Presentation for a 9th grade physics lesson on the topic “Jet propulsion”
Author of the material: Olga Ivanovna Marchenko, physics teacher of the highest qualification category, Municipal Educational Institution-Secondary School No. 3, Marx, Saratov Region
Marks, 2015.
Lesson of “discovery” of new knowledge 9th grade Marchenko Olga Ivanovna, physics teacher 2013
Jet propulsion
Goals. Educational: 1. Give the concept of jet propulsion, 2. Give examples of jet propulsion in nature and technology. 3. Describe the purpose, structure, operating principle, and use of missiles. 4. Be able to determine the speed of a rocket, be able to use the law of conservation of momentum and Newton’s III law. 5. Show the significance of the works of K.E. Tsiolkovsky. and Korolev S.P. in the development of space rocket propulsion. Educational: show the practical significance of physical knowledge on the topic “Jet propulsion”; increase the labor and creative activity of students, expand their horizons through self-education, Developmental: develop the ability to analyze facts when observing phenomena; develop the skills of cultural dialogue, express and justify your point of view, defend the correctness of judgments, analyze the results.
Heliocentric system of the world
Teacher. - You know how our solar system works. By the way, how does it work?
- Now it’s time to begin a detailed study of the surroundings of the solar system
- Let's find out what the Sun is. What is the Sun?
What is the name of such a structure? Why is it called that?
- Do you know which planets are part of the solar system? By the way, which ones?
I. Motivation for educational activities.
(nearest star)
Road to space. The spaceship was flying along the space route and the oncoming stars sparkled and went out. How could it, from what flights and wanderings, suddenly find itself in interstellar space?..
-It's time to go into space!
Jet propulsion
It's time to go into space! -Find out: How to “get” to space.
The spaceship was flying along the space route and the oncoming stars sparkled and went out. How could it, from what flights and wanderings, suddenly find itself in interstellar space?..
But first, let's find out why we can move at all?
1. Why can we move on earth?
- push off from the ground
1. Why can we move - on water?
push off from the water
3.Why can we travel through the air?
- push off from the air
What to start from in space? How to move there?
Task 1. Jet ball
Conclusion. The air comes out in one direction and the ball moves in the other.
Let's do a little research and find out what a body can push off from if there is nothing to push off from.
Task 1. Jet balloon Two people will take the fishing line on which the tube with the balloon is attached and pull it. Inflate the balloon and release it. What happened to the ball? What caused the ball to start moving?
(air separated from it)
Task 2. Jet stroller.
Conclusion: The air comes out in one direction - the stroller. moves to another.
Take a cart with a balloon attached to it. Inflate the balloon through a straw. Place the cart on the desk and release the ball
What happened to the cart? What caused the cart to start moving?
(air separated from it)
Lesson topic: Jet propulsion
Reactive motion is a movement that occurs when any part of it is separated from the body at a certain speed.
Physical education minute
Show your imagination and try to depict: octopus, squid, jellyfish, cucumber.
"Mad" cucumber
Octopus
Squid
EXAMPLES OF JET MOTION IN NATURE: Jet motion is characteristic of octopuses, squids, cuttlefish, jellyfish - all of them, without exception, use the reaction (recoil) of an ejected stream of water for swimming
Jet propulsion in technology
FROM THE HISTORY OF JET PROpulsion The first gunpowder fireworks and signal flares were used in China in the 10th century. In the 18th century, combat missiles were used during hostilities between India and England, as well as in the Russian-Turkish wars. Jet propulsion is now used in airplanes, rockets and spacecraft
Rocket launcher
Rocket
Exercise. Open the textbook p. 84 “Design and principle of operation of a launch vehicle”
Examples of jet propulsion in technology
So, we have found the way to space - this is jet propulsion
great Russian scientist and inventor, discovered the principle of jet propulsion, who is rightfully considered the founder of rocket technology
Konstantin Eduardovich Tsiolkovsky (1857-1935)
Founders of astronautics:
Sergei Pavlovich Korolev (1907-1966)
spaceship designer
Founders of astronautics:
Yuri Alekseevich Gagarin1934-1968
The first cosmonaut in the history of mankind made the first manned space flight on April 12, 1961 on the Vostok spacecraft.
Founders of astronautics.
Slide 1
Slide 2
Derivation of the formula for the speed of a rocket during takeoff According to Newton's third law: F1 = - F2, where F1 is the force with which the rocket acts on hot gases, and F2 is the force with which the gases repel the rocket. The moduli of these forces are equal: F1 = F2. It is the force F2 that is the reactive force. Let's calculate the speed that the rocket can acquire. If the momentum of the ejected gases is equal to Vg mg, and the momentum of the rocket is Vр mр, then according to the law of conservation of momentum, we obtain: Vg mg = Vр mр, Where does the rocket speed come from: Vр = Vг mг / mр
Slide 3
Konstantin Eduardovich Tsiolkovsky The idea of using rockets for space flights was put forward at the beginning of the 20th century by the Russian scientist, inventor and teacher Konstantin Eduardovich Tsiolkovsky. Tsialkovsky developed the theory of rocket motion, derived a formula for calculating their speed, and was the first to propose the use of multi-stage rockets.
Slide 4
The first cosmonaut on the planet and the chief designer of domestic rocket and space technology, Sergei Pavlovich Korolev, is a Soviet scientist and designer, director of all space flights. Yuri Alekseevich Gagarin, the first cosmonaut, circled the Earth on April 12, 1961 in 1 hour 48 minutes on the Vostok spacecraft.
Slide 5
Reactive movement Reactive movement occurs due to the fact that some part of it is separated from the body and moves, as a result of which the body itself acquires an oppositely directed impulse.
Slide 6
The principle of jet propulsion finds wide practical application in aviation and astronautics. There is no medium in outer space with which a body could interact and thereby change the direction and magnitude of its speed. Therefore, only jet aircraft can be used for space flights, i.e. rockets.
Slide 7
A visual diagram of the design of a single-stage rocket. Any rocket, regardless of its design, always has a shell and fuel with an oxidizer. The figure shows a cross-section of a rocket. We see that the rocket shell includes the payload (spacecraft), instrument compartment and engine (combustion chamber, pumps, etc.).
Slide 8
Multistage rockets In space flight practice, multistage rockets are usually used, which develop much higher speeds and are designed for longer flights. The figure shows a diagram of such a rocket. After the fuel and oxidizer of the first stage are consumed, this stage is automatically discarded and the second stage engine takes over, etc. Reducing the overall mass of the rocket by discarding an already unnecessary stage saves fuel and oxidizer and increases the rocket's speed.
Application of jet propulsion in nature Many of us in our lives have encountered jellyfish while swimming in the sea. But few people thought that jellyfish also use jet propulsion to move. And often the efficiency of marine invertebrate animals when using jet propulsion is much higher than that of technological inventions.
Cuttlefish Cuttlefish, like most cephalopods, moves in water in the following way. She takes water into the gill cavity through a side slit and a special funnel in front of the body, and then energetically throws out a stream of water through the funnel. The cuttlefish directs the funnel tube to the side or back and, quickly squeezing water out of it, can move in different directions.
Squid Squid is the largest invertebrate inhabitant of the ocean depths. It moves according to the principle of jet propulsion, absorbing water, and then pushing it with enormous force through a special hole - a “funnel”, and at high speed (about 70 km/h) it pushes backwards. At the same time, all ten tentacles of the squid are gathered into a knot above its head and it takes on a streamlined shape.
Flying squid This is a small animal the size of a herring. It chases fish with such speed that it often jumps out of the water, skimming over its surface like an arrow. Having developed maximum jet thrust in the water, the pilot squid takes off into the air and flies over the waves for more than fifty meters. The apogee of a living rocket's flight lies so high above the water that flying squids often end up on the decks of ocean-going ships. Four to five meters is not a record height to which squids rise into the sky. Sometimes they fly even higher.
Octopus Octopuses can also fly. French naturalist Jean Verani saw how an ordinary octopus accelerated in an aquarium and suddenly jumped out of the water backwards. Having described an arc about five meters long in the air, he plopped back into the aquarium. When picking up speed to jump, the octopus moved not only due to jet thrust, but also rowed with its tentacles.
Crazy cucumber In southern countries (and here on the Black Sea coast too) a plant called “crazy cucumber” grows. As soon as you lightly touch a ripe cucumber-like fruit, it bounces off the stalk, and through the resulting hole, liquid with seeds flies out of the fruit at a speed of up to 10 m/s. The mad cucumber (otherwise called the “ladies’ pistol”) shoots at more than 12 m.
Presentation on physics at school level (9th grade) on the topic "Jet propulsion" in ppt format (powerpoint 2003), contains 23 slides.
Fragments from the presentation
- Body impulse. Impulse of force.
- Law of conservation of momentum.
- Jet propulsion:
- jet propulsion in nature and technology;
- history of the development of jet propulsion;
- the importance of space exploration.
“I tell a person: believe in yourself!
You can do everything!
You can know all the secrets of eternity. become the master of all the riches of nature. You have wings behind your back. Swing them! Well, swing it and you will be happy, powerful and free..."
K. E. Tsiolkovsky
Body impulse, force impulse
- The momentum of a body is a vector physical quantity, which is a measure of mechanical motion, numerically equal to the product of the mass of the body and the speed of its movement.
- Force impulse is a vector physical quantity that is a measure of the action of force over a certain period of time.
- The change in the momentum of the body is equal to the impulse of the force.
- When bodies interact, their impulses can change.
Conditions for applying the law of conservation of momentum:
- The system must be closed.
- External forces acting on the bodies of the system are compensated or their action can be neglected.
- Performed in inertial reference systems.
Jet propulsion
All types of movement are impossible without the interaction of the bodies of a given system with the environment. And for the implementation of jet motion, no interaction of the body with the environment is required.- The movement of a body resulting from the separation of part of its mass from it at a certain speed is called reactive.
- The principles of jet propulsion find wide practical application in aviation and astronautics.
Sergei Pavlovich Korolev was the largest designer of rocket and space systems. Under his leadership, the world's first artificial satellites of the Earth, Moon and Sun, the first manned spacecraft and the first manned spacewalk were launched.
The importance of space exploration
- Using satellites for communications. Implementation of telephone and television communications.
- Using satellites for navigation of ships and aircraft.
- The use of satellites in meteorology and for studying processes occurring in the atmosphere; forecasting natural phenomena.
- Use of satellites for scientific research, implementation of various technological processes in conditions of weightlessness, clarification of natural resources.
- Using satellites to study space and the physical nature of other bodies in the solar system
Jet propulsion in nature and technology
ABSTRACT ON PHYSICS
Jet propulsion- movement that occurs when any part of it is separated from the body at a certain speed.
Reactive force occurs without any interaction with external bodies.
Application of jet propulsion in nature
Many of us in our lives have encountered jellyfish while swimming in the sea. In any case, there are quite enough of them in the Black Sea. But few people thought that jellyfish also use jet propulsion to move. In addition, this is how dragonfly larvae and some types of marine plankton move. And often the efficiency of marine invertebrate animals when using jet propulsion is much higher than that of technological inventions.
Jet propulsion is used by many mollusks - octopuses, squids, cuttlefish. For example, a sea scallop mollusk moves forward due to the reactive force of a stream of water thrown out of the shell during a sharp compression of its valves.
Octopus
Cuttlefish
Cuttlefish, like most cephalopods, moves in water in the following way. She takes water into the gill cavity through a side slit and a special funnel in front of the body, and then energetically throws out a stream of water through the funnel. The cuttlefish directs the funnel tube to the side or back and, quickly squeezing water out of it, can move in different directions.
The salpamarine animal with a transparent body, when moving, receives water through the front opening, and the water enters a wide cavity, inside of which the gills are stretched diagonally. As soon as the animal takes a large sip of water, the hole closes. Then the longitudinal and transverse muscles of the salp contract, the whole body contracts, and water is pushed out through the posterior opening. The reaction of the escaping jet pushes the salpa forward.
The squid's jet engine is of greatest interest. The squid is the largest invertebrate inhabitant of the ocean depths. Squids have achieved the highest perfection in jet navigation. Even their body, with its external forms, copies the rocket (or better said, the rocket copies the squid, since it has indisputable priority in this matter). When moving slowly, the squid uses a large diamond-shaped fin that periodically bends. It uses a jet engine to throw quickly. Muscle tissue - the mantle surrounds the mollusk's body on all sides; the volume of its cavity is almost half the volume of the squid's body. The animal sucks water inside the mantle cavity, and then sharply throws out a stream of water through a narrow nozzle and moves backwards with high speed pushes. At the same time, all ten tentacles of the squid are gathered into a knot above its head, and it takes on a streamlined shape. The nozzle is equipped with a special valve, and the muscles can rotate it, changing the direction of movement. The squid engine is very economical, it is capable of reaching speeds of up to 60 - 70 km/h. (Some researchers believe that even up to 150 km/h!) No wonder the squid is called a “living torpedo.” By bending the bundled tentacles to the right, left, up or down, the squid turns in one direction or another. Since such a steering wheel is very large compared to the animal itself, its slight movement is enough for the squid, even at full speed, to easily dodge a collision with an obstacle. A sharp turn of the steering wheel - and the swimmer rushes in the opposite direction. So he bent the end of the funnel back and now slides head first. He bent it to the right - and the jet push threw him to the left. But when you need to swim quickly, the funnel always sticks out right between the tentacles, and the squid rushes tail first, just as a crayfish would run - a fast walker endowed with the agility of a racer.
If there is no need to rush, squids and cuttlefish swim with undulating fins - miniature waves run over them from front to back, and the animal glides gracefully, occasionally pushing itself also with a stream of water thrown out from under the mantle. Then the individual shocks that the mollusk receives at the moment of eruption of water jets are clearly visible. Some cephalopods can reach speeds of up to fifty-five kilometers per hour. It seems that no one has made direct measurements, but this can be judged by the speed and flight range of flying squids. And it turns out that octopuses have such talents in their family! The best pilot among mollusks is the squid Stenoteuthis. English sailors call it flying squid (“flying squid”). This is a small animal about the size of a herring. It chases fish with such speed that it often jumps out of the water, skimming over its surface like an arrow. He resorts to this trick to save his life from predators - tuna and mackerel. Having developed maximum jet thrust in the water, the pilot squid takes off into the air and flies over the waves for more than fifty meters. The apogee of a living rocket's flight lies so high above the water that flying squids often end up on the decks of ocean-going ships. Four to five meters is not a record height to which squids rise into the sky. Sometimes they fly even higher.
The English mollusk researcher Dr. Rees described in a scientific article a squid (only 16 centimeters long), which, having flown a fair distance through the air, fell on the bridge of a yacht, which rose almost seven meters above the water.
It happens that a lot of flying squids fall on the ship in a sparkling cascade. The ancient writer Trebius Niger once told a sad story about a ship that allegedly sank under the weight of flying squids that fell on its deck. Squids can take off without acceleration.
Octopuses can also fly. French naturalist Jean Verani saw how an ordinary octopus accelerated in an aquarium and suddenly jumped out of the water backwards. Having described an arc about five meters long in the air, he plopped back into the aquarium. When picking up speed to jump, the octopus moved not only due to jet thrust, but also rowed with its tentacles.
Baggy octopuses swim, of course, worse than squids, but at critical moments they can show a record class for the best sprinters. California Aquarium staff tried to photograph an octopus attacking a crab. The octopus rushed at its prey with such speed that the film, even when filming at the highest speeds, always contained grease. This means that the throw lasted hundredths of a second! Typically, octopuses swim relatively slowly. Joseph Seinl, who studied the migrations of octopuses, calculated: an octopus half a meter in size swims through the sea at an average speed of about fifteen kilometers per hour. Each jet of water thrown out of the funnel pushes it forward (or rather, backward, since the octopus swims backwards) two to two and a half meters.
Jet motion can also be found in the plant world. For example, the ripened fruits of the “mad cucumber”, with the slightest touch, bounce off the stalk, and a sticky liquid with seeds is forcefully thrown out of the resulting hole. The cucumber itself flies off in the opposite direction up to 12 m.
Knowing the law of conservation of momentum, you can change your own speed of movement in open space. If you are in a boat and you have several heavy stones, then throwing stones in a certain direction will move you in the opposite direction. The same will happen in outer space, but there they use jet engines for this.
Everyone knows that a shot from a gun is accompanied by recoil. If the weight of the bullet were equal to the weight of the gun, they would fly apart at the same speed. Recoil occurs because the ejected mass of gases creates a reactive force, thanks to which movement can be ensured both in air and in airless space. And the greater the mass and speed of the flowing gases, the greater the recoil force our shoulder feels, the stronger the reaction of the gun, the greater the reactive force.
Application of jet propulsion in technology
For many centuries, humanity has dreamed of space flight. Science fiction writers have proposed a variety of means to achieve this goal. In the 17th century, a story by the French writer Cyrano de Bergerac about a flight to the moon appeared. The hero of this story reached the Moon in an iron cart, over which he constantly threw a strong magnet. Attracted to him, the cart rose higher and higher above the Earth until it reached the Moon. And Baron Munchausen said that he climbed to the moon along a bean stalk.
At the end of the first millennium AD, China invented jet propulsion, which powered rockets - bamboo tubes filled with gunpowder, they were also used as fun. One of the first car projects was also with a jet engine and this project belonged to Newton
The author of the world's first project of a jet aircraft intended for human flight was the Russian revolutionary N.I. Kibalchich. He was executed on April 3, 1881 for his participation in the assassination attempt on Emperor Alexander II. He developed his project in prison after being sentenced to death. Kibalchich wrote: “While in prison, a few days before my death, I am writing this project. I believe in the feasibility of my idea, and this faith supports me in my terrible situation... I will calmly face death, knowing that my idea will not die with me.”
The idea of using rockets for space flights was proposed at the beginning of this century by the Russian scientist Konstantin Eduardovich Tsiolkovsky. In 1903, an article by Kaluga gymnasium teacher K.E. appeared in print. Tsiolkovsky “Exploration of world spaces using reactive instruments.” This work contained the most important mathematical equation for astronautics, now known as the “Tsiolkovsky formula,” which described the motion of a body of variable mass. Subsequently, he developed a design for a liquid-fuel rocket engine, proposed a multi-stage rocket design, and expressed the idea of the possibility of creating entire space cities in low-Earth orbit. He showed that the only device capable of overcoming gravity is a rocket, i.e. a device with a jet engine that uses fuel and oxidizer located on the device itself.
Jet engine is an engine that converts the chemical energy of fuel into the kinetic energy of a gas jet, while the engine acquires speed in the opposite direction.
The idea of K.E. Tsiolkovsky was implemented by Soviet scientists under the leadership of Academician Sergei Pavlovich Korolev. The first artificial Earth satellite in history was launched by rocket in the Soviet Union on October 4, 1957.
The principle of jet propulsion finds wide practical application in aviation and astronautics. In outer space there is no medium with which a body could interact and thereby change the direction and magnitude of its speed, therefore only jet aircraft, i.e., rockets, can be used for space flights.
Rocket device
The motion of a rocket is based on the law of conservation of momentum. If at some point in time any body is thrown away from the rocket, it will acquire the same impulse, but directed in the opposite direction
Any rocket, regardless of its design, always has a shell and fuel with an oxidizer. The rocket shell includes the payload (in this case a spacecraft), the instrument compartment and the engine (combustion chamber, pumps, etc.).
The main mass of the rocket is fuel with an oxidizer (the oxidizer is needed to maintain fuel combustion, since there is no oxygen in space).
Fuel and oxidizer are supplied to the combustion chamber using pumps. Fuel, when burned, turns into a gas of high temperature and high pressure. Due to the large pressure difference in the combustion chamber and in outer space, gases from the combustion chamber rush out in a powerful jet through a specially shaped socket called a nozzle. The purpose of the nozzle is to increase the speed of the jet.
Before the rocket launches, its momentum is zero. As a result of the interaction of the gas in the combustion chamber and all other parts of the rocket, the gas escaping through the nozzle receives some impulse. Then the rocket is a closed system, and its total momentum must be zero after launch. Therefore, the entire shell of the rocket that is in it receives an impulse equal in magnitude to the impulse of the gas, but opposite in direction.
The most massive part of the rocket, intended for launch and acceleration of the entire rocket, is called the first stage. When the first massive stage of a multi-stage rocket exhausts all its fuel reserves during acceleration, it separates. Further acceleration is continued by the second, less massive stage, and it adds some more speed to the speed previously achieved with the help of the first stage, and then separates. The third stage continues to increase speed to the required value and delivers the payload into orbit.
The first person to fly in outer space was a citizen of the Soviet Union, Yuri Alekseevich Gagarin. April 12, 1961 He circled the globe on the Vostok satellite.
Soviet rockets were the first to reach the Moon, circled the Moon and photographed its side invisible from Earth, and were the first to reach the planet Venus and deliver scientific instruments to its surface. In 1986, two Soviet spacecraft, Vega 1 and Vega 2, closely examined Halley's Comet, which approaches the Sun once every 76 years.