What is movement? In physics, this concept means an action leading to a change in the position of the body in space over a certain period of time relative to a certain reference point. Let us consider in more detail the basic physical quantities and laws that describe the motion of bodies.
The concept of coordinate system and material point
Before proceeding to a discussion of the question of what movement is, it is necessary to define some basic concepts.
One of these concepts is the material point. In physics, cases are often considered when the shape and size of the body are unimportant, since they are negligible in comparison with the distances traveled by them. When the geometrical dimensions of the object in question are unimportant to solve the problem, they say that it is a material point.
Another concept important for describing motion is the coordinate system, under which they mean a set of numbers and axes that allow us to uniquely determine the position of a material point in space.
Values describing the movement
The branch of physics that studies the behavior of moving objects is called kinematics. In kinematics, the movements of a material point are often considered. Knowing what a movement is, you should list the main elements that are directly related to it:
- A trajectory is an imaginary line in space along which a body moves. It can be rectilinear, parabolic, elliptic and so on.
- The path (S) is the distance that a material point travels during its movement. The path in the SI system is measured in meters (m).
- Speed (v) is a physical quantity that determines how much distance a material point travels per unit of time. Measured in meters per second (m / s).
- Acceleration (a) is a quantity that describes the change in the velocity of a material point. It is expressed in SI in m / s 2 .
- Travel time (t).
The laws of motion. Their mathematical formulation
Having understood what movement is and what quantities determine it, we can write down the expression for the path: S = v * t. The motion described by this equation is called uniform rectilinear. If the speed of the material point changes, then we should write the formula for the path as follows: S = v 0 * t + a * t 2/2, here the speed v 0 is called the initial one (at time t = 0). At any other instant of time t, the speed of the material point is determined by the formula: v = v 0 + a * t. This type of movement is called rectilinear uniformly accelerated (equally slow).
The formulas considered are quite simple, since they are used for rectilinear motion. In nature, moving objects along curved paths are often found. In these cases, it is important to take into account the vector properties of speed and acceleration. For example, one of the simple movements along a curved path is the movement of a material point in a circle. In this case, the concept of centripetal acceleration is introduced, which determines the change not in the speed module, but in its direction. This acceleration is calculated by the formula: a = v 2 / R, where R is the radius of the circle.
Motion examples
Having dealt with the question of what movement is, it is useful to illustrate some examples in everyday life and nature.
Moving a car along the roadway, riding a bicycle, jumping a ball on a lawn, sailing a ship at sea, flying a plane in the sky, lowering a skier on a snowy mountainside, running a sprinter at sports competitions are all examples of moving objects in everyday life.
The rotation of the planets around the Sun, the fall of a stone on the earth, the vibration of leaves and tree branches under the influence of wind, the movement of cells that make up the tissues of living organisms, and finally, the thermal chaotic movement of atoms and molecules are examples of the movement of natural objects.
If you approach the issue from a philosophical point of view, it should be said that movement is a fundamental property of being, since everything that exists around us is in constant movement and change.