Presentation of the acceleration of a point when moving in a circle. Presentation in physics on the topic "movement of a body in a circle." Uniform movement of a point along a circle
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Movement in a circle Physics teacher Fedorov Alexander Mikhailovich MOU Kyukyay secondary school Suntarsky ulus Republic of Sakha
In the life around us, we meet with movement in a circle quite often. This is how the clock hands and the gears of their mechanisms move; this is how cars move on convex bridges and on rounded sections of roads; artificial earth satellites move in circular orbits.
The instantaneous velocity of a body moving in a circle is directed tangentially to it at that point. This is easy to observe.
We will study the movement of a point along a circle with a constant modulo speed. It is called uniform circular motion. The speed of a point moving in a circle is often called linear speed. If a point moves along a circle uniformly and in time t passes a path L equal to the length of the arc AB, then the linear velocity (its modulus) is equal to V = L / t A B
Uniform motion in a circle is motion with acceleration, although the modulus of speed does not change. But the direction is constantly changing. Therefore, in this case, the acceleration a should characterize the change in speed in the direction. О v a The acceleration vector a with uniform motion of a point along a circle is directed along the radius to the center of the circle, therefore it is called centripetal. The acceleration module is determined by the formula: a \u003d v 2 /R, Where v is the module of the speed of the point, R is the radius of the circle.
PERIOD OF REVOLUTION The movement of a body in a circle is often characterized not by the speed of movement v, but by the time interval during which the body makes one complete revolution. This value is called the period of revolution. Designate it with the letter T. In calculations, T is expressed in seconds. During the time t, equal to the period T, the body travels a path equal to the circumference: L = 2 R. Therefore, v = L/T=2 R/T. Substituting this expression into the formula for acceleration, we get another expression for it: a= v 2 /R = 4 2 R/T 2 .
Frequency of circulation The movement of a body along a circle can be characterized by another quantity - the number of revolutions along the circle per unit time. It is called the frequency of circulation and is denoted by the Greek letter (nu). The frequency of revolution and the period are related as follows: = 1/T The unit of frequency is 1/s or Hz. Using the concept of frequency, we obtain formulas for speed and acceleration: v = 2R/T = 2R; a \u003d 4 2 R / T 2 \u003d 4 2 2 R.
So, we have studied the movement in a circle: Uniform movement in a circle is movement with acceleration a = v 2 /R. The period of revolution is the period of time during which the body makes one complete revolution. Designate it with the letter T. The frequency of circulation is the number of revolutions in a circle per unit time. It is denoted by the Greek letter (nu). Frequency of revolution and period are related by the following relation: = 1/T Formulas for velocity and acceleration: v = 2R/T = 2R; a \u003d 4 2 R / T 2 \u003d 4 2 2 R.
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On the topic: methodological developments, presentations and notes
Lesson for solving problems on the topic "Dynamics of motion in a circle." In the process of solving problems in groups, mutual learning of students takes place ....
A lesson in learning a new topic using a presentation, videos ....
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In mechanics, examples teach as much as rules. I. Newton
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Riddles of terrible nature hang everywhere in the air.N. Zabolotsky (from the poem "The Mad Wolf")
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A4. The body moves in a circle in a clockwise direction. Which of the vectors shown coincides in direction with the velocity vector of the body at point A? eleven; 2) 2; 3) 3; 4) 4.
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The motion of a body in a circle with a constant modulo speed. Lesson topic:
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Objectives: Repeat the features of curvilinear motion, consider the features of motion in a circle, get acquainted with the concept of centripetal acceleration and centripetal force, period and frequency of rotation, find out the relationship between the quantities.
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Conclusion page 70
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With uniform motion along a circle, the module of its speed does not change. But speed is a vector quantity, and it is characterized not only by a numerical value, but also by direction. With uniform motion in a circle, the direction of the velocity vector changes all the time. Therefore, such uniform motion is accelerated.
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When a body moves uniformly along a circle, the acceleration vector is always perpendicular to the velocity vector, which is directed tangentially to the circle.
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Conclusion page 72
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The rotation period is the time of one revolution around the circumference. Rotation frequency - the number of revolutions per unit of time.
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Kinematics of circular motion
Velocity modulus does not change Velocity modulus changes Linear velocity Angular velocity Acceleration
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Answer: 1 1 2
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d / z § 19 Ex. 18 (1,2) And then a brilliance from on high burst into my mind, Carrying the accomplishment of all his efforts. A. Dante
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Option 1 Option 2 The body moves uniformly in a circle in a clockwise direction counterclockwise How is the acceleration vector directed during such a movement? a) 1; b) 2; at 3 ; d) 4. 2. The car moves with a constant modulo speed along the trajectory of the figure. At which of the indicated points of the trajectory is the centripetal acceleration the minimum maximum? 3. How many times will the centripetal acceleration change if the speed of a material point is increased and decreased by 3 times? a) will increase by 9 times; b) decrease by 9 times; c) will increase by 3 times; d) will decrease by 3 times.
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Option 1 4. The movement of a material point is called curvilinear if a) the trajectory of the movement is a circle; b) its trajectory is a curved line; c) its trajectory is a straight line. 5. A body of mass 1 kg moves at a constant speed of 2 m/s in a circle with a radius of 1 m. Determine the centrifugal force acting on the body. Option 2 4. The movement of a body is called curvilinear if a) all its points move along curved lines; b) some of its points move along curved lines; c) at least one of its points moves along a curved line. 5. A body of mass 2 kg moves at a constant speed of 2 m/s in a circle with a radius of 1 m. Determine the centrifugal force acting on the body.
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Literature Textbooks "Physics -9" A.V. Peryshkin, M.M. Balashov, N.M. Shakhmaev, Laws of physics B.N. Ivanov Unified State Exam assignments Lesson developments in physics V.A. Volkov Multimedia textbook of a new type (physics, basic school 7-9 cells, part 2)
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1 2 Uniform motion along a circle is such a motion in which a material point passes equal arcs of a circle in equal intervals of time. Uniform movement along a circle Solving problems 10 3 4 5 6 7 8 9 Lyakhovich E.Yu.
Orbital period 2 1 10 3 4 5 6 7 8 9 Lyakhovich E.Yu., MBVSOU "VSOSH No. 3", Nizhnekamsk The time of one revolution around the circumference is called the period of rotation T N is the number of revolutions made during the time t . Unit of frequency of revolution - 1 revolution per second (1 s -1) Frequency of revolution
3 2 10 1 4 5 6 7 8 9 Lyakhovich E.Yu.
4 2 10 3 1 5 6 7 8 9 Lyakhovich E.Yu.
5 2 10 3 4 1 6 7 8 9 Lyakhovich E.Yu.
6 2 10 3 4 5 1 7 8 9 Lyakhovich E.Yu., MBVSOU "VSOSH №3", Nizhnekamsk Problem. What is the linear speed of the points on the wheel rim of a steam turbine with a wheel diameter of 1 m and a speed of 300 rpm? Show Solution
7 2 10 3 4 5 6 1 8 9 Lyakhovich E.Yu., MBVSOU "VSOSH №3", Nizhnekamsk Problem. How many times will the centripetal acceleration of a body change if it moves uniformly along a circle of twice the radius with the same angular velocity? Show Solution
8 2 10 3 4 5 6 7 1 9 Lyakhovich E.Yu., MBVSOU "VSOSH №3", Nizhnekamsk Problem. The angular velocity of the fan blades is 20π rad/s. Find the number of revolutions in 30 min. Show Solution
1 Option 2 Option 1. The angular velocity of the fan blades is 20π rad/s. Find the number of revolutions in 30 min. 2. Aircraft propeller speed 1500 rpm. How many revolutions will the propeller make on a path of 90 km at a flight speed of 180 km/h 2 . The locomotive moves at a speed of 60 km/h. How many revolutions per second does its wheels make if their radius is 50 cm? 1 . At the turn, the tram car moves with a constant modulo speed of 5 m/s. What is its centripetal acceleration, if the radius of curvature of the path is 50 m. 9 2 10 3 4 5 6 7 8 1 Lyakhovich E.Yu.
ANSWERS 1 Option 2 Option 1 . 18000.2. 45000 2 . 5.31 1 . 0.5 m/s 2 . 1 2 10 3 4 5 6 7 8 9 Lyakhovich E.Yu., MBVSOU "VSOSH No. 3", Nizhnekamsk
1 2 10 3 4 5 6 7 8 9 Lyakhovich E.Yu., MBVSOU "VSOSH №3", Nizhnekamsk Show solution
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