so the air speed on the surface of the paper is different during the falling process. According to the principle of fluid mechanics, large aerodynamic force and small pressure lead to uneven aerodynamic force on the paper, which changes with the movement of the paper, so the paper keeps rolling and falling zigzag.

52. When the spin-drying bucket of the washing machine rotates at normal high speed, the rotation is often very smooth. However, when the spin-drying bucket is gradually reduced, the washing machine often shakes violently for a period of time before stopping. This is because the spin-drying barrel of the washing machine will give the machine a periodic motive force when it rotates. When it rotates at high speed, the frequency of this motive force is much higher than the natural frequency of the washing machine body, so the vibration of the machine body is slight; When the rotating speed of the spin-drying barrel is gradually reduced, the frequency of the driving force on the machine body is gradually reduced. When it stops, the frequency of the driving force is close to and equal to the natural frequency of the body. At this time, the body vibrates, so it shakes particularly badly.

53. Walking on the mountain road at night, holding a flashlight is better than wearing headlights. This is because the light of the headlight comes from the position close to the eyes, so the eyes can't see the shadow area that the light can't illuminate. Therefore, the eyes are "bright in the future", and they don't notice stones or pits, and the position where the flashlight emits light is much lower than that of the eyes, so the eyes can see the shadow areas that the light can't shine on, so the stones on the ground drag long shadows, and the low places look like.

54. We all blow soap bubbles, which first float and then fall. This is because at the beginning, the soap bubbles are full of hot air blown from the mouth, and the soap film separates them from the outside, forming two areas, and the temperature of the internal hot air is higher than that of the external air. At this time, the density of the gas in the soap bubble is lower than that of the outside air. According to Archimedes principle, the buoyancy of soap bubbles at this time is greater than the gravity it receives. So, it will rise. This process is similar to a hot air balloon. With the beginning of the rising process and the passage of time, the gas inside and outside the soap bubble exchanges heat, and the temperature of the internal gas drops. Because of thermal expansion and contraction, the volume of soap bubbles gradually decreases, and the buoyancy of the external air it receives will gradually decrease, while the gravity it receives remains unchanged. In this way, when gravity is greater than buoyancy, soap bubbles will fall.

Suppose that during a trip, you want the average speed to be 40 miles per hour, and when you are halfway there, the average speed is only 20 miles per hour. In the remaining half of the journey, your speed should be faster than light, so that the average speed can reach 40 miles per hour. This is because when you reach the midpoint, you have no time. The key to dealing with the "thorny" problem of speed and distance is often time. 58. A cubic foot of seawater weighs about 64 pounds. Suppose you pour a cubic foot of seawater into a plastic bag, tie the mouth of the bag tightly so that there are no bubbles in it, and then tie a rope to the world bag and put it into the ocean. When all the water bags are in the water, you can pull the rope effortlessly. Because if you completely immerse a water bag in water, it will neither sink nor float, but it will stand still. This bag can be of any shape. The weight of the water in the bag is just equal to the buoyancy of the surrounding water, which just supports it.

56. For a cup of coffee, in order to make it hotter after a few minutes, you should add milk immediately. The higher the temperature around the object, the faster the cooling rate will be (Newton's cooling law: the cooling rate is proportional to the temperature difference), so adding milk immediately can slow down the cooling rate of you and the coffee before. If you wait, the very hot coffee will soon cool down, and when you add milk, the temperature will drop. You will change the coffee from black with fast heat dissipation to milky brown with slow heat dissipation, so adding milk immediately can also reduce the radiant heat. Moreover, if you add milk, the total amount of liquid will expand, while the heat dissipation surface area of liquid will remain the same, which will also lead to a decrease in cooling rate. Therefore, it is better to add milk immediately!

On a sunny day, you see your shadow is blue in the snow. The part directly illuminated by the sun shows the colors of the sun: yellow and white. The snow in your shadow is not directly illuminated by the sun, but by the light of the blue sky. So the shadows are mostly blue.

58. Parallel plate capacitors have a certain charge, and then discharge to produce sparks. If the parallel plates are charged exactly the same as last time, but now the distance between the two plates is wider. If they are short-circuited again, the spark will be bigger than the first spark (it will release more energy). What energy will make the spark bigger? This energy comes from the work done when the positively charged and negatively charged plates are pulled apart. This work does not increase the charge on the two plates, but is converted into the energy of the electric field between the two plates, which increases the voltage between the two plates.

59. The blue star Alpha Lyra is hotter than the red star Alpha Scorpio, because when a solid is heated, it will start to glow when the temperature is high enough. It will glow red at first, and when the temperature continues to rise, it will turn orange, yellow and white in turn. If the temperature is high, it will turn blue. The light-emitting color of high-pressure gas changes with temperature in the same way as that of melted solids, so the neon lights in the red neon lights on the street are actually as hot as Scorpio.

If you want to see a magnified image in the mirror, you should use concave mirror.

6 1, under the swimming pool, look up at the water surface, which reflects light like mercury.

62. The colors on the color TV screen are composed of red, green and three lights.

There is a boat floating on the lake. There are many stones in the boat. Now take out the stone and throw it into the water, and the water level of the lake will drop.

The bucket contains water and a lot of ice, and the ice touches the bottom of the bucket. After the ice melts, the liquid level in the bucket is higher than the original liquid level.

In a closed room, the correct way to reduce the average indoor temperature with a working refrigerator is to unplug the power supply and open the refrigerator door.

66. Take a spoonful of seawater. Like tap water, seawater is colorless and transparent, but the sea looks blue. This is because when the sun shines on the sea, long-wavelength light such as red light and orange light can bypass all obstacles and go forward bravely. However, light with short wavelength, such as blue light and purple light, will mostly scatter around or simply reflect back when it is blocked by seawater. What we see is.

Dirac is the founder of quantum radiation theory. Thomas Young first put forward the word "interference", Copernicus founded the theory of celestial bodies, michael faraday published the experimental study of electricity, Rutherford put forward the nuclear model of atoms, and Oster discovered the current magnetic effect.

Due to the low air pressure in mountainous areas, the average temperature in mountainous areas is lower than sea level.

Two substances with the same number of protons in the nucleus are called isotopes.

The atmospheric ozone layer is called the "protective umbrella of the earth" because it can absorb the ultraviolet rays in the sun.

7 1. After it snows in winter, sprinkle salt on the road to melt snow, because the melting point of salt and ice decreases after mixing.

72. Theoretically, a water pump can pump water to the depth of10m underground, because the atmospheric pressure can only lift the water to10m.

Fried dough sticks are fluffy and delicious than oil cakes because of their different shapes. Fried dough sticks are made of two noodles stuck together. After oiling, the stuck part will not be fried hard, and there is a chance of expansion. The outer surface of the oil cake is fried hard and cannot fully expand.

Put your hand in hot air at 100℃ and it won't burn, because the evaporation of sweat can lower the skin temperature.

75. Water drops on two iron plates. The warm iron plate evaporates faster than the hot iron plate, because the hot iron plate will form a steam layer around the water drops, which will slow down the evaporation of water drops.

76. Dig a small hole in a closed light-tight box. Black velvet and ink drops look darkest in the moonlight, because the light has been reflected inside the box after entering the small hole, and there is little chance of re-shooting.

There is a layer of material called "ablation layer" on the surface of the return capsule of Shenzhou VI spacecraft launched by China, which can absorb a lot of heat during gasification and protect the return capsule from being burned by high temperature when it returns to the atmosphere.

78. On a clear summer night, when we look up at the starry sky, we will find that the stars are constantly flashing. Excuse me, this is because the atmospheric density distribution is unstable, which makes the refracted light of starlight passing through the atmosphere change with the atmospheric density from time to time.

79. On a hot summer day, when you were walking on the hot asphalt road, a sprinkler just came to sprinkle water on the ground. At this time, you feel even more sultry. Excuse me, this is because the water has evaporated, which has brought the underground heat to people.

80, 1999, NATO troops led by the United States used a graphite bomb when they brutally bombed the power plants in Yugoslavia. After the explosion, a large number of graphite fibers were released, causing short circuit of the equipment.

8 1. When fireworks are set off in festivals, fireworks bombs explode in the air, forming colorful fireworks. During the falling process after blasting, the fireworks were spherical, and the radius gradually increased around the explosion point. At the moment of explosion, the explosive force is much greater than gravity, which can be considered as a momentum conservation process. All the fragments of fireworks have the same speed, and because each fragment is subjected to the same gravitational acceleration, the fragments can remain spherical when they explode.

Huygens, a physicist in 82,17th century, put forward the wave theory of light. In his theory, he put forward a concept that had an important influence on the development of optical theory later: secondary wave source.

The lightning rod was invented by Benjamin, a famous physicist? American Franklin.

In 1984, 1895, roentgen first discovered X-rays.

The three major discoveries of natural science in the 85th and19th centuries are the theory of energy transformation and conservation, the theory of cells and the theory of evolution.

86. The basic property of an electric field is to exert a strong effect on the charge put into it.

A wire is wound around a coil on an iron block. As long as there is current flowing through the wire, the iron block will become a magnet.

88. Two identical glass bottles, one containing sand and the other containing water, slipped down the same slope and reached the bottom. The one containing sand rolled quickly. Because water can flow in a bottle, it will lose mechanical energy due to friction, while the one filled with sand is difficult to move in the bottle without friction, and the mechanical energy loss is minimal. From the perspective of energy conservation, it should be that a bottle full of sand rolls fast.

89. Look at a mirror and a piece of gray paper with a flashlight at the same time, and observe that the gray paper is bright. This is because the paper produces diffuse reflection, and some reflected light can be seen from all directions; But the mirror is specular reflection, and the reflected light can only be seen at a certain angle, and there is no reflected light in other directions.

A spaceship flies around the earth outside the atmosphere after turning off the engine. The water droplets in the spaceship are spherical.