500 words for physics scientific papers.
There are many physical phenomena in life, and many simple phenomena can be answered by what we have learned.
Phenomenon 1: The express train has a safe distance. We are walking on the expressway, so don't get too close to it except for fear that the off-line car will hit us. There is another unexpected reason, which this article will answer.
Phenomenon 2: Take two thin sheets of paper, stick them together and blow them hard. We couldn't blow open the paper, but a quilt appeared. Blow it up? Situation.
Phenomenon 3: With the same flow of water, the flow rate of large-caliber faucet water is very slow, but it can be clearly seen that the flow rate of small-caliber faucet is accelerated. What is the reason?
To sum up, air and water are both fluids, and they have some similarities, both of which follow the basic properties of fluids. There are two very important equations in fluid research: Bernoulli equation and continuity equation. These three phenomena can be easily explained by them. First of all, the basic expression of Bernoulli equation is: P+ 1/2pv+pgh= constant. P refers to the pressure around the fluid, P refers to the density of the fluid itself, and V refers to the velocity of the fluid. In the above phenomenon, water and air can be approximately regarded as ideal fluids, and they are constantly flowing. In the first two cases, pgh can be regarded as a constant, so we can easily get P+ 1/2pv= constant. It is easy to conclude that pressure is inversely proportional to speed. The following are for three people.
Give a concrete explanation to the phenomenon.
Explain phenomenon 1: one of the reasons mentioned is that the air around us is likely to take us away? Push? There was an accident. Why do you say that? When cars pass by us quickly, it has an impact on the surrounding air: it speeds them up. In this case, according to the above, it is easy to know that because the speed is too fast, the pressure of the surrounding air decreases, forming a pressure difference around the car, and things around the car are easily destroyed. News? Get under the car. It's dangerous, so try to pull over on foot.
Phenomenon 2: When two pieces of tissue paper are close together, we regard them as isolated from the outside air. When we blow, a small amount of air between two pieces of paper increases in speed and decreases in pressure, and the surrounding air makes the pieces of paper stick together.
Explain phenomenon 3: with the same flow and volume, it is easy to know SV = S V, which is the continuity equation of ideal fluid. This means that when the ideal fluid flows stably, the product of fluid velocity and cross-sectional area of the flow tube is a constant. So when we reduce the aperture, it will inevitably lead to an increase in speed. According to this principle, there are also great applications in science and technology, such as cutting water guns. With the same water output, this kind of water gun has a small caliber, which makes the water output very fast and contains a lot of kinetic energy.
It has great application in production.
Finally, we should introduce a very practical method: taking water. At home, I saw an adult put a pipe into the water and inhale through his mouth, and the water would flow out by itself. I tried, but it didn't work. Now I aim at the reason: the suction end must be lower than the water end. Why? This is based on the principle of atmospheric pressure. When the tube becomes vacuum after inhalation, the water is submerged by the external atmospheric pressure.
Physics plays a great role in our life. We can learn physics through life and then serve life with physics.
Physical science and technology paper 500 words second
Application of buoyancy
Kongming lantern? Kongming lantern? It was named after Zhuge Liang (Kongming), a resourceful strategist in Liu Bei's army. Shu Han has a history of 1700 years. At that time, Zhu Gekongming was besieged by Sima Yi in Pingyang, unable to send troops out of the city for help. Kong Ming calculated the wind direction, made a floating paper lantern, tied with the message for help, and then escaped as expected, so later generations called this lantern Kong Ming Lantern. Another way of saying this is that this lantern looks like a hat worn by Zhu Gekongming, hence its name. The earliest method of making Kongming lanterns is to make a lantern frame with very thin bamboo strips, and stick it tightly around and at the top with tissue paper, leaving only a round mouth at the bottom. Hang turpentine under a lantern and light it, and the lantern will rise into the air. Because there is fire in the lantern, it was used as a signal for military action at night in ancient wars, just like a signal flare used in modern times.
In the Qing dynasty, the Han people rebelled against the rule of the Manchu government? Anti-clearing and regaining sight? Fight. For the sake of justice, why don't we just forget it? Kongming lantern? As a command signal for unified action. In the past, the Han people put? Kongming lantern? Used to communicate, and then people put it away? Kongming lantern? As a folk entertainment, modern people regard Kongming Lantern as a blessing. The wishes of men, women and children to write blessings by hand symbolize the bumper harvest and happiness every year. The structure of Kongming Lantern can be divided into two parts: the main body is mostly bamboo grates, followed by cotton paper or paper paste, and the underframe is bamboo grates. Kongming lanterns can be large or small, round or rectangular.
Generally speaking, Kongming lanterns are barrel-shaped made of bamboo pieces, surrounded by thin white paper, and their openings are downward. When taking off with a light, tie a piece of coarse cloth or gold paper stained with kerosene or peanut oil in the middle of the bracket at the bottom, and light the fuel before flying. After the fire in the lamp burns for a while, it will produce hot air and the lanterns will expand. When released, the whole lantern will fly in Ran Ran. If the weather is clear and the kerosene at the bottom burns out, the lanterns will automatically fall. The principle of Kongming Lantern is the same as that of hot air balloon, which uses the buoyancy of hot air to lift the sphere. But why does hot air float? We can use Archimedes principle to explain that when an object has the same volume as air, but its weight (density) is less than air, it can fly, which is the same as the buoyancy of water.
When the air in the ball is heated, due to the expansion of the air, part of the air in the ball will flow out of the ball, making the density of the internal air less than that of the external air, so that the ball filled with hot air will fly.
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