Female infidelity is a rather complex phenomenon. First, with the social ...
Slide 1
Solving problems. Gravitational forces. 9-10 grade.
Slide 2
Does the force of attraction to the Sun act on a person? How to explain the occurrence of ebb and flow in the ocean? Explain the physical meaning of the gravitational constant?
Frontal student survey:
Slide 3
How many times will the force of attraction between bodies change with an increase in the distance between them by 5 times? A. Will increase 5 times; B. Will decrease by 5 times; C. Will decrease 25 times. 2. How many times will the force of attraction between bodies change with a decrease in the mass of each body by 2 times? A. Will increase 2 times; B. Will decrease by 4 times; C. Will decrease by 4 times.
Complete the task:
Slide 4
3. How many times will the force of attraction between bodies change with an increase in the distance between them by 2 times and an increase in the mass of one of them by 4 times? A. Increase by 8 times B. Will not change C. Decrease by 2 times How many times will the force of attraction between bodies change with a 2-fold decrease in the mass of one of the bodies and a 2-fold increase in the distance between them? A. Increase by 2 times B. Decrease by 4 times C. Decrease by 8 times
Slide 5
Solve the problem:
1. A force of 720 N acts on an astronaut on the Earth's surface. What gravitational force will act on the same astronaut in a spacecraft located at a distance of two Earth radii from the Earth's surface? A) 180 N B) 80 N C) 360 N D) 240 N
Slide 6
2. Two bodies weighing 103 kg and 2 · 103 kg are at a distance R from each other and are attracted with a force F. What is the force of attraction for bodies weighing 2 · 103 kg and 4 · 103 kg, located at the same distance R? A) F B) 2F C) 4F D) 8F
Slide 7
3. On the surface of the Earth, a gravity force of 1000 N acts on the astronaut in a spacesuit. On the surface of the planet, the radius is 2 times less than that of the Earth and the mass is 2 times less than the mass of the Earth, the force of gravity acting on this astronaut will be equal to: A) 500 N B) 1000 H V) 2000 N D) 4000 N
Slide 8
4. Which of the following statements are correct? A) The force of universal gravitation keeps the planets in their orbits around the Sun B) The force of universal gravitation will change if the density of one of the attracting bodies changes C) In free fall, a heavier body will fall faster than a lighter one if dropped from the same height D) If the body is not affected by gravity, then the body is in a state of weightlessness
1 slide
Solving problems. Gravitational forces. 9-10 grade.
2 slide
Does the force of attraction to the Sun act on a person? How to explain the occurrence of ebb and flow in the ocean? Explain the physical meaning of the gravitational constant? Frontal student survey:
3 slide
How many times will the force of attraction between bodies change with an increase in the distance between them by 5 times? A. Will increase 5 times; B. Will decrease by 5 times; C. Will decrease 25 times. 2. How many times will the force of attraction between bodies change with a decrease in the mass of each of the bodies by 2 times? A. Will increase 2 times; B. Will decrease by 4 times; C. Will decrease by 4 times. Complete the task:
4 slide
3. How many times will the force of attraction between bodies change with an increase in the distance between them by 2 times and an increase in the mass of one of them by 4 times? A. Increase by 8 times B. Will not change C. Decrease by 2 times How many times will the force of attraction between bodies change with a 2-fold decrease in the mass of one of the bodies and a 2-fold increase in the distance between them? A. Increase by 2 times B. Decrease by 4 times C. Decrease by 8 times
5 slide
Solve the problem: 1. A force of 720 N acts on an astronaut on the Earth's surface. What gravitational force will act on the same astronaut in a spacecraft located at a distance of two Earth radii from the Earth's surface? A) 180 N B) 80 N C) 360 N D) 240 N
6 slide
Solve the problem: 2. Two bodies weighing 103 kg and 2 · 103 kg are at a distance R from each other and are attracted with a force F. What is the force of attraction of bodies weighing 2 · 103 kg and 4 · 103 kg, located at the same distance R ? A) F B) 2F C) 4F D) 8F
7 slide
Solve the problem: 3. On the surface of the Earth, a gravity force of 1000 N acts on the astronaut in a spacesuit. On the surface of the planet, the radius is 2 times less than that of the Earth and the mass is 2 times less than the mass of the Earth, the force of gravity acting on this astronaut will be equal to: A) 500 N B) 1000 N C) 2000 N D) 4000 N
8 slide
Solve the problem: 4. Which of the following statements are correct? A) The force of universal gravitation keeps the planets in their orbits around the Sun B) The force of universal gravity will change if the density of one of the attracting bodies is changed C) In free fall, a heavier body will fall faster than a lighter one if dropped from the same height D) If the body is not affected by gravity, then the body is in a state of weightlessness
Lesson objectives: to acquaint students with the historical facts leading to the discovery of the law of universal gravitation, to study the areas of application of the law, its significance for science.
Lesson Objectives:
Educational: to ensure the assimilation by students of the physical meaning of the law of universal gravitation, the gravitational constant, the study of formulas for the acceleration of free fall and the speed of movement of satellites, to teach how to apply the law in solving problems.
Developing:
Development of cognitive interest using historical materials and physical terms.
development of the ability to see physical phenomena in the surrounding world.
The development of synthesizing thinking - the development of the ability to establish uniform, common features and the properties of the whole, draw up a plan of the material studied, draw conclusions.
Formation of skills to highlight the main thing, draw up a plan, abstracts, take notes.
Educational:
Education of motives for learning, a positive attitude to knowledge.
Fostering discipline.
Lesson type - a lesson in studying new material with elements of independent search and practical activities of students.
Lesson type - conversation.
Equipment:
Multimedia system.
Presentation.
The lesson "Studying the nature of gravitational forces" was prepared for the 10th grade, but can be used in the 9th grade when studying this topic, as well as in various elective courses, thematic events.
Plan-Timing of the lesson.
Stages of the lesson.
Techniques and methods.
I. Organizational moment.
Motivation.
Conversation. Creation of a positive attitude towards learning activities. Monitoring the emotional state of students.
1. Statement of the educational problem.
Conversation. Formulation of the goals and objectives of the training session.
2. Organization of the perception of educational material
Working with the presentation and the textbook: filling out the reference note (or notebook).
Homework.
Recording in support notes homework, its discussion and deadlines.
1. Summing up.
Generalization and systematization of the work performed.
2. Mutual evaluation of work in the classroom.
Mark absent on training session and grading.
During the classes:
I. Organization of the beginning of the lesson.
Announcement of the topic of the lesson. Goal setting.
II. Learning new material.
Why do all bodies fall to Earth? This question has occupied even ancient scholars. In ancient times, people considered the Earth to be a plane on which the firmament rests.
This idea arose from a direct visual impression. Seeing that all the bodies on the earth's surface are falling down, they decided that there is an "up" and "down" in the Universe. This is why the bodies fall. This idea was closely related to the concept of the absolute "top" and "bottom", which were quite consistent with the views of the slave-owning society of the ancient world.
Of the ancient sciences, only at the end of the 13th century was it allowed to teach the teachings of the Greek philosopher Aristotle. However, this scientist already knew, for example, that the Earth is a sphere, and this contradicted the biblical view of the structure of the world. Therefore, the writings of Aristotle were provided with various commentaries, bringing his teaching in harmony with the Bible. Greek astronomers took all the movements of cosmic bodies that they saw as real. To explain the loop-like motion of the planets, a very complex geometric scheme was invented: the planet seems to be moving in a circle, the center of which revolves around the Earth. This was the system of the world of the Greek astronomer Claudius Ptolemy, which dominated science until the middle of the 16th century.
In the 16th century, the Polish scientist Nicolaus Copernicus decided to "wrap up" the mechanism of the universe. Isn't it easier to explain the complex paths of the planets if we assume that the Earth describes a circular path around the Sun? Nicolaus Copernicus proved that the geocentric system of the world, (with the Earth as its center), put forward by the Greek scientist Claudius Ptolemy and dominating monopoly for almost one and a half thousand years, is incorrect. Copernicus has the honor of creating modern ideas about the structure Solar system... Copernicus worked all his life to develop his own system of the world. He described it in his book On the Conversion of the Heavenly Spheres, which he did not dare to publish for a long time, so as not to incur persecution of the Catholic Church. His book was published in 1543. She was a real revelation for scientists. It contained in itself the answer to those of them who in
in despair, they thought that a person could not know the movements of heavenly bodies and that knowledge of movements was available to him only in the "sublunary" world, that is, on Earth. But Copernicus' conception of the universe did not differ from that of his contemporaries.
In 1610, the entire cultural world was excited by the amazing news: a professor at the University of Padua arranged a tube through which one could see in the sky hitherto unknown stars and planetary satellites. And the telescope aimed at the sky has pushed the limits of the world far. Galileo was in a hurry to inform the whole world about his discoveries by publishing his famous "Star Messenger". He told in it about mountains, depressions, heights on the surface of the moon. The Star Messenger revealed the secret of the luminous Milky Way, which some ancient scientists believed to be the place of the "soldering" of the crystal celestial spheres. Finally, he reported the news of a new world of planets - Jupiter, surrounded by satellites revolving around him. But what force keeps the planet in orbit? At that time no one tried to answer this question yet.
The Danish astronomer Tycho Brahe headed the Uraniborg observatory, which he built on the island of Ven in the Øresund Strait, near Copenhagen, and supplied the excellent instruments made under his direction. Here, for 21 years, he observed stars, planets and comets, making determination of the positions of the luminaries with a very high precision... This is his main merit. Brahe did not recognize the heliocentric system of the world and instead proposed another one, representing an unsuccessful combination of the teachings of Ptolemy with the system of N. Copernicus (the sun moves around the Earth, standing in the center of the universe, and the planet around the sun). In 1597, Brahe was forced to leave Denmark (after his departure, the Uraniborg Observatory was abandoned) and after two years in Germany, he moved to Prague. Here I. Kepler joined him as assistants, who, after the death of Brahe, had valuable observations.
In 1609, the German astronomer Johannes Kepler, completing the work of Copernicus, was able to unravel the secrets of the orbits along which the planets move around the Sun, and their satellites around the planets themselves. These orbits turned out to be not circles, as Copernicus believed, but ellipses.
As science developed, man recognized and studied all the new forces acting in nature. However, without a doubt, the very first of the forces that became known to man and what struck his imagination was the force of gravity. Who among us has not fallen to the ground under the influence of this force, has not faced it every day, every moment? It is impossible to imagine life on earth without the force of gravity.
But although the manifestations of the force of gravity have been known to people for as long as they exist, science discovered this force relatively recently, a little over 300 years ago. In 1687, when the historical book of the great English scientist Isaac Newton "Mathematical principles of natural philosophy" was published (that was the name of the science of nature, now known as physics).
To derive the laws of motion of the planets, it was necessary to know how the force of gravity changes with a change in distance. Newton suggested that the force of gravity changes in the same way as the illumination of an object when approaching or moving away from a light source: if the distance becomes three times greater, the force of gravity decreases nine times, and vice versa. It follows from the second law of dynamics that the acceleration that a body receives under the action of a force is inversely proportional to the body's mass. But the acceleration of gravity does not depend on body weight. This is possible only if the force with which the Earth attracts the body changes in proportion to the body's mass. According to the third law, the forces with which the bodies interact are equal. If the force acting on one body is proportional to the mass of this body, then the force equal to it acting on the second body is obviously proportional to the mass of the second body. But the forces acting on both bodies are equal, therefore, they are proportional to the mass of the first and second bodies. Newton calculated the ratio of the radius of the Moon's orbit to the radius of the Earth. The ratio was 60. And the ratio of the acceleration of gravity on Earth to the centripetal acceleration with which the Moon revolves around the Earth was 3600. Therefore, the acceleration is inversely proportional to the square of the distance between the bodies. According to the second law, force and acceleration are directly related, therefore, force is inversely proportional to the square of the distance between the bodies.
For the first time the gravitational constant was measured by the English physicist G. Cavendish in 1788 using an instrument called a torsion balance. G. Cavendish fixed two small lead balls (5 cm in diameter and 775 g each) at opposite ends of a two-meter rod. The rod was suspended from a thin wire. Two large lead balls (20 cm in diameter and 45.5 kg) were brought close to the small ones. The forces of attraction from the side of the large balls made the small ones move, while the wire twisted. The degree of twisting was a measure of the force acting between the balls. The experiment showed that gravitational G = 6.67 * 10-11 N * m2 / kg2.
Newton's theory of gravitation has won one brilliant victory after another. She explained with a high degree of accuracy the features of planetary orbits found by Kepler. She managed to measure the masses of the planets, to reveal the mysteries of the motion of comets, the secrets of the tides. But, perhaps, the greatest triumph was the prediction of discoveries that had not yet been made - the appearance of Halley's comet at the time specified by the theory, the discovery of planets and stars unknown to astronomers.
Accurate observations of the motion of the planet Uranus have shown that this motion does not strictly obey Newton's law. This means that there is some as yet unknown reason causing the planet to deviate from the path predetermined by the theory. According to the calculations of the French scientist Le Verrier, it turned out that somewhere in the depths of space, beyond Uranus, there must be another planet. And as soon as the telescope was directed to the point indicated by the calculations (this happened in 1846), the desired star immediately shone in front of the astronomer's seeking gaze! This is how Neptune was discovered, followed by Pluto.
No less brilliant was the solution to the Sirius riddle, which has long tormented astronomers. Sirius is the brightest star in our sky, it is located in the constellation Big Dog, at a distance of 8.8 light years from Earth. More than 100 years ago, it was noticed that Sirius does not move in a straight line, like almost all other stars, but somehow strangely, along a wavy curve. With the help of Newton's theory of gravitation, it was established that the "secret" of Sirius's motion is connected with the fact that it is not a simple, but a double star. Indeed, in this case, the center of mass of both stars would move, as expected, in a straight line, and Sirius, as a result of revolution around this center, would deviate one way from a straight line, then another, writing out a wavy curve visible in the sky. It was only 18 years after the theoretical prediction that a companion star, dubbed Sirius-B, was actually discovered in a telescope. This happened in 1862.
The existence of universal gravitation has been proven. But what is this force - universal gravitation? Does she not manifest herself on Earth? And Newton answered this question, linking in the same mathematical formula not only the motion of the planets, but also the fall of a stone on the earth's surface. Newton solved this problem at the age of twenty-four. At sea level and on the tops of the highest mountains - everywhere, bodies fall due to gravity. "So, maybe the phenomenon of gravity extends to the moon itself?" - thought Newton and began to verify his assumption. If so, then the motion of the moon can be compared to the flight of a nucleus ejected from a cannon.
The higher the speed of the nucleus, the more smooth its trajectory becomes and the nucleus flies farther and farther. Mathematical calculations showed an amazing thing: if the flight speed of the nucleus reached 7906 meters per second, then the curvature of the trajectory of the nucleus would become the same as the curvature of the earth's surface. Isn't the Moon, like this core, also held back by the force of gravity, which does not allow it to recede in a straight line into world space? This is what Newton decided to check. To do this, it was necessary to calculate how great the force of gravity is at the distance of the Moon from the Earth. The action of gravity at the distance of the moon turned out to be the same as the action of universal gravitation. This means that the force of gravity and the universal gravitation are one and the same force.
It seemed that Newton's theory was unshakable for centuries. Indeed, even now, when science is storming space, the movement of satellites, space rockets is calculated with great accuracy using Newton's theory.
Any body can become a satellite if it is told at a given altitude the required speed perpendicular to the Earth's radius.
The speed that must be imparted to the body in order for it to become a satellite of the planet is called the first cosmic speed.
Yet at the heart of this theory were its fundamental flaws. No matter how accurate the theory is, it is unable to answer the fatal question: what is the origin of the force of gravity, what is its nature? The author Isaac Newton himself admitted his impotence, saying: "I could not deduce the cause of the properties of the force of gravity from phenomena, but I do not invent hypotheses."
What Newton failed was done by another great scientist - Albert Einstein. In 1916, he published his famous general theory of relativity, containing radically new ideas about the nature of gravity. On its basis, he created a new picture of the universe. Einstein's theory "absorbed" Newton's law, having managed to go immeasurably further, she explained gravity not by some special force acting from massive bodies - the Earth, the Sun, etc., but by the peculiarities of space near such bodies.
For the first time, science was able to explain the nature, the origin of gravitation. Newton fully admitted the abstract theoretical possibility of the existence of space, in which there is no matter at all and gravitation is indeed absent even theoretically, so that there free motion by inertia is actually rectilinear and uniform. Einstein believed that this is impossible in principle. According to his theory, neither space nor time simply exists without matter. Once, when asked by a reporter about what, in the very short form, the essence of the general theory of relativity, Einstein replied: “Earlier it was believed that if all matter disappeared from the Universe, then space and time would be preserved. The theory of relativity asserts that space and time would disappear along with matter. " Space in a gravitational field, as Einstein said, is "curved" - it is this curvature that is a manifestation of gravitation, and there is gravity itself.
III. Reflective-evaluative stage of the lesson.
Summarizing.
Mutual evaluation of work in the lesson.
List of used literature and sources.
1. Textbook "Physics Grade 10. A basic level of", NS. Purysheva, N.E. Vazheevskaya, D.A. Isaev, Moscow, Bustard, 2010
2. Physics. Grade 10. Myakishev G.Ya., Bukhovtsev B.B., Sotskiy N.N. M .: Education, 2008
3. V.A. Volkov Lesson development in physics. 9 grade. Moscow "VAKO", 2005
Related educational materials:
Slide 1
Solving problems. Gravitational forces. 9-10 grade.Slide 2
Does the force of attraction to the Sun act on a person? How to explain the occurrence of ebb and flow in the ocean? Explain the physical meaning of the gravitational constant? Frontal student survey:
Slide 3
How many times will the force of attraction between bodies change with an increase in the distance between them by 5 times? A. Will increase 5 times; B. Will decrease by 5 times; C. Will decrease 25 times. 2. How many times will the force of attraction between bodies change with a decrease in the mass of each of the bodies by 2 times? A. Will increase 2 times; B. Will decrease by 4 times; C. Will decrease by 4 times. Complete the task:
Slide 4
3. How many times will the force of attraction between bodies change with an increase in the distance between them by 2 times and an increase in the mass of one of them by 4 times? A. Increase by 8 times B. Will not change C. Decrease by 2 times How many times will the force of attraction between bodies change with a 2-fold decrease in the mass of one of the bodies and a 2-fold increase in the distance between them? A. Increase by 2 times B. Decrease by 4 times C. Decrease by 8 times
Slide 5
Solve the problem: 1. A force of 720 N acts on an astronaut on the Earth's surface. What gravitational force will act on the same astronaut in a spacecraft located at a distance of two Earth radii from the Earth's surface? A) 180 N B) 80 N C) 360 N D) 240 N
Slide 6
Solve the problem: 2. Two bodies weighing 103 kg and 2 · 103 kg are at a distance R from each other and are attracted with a force F. What is the force of attraction of bodies weighing 2 · 103 kg and 4 · 103 kg, located at the same distance R ? A) F B) 2F C) 4F D) 8F
Slide 7
Solve the problem: 3. On the surface of the Earth, a gravity force of 1000 N acts on the astronaut in a spacesuit. On the surface of the planet, the radius is 2 times less than that of the Earth and the mass is 2 times less than the mass of the Earth, the force of gravity acting on this astronaut will be equal to: A) 500 N B) 1000 N C) 2000 N D) 4000 N
Slide 8
Solve the problem: 4. Which of the following statements are correct? A) The force of universal gravitation keeps the planets in their orbits around the Sun B) The force of universal gravitation will change if the density of one of the attracting bodies changes C) In free fall, a heavier body will fall faster than a lighter one if dropped from the same height D) If the body is not affected by gravity, then the body is in a state of weightlessness
9-10 grade.
Does the force of attraction to the Sun act on a person?
How to explain the occurrence of ebb and flow in the ocean?
Explain the physical meaning of the gravitational constant?
How many times will the force of attraction between bodies change with an increase in the distance between them by 5 times?A.Will increase 5 times;
B.Will decrease by 5 times;
C.Will decrease 25 times.
2. How many times will the force of attraction between bodies change with a decrease in the mass of each body by 2 times?A. Will increase 2 times;
B. Will decrease by 4 times;
C. It will decrease by 4 times.
3. How many times will the force of attraction between bodies change with an increase in the distance between them by 2 times and an increase in the mass of one of them by 4 times? A... Will increase 8 times
B... Will not change
C... Will decrease by 2 times
How many times will the force of attraction between bodies change with a 2-fold decrease in the mass of one of the bodies and a 2-fold increase in the distance between them?
A... Will increase 2 times
B... Will decrease by 4 times
C... Will decrease by 8 times
1. A force of 720 N acts on an astronaut on the Earth's surface. What gravitational force will act on the same astronaut in a spacecraft located at a distance of two Earth radii from the Earth's surface?
A) 180 N B) 80 N C) 360 N D) 240 N
2. Two bodies weighing 103 kg and 2 · 103 kg are at a distance R from each other and are attracted with a force F. What is the force of attraction for bodies weighing 2 · 103 kg and 4 · 103 kg, located at the same distance R?
A) F B) 2F C) 4F D) 8F
3. On the surface of the Earth, a gravity force of 1000 N acts on an astronaut in a spacesuit. On the surface of a planet with a radius 2 times less than that of the Earth and a mass 2 times less than the mass of the Earth, the force of gravity acting on this astronaut will be equal.
