Scientific common sense in life:

1. Why does sorbet get angry?

The reason why sorbet bubbles is because there is a lot of invisible water vapor in the outside air. When it comes to cold sorbet, it will liquefy into droplets when it is cold. It seems that the sorbet is bubbling.

2. Why do sunflowers always face the sun?

Sunflower stems contain a wonderful auxin. This auxin is very afraid of light. When it is illuminated, it will go to the backlight side, and the cells on the backlight side will multiply rapidly. Therefore, the backlit side will grow faster than the bright side, which will bend the sunflower to light.

3. Why do cicadas shed their skin?

Cicada's shell (exoskeleton) is hard and can't expand with the growth of cicada. When the cicada grows to a certain stage, the cicada's exoskeleton restricts its growth, and the cicada loses its original exoskeleton, which is cicada slough.

4. How do bees make honey?

Bees spit the collected sweet flower juice into an empty beehive. At night, they suck sweet juice into their honey stomachs to make it, and then spit it out and swallow it. It takes 65,438+000 ~ 240 times to make sweet honey.

5, hanging on the wall of the quartz clock, when the battery runs out and stops, its second hand often stops at the "9" position on the dial. This is because the second hand is most hindered by the large torque at the "9" position. Scientific common sense

6. 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.

7. When taking pictures on TV, turn off the camera flash and indoor lighting to make the picture 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.

8. At the same temperature, frozen meat 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,

9. When there is cold water in the pot, the water droplets attached to the outer surface of the pot bottom can only be dried up after a long time on the flame, and will only boil when it is dried up. This is because the water droplets, the pot and the water in the pot keep heat conduction, and the temperature is almost the same. As long as the water in the pot is not boiled, the water droplets will not boil, and the water droplets will evaporate on the flame and be gradually dried up.

10, out-of-shape mirror, the farther away from the mirror, the more out of shape. 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.

2. 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.

3. Know little about 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 force 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.

4. Related knowledge of physics

=U/R

U=IR

R=U/I

P=W/T

P=UI

P=U^/R

P=I^R

Physical formula of Q=UIt physical quantity

Current definition formula I=Q/t Ohm's law I=U/R series circuit I=I 1=I2 parallel circuit I=I 1+I2.

Voltage series circuit U=U 1+U2 parallel circuit U=U 1=U2

Total resistance series r =R 1+R2 parallel r =R 1R2/(R 1+R2)

Definition of electric power P=W/t General formula P=UI

Definition of electric work W=UIt Known electric power W=Pt Known electric quantity W=UQ

Joule Law of Conductor Heat Q=I2Rt

Square of area S=a2 rectangle S=ab circle S=π(D/2)2

Volume cylinder V=Sh drainage method v solid =V2-V 1 cubic V=a3 submerged, v line =V object.

Speed definition v=s/t Average speed v=s total /t total.

Density definition ρ=m/V

Gravity G = mg

Buoyancy formula method F floating = ρ gV liquid row weighing method F floating =G-F' floating and hanging F floating =G Archimedes principle F floating = G row

Cause F float =F up -F sink down when f float = g-n.

Pressure definition formula p=F/S liquid interior p=ρgh

Power (mechanical) definition formula P=W/t Automobile power P=Fv

Work (mechanical) definition formula W=Fs total work w total =W useful +W quantity

Lever balance condition F 1l 1=F2l2

Force in the same direction F =F 1+F2 Force in the opposite direction F =F 1-F2 Pressure of objects on a horizontal table F=G Total pressure of liquid and gas F=pS.

Definition of mechanical efficiency η=W Useful /W Total lifting weight η=Gh/Fs Horizontal moving weight η=fs object /Fs

Hot fuel combustion Q=qm heat absorption and heat release q = cm δ t

Mechanical energy Mechanical energy = kinetic energy+potential energy

Q=U^/Rt

Q=I^Rt

Second grade.

Velocity V(m/S) v= S: distance /t: time gravity G (N) G=mg m: mass g:9.8N/kg or 10N/kg density ρ (kg/m3) ρ= m/v m: mass v: volume resultant force f (n) in the same direction: f. The formula f float =G object is only applicable to object float or floating buoyancy f float (n1l1= f2l2f1 Power arm F2: resistance L2: resistance arm crown block F=G object S=h F: rope free end tension G object: object gravity S: rope free end moving distance H: object lifting distance moving pulley F= (G object +G wheel 2 S=2 h G object: gravity g object wheel: moving pulley gravity pulley group F= (G object +G wheel) S=n h n: rope. W=Fs F: force s: moving distance of force useful work w =G object h total work w total =Fs mechanical efficiency η=W When the pulley block is placed vertically, 100% power P (w) P= w/t W: work t: time pressure p (Pa) P= F/s F: pressure s: stress.

5. High school physics knowledge * * *

Uncle Liu's blog

1, Galileo

(1) overthrew Aristotle's view that "force is the reason to maintain motion" through ideal experiments.

(2) Overthrow Aristotle's view that "heavy objects fall faster than light objects"

2. Kepler: put forward Kepler's three laws of planetary motion;

3. Newton

(1) put forward three laws of motion.

(2) discovering the law of universal gravitation;

4. cavendish: The gravitational constant g is accurately measured with a torsion balance device.

5. Einstein

(1) put forward the special theory of relativity (classical mechanics is not suitable for microscopic particles and high-speed moving objects)

(2) Put forward the photon theory, successfully explained the law of photoelectric effect, and won the Nobel Prize in physics.

(3) The mass-energy equation is put forward, which provides a theoretical basis for the utilization of nuclear energy.

6. Coulomb: Coulomb's law, the law of interaction between charges, was discovered by torsion balance experiments.

7. Joule and Cold Words

The law of thermal effect when current passes through a conductor has been independently discovered, which is called Joule-Lenz law (this is very unpopular! Give priority to with teaching materials! )

8. Oster

It is found that the charged straight wires placed north and south can deflect the surrounding magnetic needles, which is the so-called current magnetic effect.

9. Ampere: Study the law of current in magnetic field (Ampere's Law), and the hypothesis of molecular current. Magnetic field can act on current.

10, Lorentz: Put forward the viewpoint that moving charge generates magnetic field, and the magnetic field acts on moving charge (Lorentz force).

1 1, Faraday

(1) Discovered the condition and law of current generated by magnetic field-electromagnetic induction phenomenon (there is one in the textbook, but there is no historical reason, so the textbook is the main one! )

(2) Put forward that there is an electric field around the charge, which can be described by electric field, and put forward the concepts of electromagnetic field, magnetic induction line and electric field line.

12, Lengci: the law that determines the direction of the induced current, the law of stagnation: the induced current has such a direction that the magnetic field of the induced current always hinders the change of the magnetic flux that causes the induced current.

13, Henry: Self-induction was discovered (this is also relatively unpopular).

14, Maxwell predicted the existence of electromagnetic waves, pointing out that light is electromagnetic waves, which laid the foundation for the electromagnetic theory of light.

15, Hz:

(1) The existence of electromagnetic waves is confirmed by experiments, and the propagation speed of electromagnetic waves is determined to be equal to the speed of light.

(2) The existence of electromagnetic theory is confirmed.

Planck 16

Put forward the "energy quantum hypothesis"-explain the law of thermal radiation (blackbody radiation) of objects. The emission and absorption of electromagnetic waves are not continuous, but one after another, that is, quantum theory.

17 Bohr: The hypothesis of atomic structure was put forward, and the radiation electromagnetic spectrum of hydrogen atom was successfully explained and predicted.

18, de Broglie: predicted the fluctuation of physical particles, and put forward wave-particle duality, matter wave. De Broglie wave, any moving object has its corresponding wave.

19, Thomson (Xun)

The discovery of electrons by cathode ray tube shows that atoms can be separated and have complex internal structure, and a jujube cake model of atoms (raisin pudding model) is put forward.

20. Rutherford

6. Primary school science knowledge class. What simple and interesting experiments can you do?

Physics class

1. The dispersion of light, such as rainbow, introduces knowledge! Explain that white light is not monochromatic light!

2.2. Concave-convex lenses, students learn lens knowledge with concave lenses and myopia magnifying glasses, but enough is enough!

With regard to gravity, we can use the story of Newton and Apple to illustrate that objects are attracted by gravity, and further illustrate that this force that makes physics fall is gravity.

4.4. Siphon phenomenon is explained by the common sense of changing water in fish tanks!

5.5. The principle of communication device,

6.6. The magic of atmospheric pressure: Why does water flow from the lower part to the mouth and throw it out with a straw to absorb water, which further explains atmospheric pressure.

7.7. Crown block: Generally, primary schools have flagpoles, and there is a crown block at the top of the flagpoles. Then ask the crane about his role.

8.8. Walk in a straight line: use the solar eclipse to introduce problems!

7. Little scientific knowledge

Hello! Examples are as follows: 1. Rabbits beat the ground with their legs to send messages. Most of them beat the ground with their hind legs, which is a way for them to express their feelings to the female rabbits.

2. The biggest monkey in the world is a baboon and the smallest monkey is a bonobo. 3. The real name of "Four Elephants" is Elk, which is a rare animal in China.

4. Why does sorbet get angry? The reason why sorbet bubbles is because there is a lot of invisible water vapor in the outside air. When it comes to cold sorbet, it will liquefy into droplets when it is cold. It seems that the sorbet is bubbling. 5. Why do sunflowers always face the sun? Sunflower stems contain a wonderful auxin.

This auxin is very afraid of light. When it is illuminated, it will go to the backlight side, and the cells on the backlight side will multiply rapidly. Therefore, the backlit side will grow faster than the bright side, which will bend the sunflower to light.

6. Why do cicadas shed their skin? Cicada's shell (exoskeleton) is hard and can't expand with the growth of cicada. When the cicada grows to a certain stage, the cicada's exoskeleton restricts its growth, and the cicada loses its original exoskeleton, which is cicada slough. 7. How do bees make honey? First, the bees spit the sweet juice of the flowers they picked into an empty hive. At night, they suck sweet juice into their honey stomachs to make it, and then spit it out and swallow it. It takes 100~240 times to make sweet honey.

8. Why do the stars twinkle? We see the stars shining, not because the luminosity of the stars has changed, but because of the occlusion of the atmosphere. The atmosphere is between us and the stars. When starlight passes through the atmosphere, it will be affected by the density and thickness of the atmosphere.

The atmosphere is not absolutely transparent, and its transparency will change according to its density. So when we look at the stars through it on the ground, we will see that the stars seem to be flashing.

9. Why do people yawn? When we feel tired, a lot of carbon dioxide has been produced in our bodies. When there is too much carbon dioxide, oxygen must be supplemented to balance the needs of the body.

Because these residual carbon dioxide will affect our body's functional activities, then the body will send out a protective reaction, so we yawn. Yawning is a deep breathing action, which will let us breathe in more oxygen and expel more carbon dioxide than usual, and it can also eliminate fatigue.

10, why can a snake walk without feet? Snakes have many scales, which are the outermost armor on their bodies. Scales are not only used to protect the body, but also to be their "feet".

When a snake crawls forward, its body will be S-shaped. Every scale outside the S-shape will tilt upward to help the snake catch the uneven road when it moves forward.

These scales cooperate with the snake's muscles and can push the body forward, so the snake can walk without feet! 1 1. Why does hair turn white when people get old? There is a substance called melanin in our hair. The more melanin, the darker our hair will be. Without melanin, hair will turn yellow or white.

When human beings reach old age, various functions of the body will gradually decline, and the formation of pigments will be less and less, so the hair will gradually turn white! 12. Why do fireflies glow? Fireflies emit light because there is a luminous body at the end of their abdomen, which is filled with a lot of phosphorus-containing luminescent substances and luminescent enzymes, so that fireflies can emit flashing light. The purpose of fireflies is not only lighting, but also courtship, vigilance and trapping.

This is also a communication tool for them. Different kinds of fireflies emit light in different ways, frequencies and colors, so they can convey different information. 13. Why do you growl when you are hungry? When you are hungry, you will purr. This is because the food you have eaten before has almost been digested. Although the stomach is empty, the gastric juice in the stomach will continue to secrete.

At this time, the contraction of the stomach will gradually expand, and the liquid and gas inside will be stirred up and purr. Don't be embarrassed by your stomach growling next time! Because this is a normal physiological action.

14. Why can't ostriches fly? A giant ostrich, but they can't fly into the sky! This is not because their wings are useless, but because their feathers are too soft and their wings are too small to fly at all. In addition, the ostrich's muscles are underdeveloped and its sternum is flat, which is not conducive to flying.

Ostriches live in Africa. Because they have lived in desert areas for a long time, their bodies gradually evolved into what they are now in order to adapt to the environment. 15. Why can't the food in cans go bad easily? Lunch meat, black bean shad, tomato sauce beans.

They are all delicious canned food, which can be preserved for a long time without deterioration.

This is because the can is sealed, so bacteria can't enter. When people make canned food, they pump all the air out of the canned food and then seal it.

In the absence of air, even if the food inside is contaminated with a little bacteria, they can't survive or reproduce! 16. Why does the baby cry all the time when it is born? Babies cry when they are born, not because they are unhappy, but because they are taking the first breath of air! When babies leave their mother's body and are born, the first breath of air will rush to their throats, violently impact the vocal cords, make them vibrate, and then make a sound similar to crying. 17. Why do lizards keep bouncing backwards when their tails are broken? In order to protect themselves, many lizards also protect their eyes and ears; When some lizards are attacked, their tails will be broken due to the severe contraction of their muscles.

Because there are still some nerves alive in the broken tail, it will keep bouncing, thus distracting the enemy and running away. Don't think that their lives will end like this. In fact, it only takes a few months, and their tails will grow back and continue to live.

18. Why is the squirrel's tail so big? Don't look at the relaxed mouse tail! When the squirrel jumps around the tree, its tail plays a great role. It can keep balance when the squirrel jumps to the tree to avoid falling and being injured.

In addition, this big tail can play a more protective role in winter, tightly surrounding the squirrel's body, which is convenient and practical. 19, why can't a human thumb have one or three knots? Ordinary people have five fingers.