Kinematics is one of the important sections of mechanics, which considers the laws of movement of bodies in space (the causes of motion are studied by dynamics). In this article, we will consider one of the main quantities of kinematics, we will answer the question: "What is a path in physics?"
The concept of the path
What is a path in physics? This is a value equal to the length of the segment in space, which the body under study has overcome in the course of its movement. To calculate the path, it is necessary to know not only the initial and final positions of the body, but also the trajectory of its movement. The question of what a path is in physics can be answered differently. This value is understood as the length of the trajectory, that is, the imaginary line along which the body moved.
Different characters are used to indicate the path. So, if we are talking about one-dimensional movement, then we can use the symbol Δx, where Δ means a change in the x coordinate. In addition to this symbol, the letters s, l and h are often used to designate the quantity under consideration, the latter two meaning length and height, respectively. SoThus, in kinematics, the letter s can be found most often to designate a path.
If it is known that the body moves in a straight line in three-dimensional space, and the coordinates of its initial position are known (x0; y0; z0) and final (x1; y1; z1), then the path can be determined by the formula:
s=√((x1 - x0)2 + (y 1 - y0)2 + (z1 - z 0)2)
Kinematic formulas
Having considered how the path is designated in physics and what this value is, we present a couple of kinematic formulas that are used to calculate the studied motion characteristic. These are the following formulas:
s=v × t;
s=v0 × t ± a × t2 / 2
Here the first expression corresponds to the situation when the body moves uniformly in a straight line with a speed v during the time t. The second expression is valid for uniformly accelerated movement, where the symbols v0 and a denote the initial speed and acceleration, respectively. The plus sign should be used if the body is accelerating, and the minus sign if it is decelerating.
Example problem
Having analyzed what a path is in physics, let's solve the following problem. A boat with a speed of 13 km / h moves against the current of the river for 1.5 hours from one point to another. How far does the boat travel if the speed of the river is 3km/h?
This is a classic problem of applying the formula for the uniform motion of a body. The complexity of the task is only to determine the actual speed of the boat. Since its movement occurs against the current, it will be equal to the difference: 13 - 3 \u003d 10 km / h. Now it remains to substitute the known values in the formula for s and get the answer:
s=v × t=10 [km/h] × 1.5 [h]=15 km
In path calculation problems, it is necessary to follow the dimensions of the used values of speed, time and acceleration in order to avoid mistakes.
