What is the relative value of the path or displacement. Trajectory. Way. Moving. What is displacement in physics definition

Class: 9

Lesson objectives:

• Educational:
  - to introduce the concepts of "displacement", "path", "trajectory".
• Developing:
  - to develop logical thinking, correct physical speech, use the appropriate terminology.
• Educational:
  - to achieve high class activity, attention, concentration of students.

Equipment:

• plastic bottle with a capacity of 0.33 l with water and with a scale;
• medical vial with a capacity of 10 ml (or a small test tube) with a scale.

Demonstrations: Determination of movement and distance traveled.

During the classes

1. Actualization of knowledge.

- Hello guys! Sit down! Today we will continue to study the topic “Laws of interaction and motion of bodies” and in the lesson we will get acquainted with three new concepts (terms) related to this topic. In the meantime, let's check your homework for this lesson.

2. Checking homework.

Before the lesson, one student writes on the blackboard the solution to the following homework assignment:

Two students are given cards with individual assignments, which are completed during the oral check of exercise. 1 page 9 of the textbook.

1. Which coordinate system (one-dimensional, two-dimensional, three-dimensional) should be chosen to determine the position of bodies:

a) tractor in the field;
b) a helicopter in the sky;
c) train
d) a chess piece on the board.

2. An expression is given: S \u003d υ 0 · t + (a · t 2) / 2, express: a, υ 0

1. What coordinate system (one-dimensional, two-dimensional, three-dimensional) should be chosen to determine the position of such bodies:

a) a chandelier in the room;
b) an elevator;
c) submarine;
d) an airplane on the runway.

2. An expression is given: S \u003d (υ 2 - υ 0 2) / 2 · a, express: υ 2, υ 0 2.

3. Study of new theoretical material.

Changes in the coordinates of the body are associated with the quantity introduced to describe the motion - MOVEMENT.

The movement of a body (material point) is a vector that connects the initial position of the body with its subsequent position.

Moving is usually denoted by a letter. In SI, displacement is measured in meters (m).

- [m] - meter.

Displacement - magnitude vector, those. besides the numerical value, it also has a direction. The vector quantity is depicted as segmentthat starts at some point and ends with a point indicating the direction. Such an arrow segment is called vector.

- vector drawn from point M to M 1

To know the displacement vector means to know its direction and module. The modulus of a vector is a scalar, i.e. numerical value. Knowing the initial position and the vector of movement of the body, you can determine where the body is.

In the process of movement, a material point occupies different positions in space relative to the selected frame of reference. In this case, a moving point “describes” some line in space. Sometimes this line is visible - for example, an airplane flying high can leave a trail in the sky. A more familiar example is the trail of a piece of chalk on a blackboard.

The imaginary line in space along which the body moves is called TRAJECTORY body movements.

The trajectory of a body is a continuous line that describes a moving body (considered as a material point) in relation to the selected frame of reference.

The movement in which all points body moving along the same trajectoriesis called progressive.

Very often the trajectory is an invisible line. Trajectory moving point can be straightor crookedline. According to the shape of the trajectory motion it happens straightforward and curvilinear.

The length of the trajectory is WAY... The path is a scalar and denoted by the letter l. The path increases if the body is moving. And it remains unchanged if the body is at rest. Thus, the path cannot decrease over time.

The displacement module and the path can coincide in value only if the body moves along a straight line in the same direction.

What is the difference between a path and a movement? These two concepts are often confused, although in reality they are very different from each other. Consider these differences: ( Appendix 3) (distributed as cards to each student)

1. The path is a scalar value and is characterized only by a numeric value.
2. Displacement is a vector quantity and is characterized by both a numerical value (modulus) and a direction.
3. When the body moves, the path can only increase, and the displacement modulus can both increase and decrease.
4. If the body has returned to the starting point, its movement is zero, and the path is not zero.

	Way	Moving
Definition	The length of the trajectory described by the body for a certain time	A vector connecting the initial position of the body with its subsequent position
Designation	l [m]	S [m]
The nature of physical quantities	Scalar, i.e. defined by numeric value only	Vector, i.e. determined by the numerical value (modulus) and direction
Need for introduction	Knowing the initial position of the body and the path l traveled during the time interval t, it is impossible to determine the position of the body at a given time t	Knowing the initial position of the body and S for the time interval t, the position of the body at a given time t is uniquely determined
	l \u003d S in the case of rectilinear movement without returns

4. Demonstration of experience (students perform independently in their places at their desks, the teacher together with the students performs a demonstration of this experience)

1. Fill a plastic bottle with a scale with water up to the neck.
2. Fill the bottle with a scale with water to 1/5 of its volume.
3. Tilt the bottle so that the water comes to the neck, but does not flow out of the bottle.
4. Quickly dip the bottle of water into the bottle (without plugging it) so that the neck of the bottle enters the water in the bottle. The bottle floats on the surface of the water in the bottle. Part of the water will pour out of the bottle.
5. Screw on the bottle cap.
6. While squeezing the sides of the bottle, lower the float to the bottom of the bottle.

1. By releasing the pressure on the walls of the bottle, bring the float up. Determine the path and movement of the float: ________________________________________________________
2. Lower the float to the bottom of the bottle. Determine the path and movement of the float: ______________________________________________________________________________
3. Make the float float and sink. What is the path and movement of the float in this case? _______________________________________________________________________________________

5. Exercises and Review Questions.

1. Do we pay for the way or travel when traveling by taxi? (Way)
2. The ball fell from a height of 3 m, bounced off the floor and was caught at a height of 1 m. Find the path and movement of the ball. (Path - 4 m, travel - 2 m.)

6. Lesson summary.

Lesson repetition:

- moving;
- trajectory;
- way.

7. Homework.

§ 2 of the textbook, questions after the paragraph, exercise 2 (page 12) of the textbook, repeat the lesson experience at home.

List of references

1. Peryshkin A.V., Gutnik E.M.... Physics. 9th grade: textbook for general education institutions - 9th ed., Stereotype. - M .: Bustard, 2005.

Displacement, shift, movement, migration, movement, rearrangement, regrouping, transfer, transportation, transition, move, transfer, travel; shifting, moving, telekinesis, epeirophoresis, relining, rolling, rolling, ... ... Synonym dictionary

MOVEMENT, displacement, cf. (book). 1. Action according to Ch. move move. Moving through the service. 2. Action and condition according to Ch. move move. Moving layers of the earth's crust. Ushakov's explanatory dictionary. D.N. Ushakov. 1935 1940 ... Ushakov's Explanatory Dictionary

In mechanics, a vector connecting the positions of a moving point at the beginning and at the end of a certain period of time; the vector P. is directed along the chord of the trajectory of the point. Physical encyclopedic dictionary. M .: Soviet encyclopedia. Chief editor A. M. ... ... Physical encyclopedia

MOVE, still, eat; haunted (yeon, yea); Sov., who what. Place, transfer to another place. P. scenery. P. brigade to another site. Displaced persons (persons forcibly displaced from their country). Ozhegov's Explanatory Dictionary. SI ... ... Ozhegov's Explanatory Dictionary

- (relocation) Relocation of an office, enterprise, etc. to another place. It is often caused by mergers and acquisitions. Occasionally, employees receive a relocation allowance to encourage them to stay in this ... ... Business Glossary

moving - - Topics telecommunications, basic concepts EN redeployment ... Technical translator's guide

Moving, - Displacement, mm, the amount of change in the position of any point of a window block element (as a rule, a mullion of a box or vertical bars of sashes) in the direction normal to the plane of the product under the influence of wind load. Source: GOST ... ...

moving - Migration of material in the form of a solution or suspension from one soil horizon to another ... Geography Dictionary

moving - 3.14 transfer (in relation to storage location) change in the storage location of a document Source: GOST R ISO 15489 1 2007: System of standards for information ... Dictionary-reference book of terms of normative and technical documentation

moving - ▲ change of position, motionless movement in space; change of position in space; a shape transformation that preserves the distance between the shape's points; movement to another place. movement. translational movement ... ... Ideographic Dictionary of the Russian Language

Books

• GESNm 81-03-40-2001. Part 40. Additional movement of equipment and material resources,. State estimated standards. State elemental estimated standards for the installation of equipment (hereinafter referred to as HESNm) are intended to determine the need for resources (labor costs of workers, ...
• Moving people and goods in near-earth space by means of technical ferrographization, R. A. Sizov. This publication is the second applied edition to the books of R. A. Sizov "Matter, Antimatter and Energy Medium - Physical Triad of the Real World", in which, on the basis of the discovered ...

If we take into account the physical processes in the everyday sphere, then many of them seem to be very nice. Therefore, the concepts of path and movement are perceived as one and the same, the only difference is that the first is a description of the action, and the second is the result of the action. But if you turn to information sources for clarification, you can immediately find a significant difference between these operations.

What is the path?

A path is a movement as a result of which there is a change in the location of an object or person. This value is scalar, therefore it has no direction, but it can be used to determine the distance traveled.

The path can be executed in the following ways:

• In a straight line.
• Curvilinear.
• Round.
• Other methods are possible (for example, a zigzag path).

The path can never be negative and decrease over time. The path is measured in meters. Most often, in physics, the letter is used to indicate the path S, in rare cases, they use the letter L. With the help of the path, one cannot foresee where the object we need will be at a certain moment in time.

Move features

Displacement is the difference between the starting and ending point of a person or object in space after a certain path has been overcome.

The displacement value is always positive and also has a clear direction.

The coincidence between the displacement and the path is possible only if the path was carried out in a straight line, and the direction did not change.

With the help of movement, you can calculate where a person or object was at a certain point in time.

The letter S is used to denote displacement, but since displacement is a vector quantity, an arrow → is placed above this letter, which indicates that displacement is a vector. Unfortunately, adding to the confusion between path and displacement is the fact that both concepts can also be denoted by the letter L.

What do the concepts of path and travel have in common?

Despite the fact that the path and movement are completely different concepts, there are certain elements that contribute to the fact that the concepts are confused:

1. The path and displacement can always only be positive values.
2. The same letter L can be used to indicate the path and movement.

Even considering the fact that these concepts have only two elements in common, their meaning is so great that it makes many people confused. Students especially have problems while studying physics.

What are the main differences between path and travel?

These concepts have a number of differences that will always help determine what value is in front of you, a path or movement:

1. The path is the primary concept, and the movement is secondary. For example, movement determines the difference between the starting and ending point of a person's location in space after overcoming a certain path. Accordingly, you cannot get the amount of movement without using the path initially.
2. The beginning of the movement plays a huge role for the path, and the beginning of the movement is absolutely unnecessary to determine the movement.
3. The main difference between these values \u200b\u200bis that the path has no direction, but the movement has one. For example, the path is carried out only directly - forward, and movement allows movement backward.
4. Moreover, the concepts differ in appearance. The path refers to a scalar, and the move refers to a vector.
5. Calculus method. For example, the path is calculated using the total distance traveled, and movement, in turn, is calculated by changing the location of the object in space.
6. The path can never be equal to zero, and a value equal to zero is allowed in the movement.

Having studied these differences, you can immediately understand what is the difference between the concepts of path and movement, and you will never again be confused.

Difference between path and move in examples

In order to quickly understand the difference between a path and a move, you can use certain examples:

1. The car moved 2 meters forward and 2 meters back. The path is the sum of the total distance traveled, respectively, it is 4 meters. And displacement is the start and end point, so in this case it is zero.
2. In addition, the difference between a path and a movement can be seen from our own experience. You need to stand at the start of a 400-meter treadmill and run two laps (the second lap will end at the starting point). The result is that the path is 800 meters (400 + 400), and the displacement is 0, since the start and end points are the same.
3. The ball thrown upwards reached a height of 15 meters and then fell to the ground. In this case, the path will be 30 meters, since 15 meters up and 15 meters down are added. And the movement will be equal to 0, due to the fact that the ball has returned to its original position.

At first glance, movement and path are similar concepts. However, in physics, there are key differences between displacement and path, although both concepts are associated with a change in the position of a body in space and are often (usually in rectilinear motion) numerically equal to each other.

To understand the differences between displacement and path, let us first give them the definitions that physics gives them.

Body movement - this is directed line segment (vector)whose beginning coincides with the starting position of the body and the end coincides with the ending position of the body.

Body path - this is distancethat the body has passed in a certain period of time.

Let's imagine that you have become at your entrance to a certain point. We walked around the house and returned to the starting point. So: your movement will be equal to zero, and the path will not. The path will be equal to the length of the curve (for example, 150 m), along which you walked around the house.

However, back to the coordinate system. Let a point body move rectilinearly from point A with coordinate x 0 \u003d 0 m to point B with coordinate x 1 \u003d 10 m.The movement of the body in this case will be 10 m. body way.

If the body moved rectilinearly from the initial (A) point with the coordinate x 0 \u003d 5 m, to the end point (B) with the coordinate x 1 \u003d 0, then its displacement will be -5 m, and the path 5 m.

The displacement is found as a difference, where the initial coordinate is subtracted from the final coordinate. If the end coordinate is less than the start coordinate, that is, the body moved in the opposite direction with respect to the positive direction of the X axis, then the displacement will be negative.

Since displacement can have both positive and negative values, displacement is a vector quantity. In contrast, the path is always a positive or zero value (the path is a scalar), since the distance cannot be negative in principle.

Let's take another example. The body moved rectilinearly from point A (x 0 \u003d 2 m) to point B (x 1 \u003d 8 m), then also rectilinearly moved from B to point C with coordinate x 2 \u003d 5 m.What are the common paths (A → B → C) done by this body and its total displacement?

Initially, the body was at a point with a coordinate of 2 m, at the end of its movement it turned out to be at a point with a coordinate of 5 m. Thus, the movement of the body was 5 - 2 \u003d 3 (m). It is also possible to calculate the total displacement as the sum of two displacements (vectors). The movement from A to B was 8 - 2 \u003d 6 (m). Moving from point B to C was 5 - 8 \u003d -3 (m). Adding both displacements, we get 6 + (-3) \u003d 3 (m).

The total path is calculated by adding the two distances traveled by the body. The distance from point A to B is 6 m, and from B to C the body has traveled 3 m.Total we get 9 m.

Thus, in this problem, the path and movement of the body differ from each other.

The problem considered is not entirely correct, since it is necessary to indicate the moments of time at which the body is at certain points. If x 0 corresponds to the moment of time t 0 \u003d 0 (the moment of the beginning of observations), then let for example x 1 correspond to t 1 \u003d 3 s, and x 2 corresponds to t 2 \u003d 5 s. That is, the time interval between t 0 and t 1 is 3 s, and between t 0 and t 2 is 5 s. In this case, it turns out that the body's path in a time interval of 3 seconds was 6 meters, and in an interval of 5 seconds - 9 meters.

Time appears in the definition of the path. In contrast, time does not really matter for moving.