磁铁可以吸引铁， 钴， 镍
任何飞机起飞前都必须产生大于自身重力的升力。这是飞机飞行的基本原理。就像我们之前提到的飞机可分为两类：轻于空中的飞机和重于空中的飞机。比飞机轻的飞机 例如气球， 飞艇 等等。，The main part is a big airbag,Fill the middle with a gas that is less dense than air (such as hot air, hydrogen, etc.),This is just like the toy hydrogen balloon when we were young,Can rely on the static buoyancy of the air to rise into the air.Well over a thousand years ago,Our ancestors invented the Kongming Lantern, an ingenious device that lifted into the air with the help of hot air.Can be regarded as the originator of lighter-than-air aircraft.
Why can wind both aid and extinguish fires?
Why high winds may bring fires,But sometimes it can be used for fire fighting?What is the principle of a wind fire extinguisher?Let us find out together.
How is fire produced?
To understand the principles of fire-assisting and extinguishing,We must first understand the basic principles of combustion.Combustion is a violent oxidation-reduction reaction,Usually it emits flame, visible light and smoke at the same time.The combustion of materials to produce a fire needs to meet three necessary conditions at the same time: combustibles, combustion aids and ignition sources.
in life,50 physics tips that children are most interested in
1.Cut vegetables quickly after sharpening the knife,That is, the smaller the force-receiving area of the same pressure, the greater the pressure.
2.Boiling water bubbles rise more and more,That is, as the depth decreases, the pressure of the water decreases.
3.The dumplings will float to the surface when they are cooked.The density becomes smaller,The volume becomes larger,Buoyancy becomes greater.
Sound and optics of interesting physical phenomena in life
Physics is closely related to life,Each interesting and seemingly accustomed life phenomenon contains different physical meanings.Lao Hu collected 12 interesting life phenomena including 12 physical phenomena,And it's a compulsory physical knowledge for the senior high school entrance examinationCome and find out!
1.But after hearing it,I don't see him-as sound waves are spreading,When the size of the obstacle is smaller than the wavelength,Significant diffraction can occur.The height of the general wall is a few meters,The wavelength of the sound wave is greater than the height of the wall,and so,It can go around the ground and high walls,So that people outside the wall can hear; and the wavelength of the light wave is shorter (about 10-6 meters),Much smaller than the height of the wall,Therefore, the light emitted from the human body cannot be diffracted to the outside of the wall,The people outside the wall cannot see the people inside.
Long knowledge!How to use physics knowledge,Reduce waste more scientifically?
"One porridge, one meal,When thinking is not easy; half a thread and half a thread,Heng Nian's material resources are difficult."Be strict with economy and oppose waste,It is a traditional virtue of the Chinese nation for thousands of years.
In order to thoroughly implement the spirit of General Secretary Jinping's important instructions,Resolutely curb "waste on the tip of the tongue" in the catering process,Accelerate the formation of a social trend of "shameful waste and pride in saving".recently,The Women's Federation of Hebei Province will present various forms of "CD Action" with the theme of "Saving Food".
At noon on the day of hoeing,Sweat drips down the soil,Who knows Chinese food,Every bit is hard.
Mechanics and temperature of interesting physical phenomena in life
Physics is closely related to life,Each interesting and seemingly accustomed phenomenon has different physical meanings behind it.Lao Hu collected 19 interesting life phenomena,Every life phenomenon contains a compulsory physics knowledge in the senior high school entrance examination,Come and find out!
1.Small weighing heavy weight——according to the principle of lever balance,The force is inversely proportional to the force arm,If the power arm is a fraction of the resistance arm,The power is several times the resistance.If the force arm of the weighing mound is very large,So it is completely possible to "should a thousand catties in four or two ways".
The secret of boulders in the chest
I often see street performers performing shows with broken boulders on their chests in film and television dramas.I saw a person lying on a bed full of steel nails,Place a big stone on the chest,Another person woke up a sledgehammer,I saw the stone was broken,People are safe and sound.This is the so-called "golden bell jar,Iron cloth shirt".So how is this kind of kung fu made?
1. Knowledge reserve and term explanation
1. Pressure: refers to the force generated by the object on the supporting surface,This force is generally not equal to the gravity of the object,仅当放置在水平表面上时，物体在接触表面上的压力等于物体的重力。
长笛是一种乐器，历史的。在古时候，人们过去常常使用更长的动物的骨头，例如， 鸟的翼骨和腿骨构成长笛。舞阳县出土的竖骨笛子 河南省由鸟肢骨头制成，它已有8多年的历史000年。直到今天中国长笛的形状非常成熟，身体通常是用竹子做的，有一个气孔， 膜孔六个指孔还有两个前音孔和两个后音孔。