What is mechanical movement and how is it characterized? What parameters are introduced to understand this type of movement? What terms at the same time most often operate? In this article, we will answer these questions, consider the mechanical movement from different points of view, give examples and deal with solving problems from the physics of relevant topics.
Even at school, we are taught that mechanical movement is a change in body position at any time relative to other bodies of the system. In fact, it is. Let's take an ordinary house in which we are, for zero coordinate system. Imagine visually that the house will be the origin of coordinates, and the abscissa axis and the ordinate axis will extend from it in all directions.
In this case, our movement within the house, as well as outside it, will clearly demonstrate the mechanical movement of the body in the frame of reference. Imagine that a point moves along a coordinate system, at each moment of time changing its coordinate with respect to both the x-axis and the y-axis. Everything will be simple and clear.
Characteristic of mechanical movement
What could be this type of movement? We will not go deep into the wilds of physics. Consider the simplest cases where the movement of a material point occurs. It is subdivided into rectilinear motion, and also into curvilinear motion. In principle, everything should be clear from the title, but let's talk about this more specifically just in case.
Rectilinear movement of a material point will be called such movement, which is carried out along a trajectory, having the form of a straight line. Well, for example, the car goes directly under the road, which has no turns. Or on the site of a similar road. This will be a rectilinear motion. In this case, it can be uniform or uniformly accelerated.
A curvilinear motion of a material point will be called such a motion, which is carried out along a trajectory that does not have the form of a straight line. The trajectory can be a broken line, as well as a closed line. That is a circular trajectory, ellipsoid and so on.
Mechanical movement of the population
This kind of movement has almost absolutely nothing to do with physics. Although, depending on what point of view we perceive it. What, in general, is called the mechanical movement of the population? They are called the relocation of individuals, which occurs as a result of migration processes. This can be both external and internal migration. The duration of the mechanical movement of the population is divided into permanent and temporary (plus pendulum and seasonal).
If we consider this process from a physical point of view, we can say only one thing: this movement will be perfect to show the movement of material points in the reference system associated with our planet Earth.
Uniform mechanical movement
As the name implies, this is a type of movement in which the speed of a body has a certain value, which is kept constant in absolute value. In other words, the speed of the body, which moves uniformly, does not change. In real life, we can hardly notice ideal examples of uniform mechanical motion. You can quite reasonably argue, they say, you can go by car at a speed of 60 kilometers per hour. Yes, of course, the vehicle speedometer can demonstrate a similar value, but this does not mean that in fact the car’s speed will be exactly sixty kilometers per hour.
What is this about? As we know, firstly, all measuring instruments have a certain error. Rulers, scales, mechanical and electronic devices - they all have a certain error, inaccuracy. You can see this for yourself by taking a dozen lines and applying them one to another. After this, you will be able to notice some discrepancies between the millimeter marks and their application.
The same goes for the speedometer. He has a certain error. For instruments, the inaccuracy is numerically equal to half the price of division. In cars, the speedometer inaccuracy will be 10 kilometers per hour. That is why at a certain moment it is impossible to say for sure that we are moving with one speed or another. The second factor that will contribute to inaccuracy will be the forces acting on the car. But the forces are inextricably linked with acceleration, so on this topic we will talk later.
Very often, uniform motion is found in problems of a mathematical nature, rather than physical. There, motorcyclists, trucks and cars move at the same speed, equal in magnitude at different points in time.
Uniformly accelerated motion
How to find out that the motion is uniformly accelerated? Usually in problems information about this is submitted directly. That is, there is either a numerical indication of acceleration, or parameters (time, change in speed, distance) are given, which allow us to determine the acceleration. It should be noted that acceleration is a vector quantity. So, it can be not only positive, but also negative. In the first case, we will observe the acceleration of the body, in the second - its inhibition.
But it happens that information about the type of movement is taught to the student in a somewhat secretive form, if you can call it that. For example, it says that nothing acts on a body or the sum of all forces is zero. Well, in this case, you need to clearly understand that we are talking about uniform motion or rest of the body in a certain coordinate system. If you remember Newton's second law (which says that the sum of all forces is nothing but the product of body mass and acceleration, reported by the action of the corresponding forces), you will easily notice one interesting thing: if the sum of forces is zero, then the product of mass and acceleration will also be zero.
But the mass is we have a constant, and it is not a priori to be zero. In this case, it would be logical to conclude that in the absence of external forces (or compensated) acceleration of the body is missing. So, it is either at rest or moving with constant speed.
Sometimes there is an approach in the scientific literature according to which light formulas are first given, and then, taking into account certain factors, they become more complicated. We will do the opposite, namely, we will first consider a uniformly accelerated motion. The formula according to which the distance traveled is calculated as follows: S = V0t + at ^ 2/2. Here V0 is the initial velocity of the body, a is the acceleration (maybe negative, then the + sign will change to - in the formula), and t is the time elapsed from the beginning of the movement to the stopping of the body.
Uniform motion formula
If we talk about uniform motion, then we recall that in this case the acceleration is zero (a = 0). Substitute zero in the formula and get: S = V0t. But after all, the speed throughout the entire section of the path is constant, if we talk roughly, that is, we have to neglect the forces acting on the body. Which, by the way, is practiced everywhere in kinematics, since kinematics does not study the causes of motion, this is what dynamics do. So, if the speed throughout the entire section of the path is constant, then its initial value coincides with any intermediate, as well as final. Therefore, the distance formula will look like this: S = Vt. That's all.