What is movement? In physics, this concept means an action that leads to a change in the position of a 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 movement of bodies.
The concept of a coordinate system and a material point
Before proceeding to the analysis of the question of what movement is, it is necessary to define some basic concepts.
One of these concepts is a material point. In physics, cases are often considered when the shape and dimensions of the body are unimportant, since they are negligible in comparison with the distances traveled by it. When the geometric dimensions of the object under consideration are not important for solving the problem, they say that it is a material point.
Another important concept for describing motion is the coordinate system, under which a set of numbers and axes is supposed to unambiguously determine the position of a material point in space.
Quantities describing movement
The section of physics that studies the behavior of moving objects is called kinematics. In kinematics, the motions of a material point are often considered. Knowing what movement is, one should list the main elements that are directly related to it:
- Trajectory - an imaginary line in space along which the body moves. It can be straight, parabolic, elliptical, and so on.
- Path (S) - this is the distance that a material point passes in the process of its movement. The SI path is measured in meters (m).
- Speed (v) - a physical quantity that determines how far a material point travels per unit of time. Measured in meters per second (m/s).
- Acceleration (a) - a value that describes the change in the speed of a material point. It is expressed in SI in m/c2.
- Movement time (t).
Laws of motion. Their mathematical formulation
Having figured out what movement is and what quantities determine it, we can write an expression for the path: S=vt. The motion described by this equation is called uniform rectilinear. If the speed of the material point changes, then the formula for the path should be written as follows: S=v0t+at2/2, here the speed v0 is called initial (at time t=0). At any other time t, the velocity of a material point is determined by the formula: v=v0 + at. This type of motion is called rectilinear uniformly accelerated.(evenly slow).
The considered formulas are quite simple, since they are used for rectilinear motion. In nature, objects often move along curvilinear trajectories. In these cases, it is important to take into account the vector properties of velocity and acceleration. For example, one of the simple movements along a curved path is the movement of a material point along a circle. In this case, the concept of centripetal acceleration is introduced, which determines the change not in the velocity modulus, but in its direction. This acceleration is calculated by the formula: a=v2/R, where R is the radius of the circle.
Examples of movement
Having de alt with the question of what movement is, it is useful for clarity to give some examples in everyday life and nature.
Moving a car on a roadway, riding a bicycle, jumping a ball on a lawn, floating a ship in the sea, flying an airplane in the sky, a skier descending a snowy mountainside, a sprinter running in a sports competition are all examples of the movement of objects in everyday life.
The rotation of the planets around the Sun, the fall of a stone to the ground, the oscillation of the leaves and branches of trees under the influence of the 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, then it should be said that movement is a fundamental property of being, since everything that exists around us,is in constant motion and change.
