This topic will be useful not only to high school students, but even adults. In addition, the article will be interesting to parents who want to explain to their children simple things from the natural sciences. Among the very important topics is the speed in physics.
Quite often, students cannot understand the solution of problems, distinguish between the available types of speeds, and it is even more difficult to understand the scientific definitions. Here we look at everything in a more accessible language, so that not only everything is clear, but even interesting. But you still have to remember some things, since technical sciences (physics and mathematics) require you to memorize formulas, units of measure, and, of course, the meanings of the characters in each formula.
Where is it found?
To begin with, we recall that this topic relates to such a section of physics as mechanics, the subsection "Kinematics". In addition, the study of speed does not end there, it will be in the following sections:
- optics,
- vibrations and waves
- thermodynamics,
- quantum physics and so on.
Also, the concept of speed is found in chemistry, biology, geography, computer science. In physics, the theme of "speed" is most often found and is studied in depth.
In addition, this word is used in everyday life by all of us, especially among motorists, drivers of transport equipment. Even experienced chefs sometimes use the phrase, for example, “beat egg whites with a mixer at medium speed”.
What is speed?
Speed in physics is a kinematic quantity. Means the distance that the body travels over a period of time. Suppose a young man moves from home to a store, breaking two hundred meters in one minute. On the contrary, his old grandmother will take the same route in six minutes in small steps. That is, the guy moves much faster than his elderly relative, as he develops speed much more, making very fast long steps.
The same thing should be said about the car: one car goes faster, and the other slower, because the speeds are different. Later we will look at numerous examples related to this concept.
Formula
In a lesson at school, the formula of speed in physics is necessarily considered in order to make it convenient to solve problems.
- V is, respectively, the speed of movement;
- S is the distance that the body travels when moving from one point in space to another;
- t is the travel time.
You should remember the formula, because it will come in handy in the future when solving many problems and not only. For example, you may be wondering how fast you get from home to work or school. But you can know the distance in advance on the map in a smartphone or on a computer, or by the paper version, knowing the scale and having a ruler with you. Next, you note the time before you start moving. Arriving at your destination, see how many minutes or hours it took to stop without stopping.
What is measured?
Speed is most often measured in SI units. Below are not only units, but also examples of where they are used:
- km / h (kilometer per hour) - transport;
- m / s (meter per second) - wind;
- km / s (kilometer per second) - space objects, rockets;
- mm / h (millimeter per hour) - liquids.
To begin with, let's figure out where the fractional line came from and why the unit of measurement is just that. Pay attention to the speed formula in physics. What do you see? The numerator is S (distance, path). What is the distance measured? In kilometers, meters, millimeters. In the denominator, respectively, t (time) - hours, minutes, seconds. Hence, the units of measure of the magnitude are exactly as presented at the beginning of this section.
We fix with you the study of the velocity formula in physics as follows: what distance does the body cover in a specific period of time? For example, a person will walk 5 kilometers in 1 hour. Total: human speed - 5 km / h.
What does it depend on?
Often teachers ask students a question: "What determines the speed?" Schoolchildren are often lost and do not know what to say. In fact, everything is very simple. Just look at the formula to get a hint. The speed of the body in physics depends on the time of movement and distance. If at least one of these parameters is unknown, it will be impossible to solve the problem. In addition, in the example, other types of speeds can be found, which will be discussed in the following sections of this article.
In many problems in kinematics, it is necessary to construct dependency graphs, where on the X axis is time, and on the Y axis is distance, path. From these images, you can easily assess the nature of the speed of movement. It is worth noting that in many professions related to transport, electric machines often use graphics. For example, on the railway.
At the right time we measure the speed
There is another topic that scares high school students - instantaneous speed. In physics, this concept occurs as a definition of the magnitude of speed in an instant period of time.
Let's look at a simple example: the driver drives a train, his assistant monitors the speed from time to time. In the distance, a speed limit sign is visible . You should check how fast the train is moving right now. The assistant to the driver reports at 16:00 that the speed is 117 km / h. This is the instantaneous speed, recorded exactly at 4 pm. After three minutes, the speed became 98 km / h. This is also an instantaneous speed relative to 16 hours 03 minutes.
Start of movement
Without an initial velocity, physics does not represent practically any movement of transport equipment. What is this parameter? This is the speed with which the object begins to move. Suppose a car cannot start driving instantly at a speed of 50 km / h. She needs to accelerate. When the driver presses the pedal, the car smoothly starts moving, for example, at a speed of 5 km / h first, then gradually 10 km / h, 20 km / h and so on (5 km / h is the initial speed).
Of course, you can make a sharp start, which happens to runners-athletes, when a tennis ball is hit with a racket, but still there is always an initial speed. By our standards, only the stars, planets and satellites of our Galaxy do not have it, since we do not know when the movement began and how. After all, until death, space objects cannot stop, they are always in motion.
Uniform speed
Speed in physics is a combination of individual phenomena and characteristics. Distinguish between uniform and uneven movement, curved and rectilinear. Let's give an example: a person follows a straight road with the same speed overcoming a distance of 100 meters from point A to point B.
On the one hand, this can be called straightforward and uniform speed. But if you attach a very accurate speed, route sensors to a person, you will notice that there is still a difference. Uneven speed is when the speed is regularly or constantly changing.
In everyday life and technology
The speed of motion in physics exists everywhere. Even microorganisms move, albeit at a very slow speed. It is worth noting that there is rotation, which is also characterized by speed, but has a unit of measurement - rpm (revolutions per minute). For example, the rotation speed of a drum in a washing machine. This unit of measure is used everywhere where there are mechanisms and machines (engines, motors).
In geography and chemistry
Even water has a speed of movement. Physics is only a subsidiary science in the field of processes occurring in nature. Suppose wind speed, waves in the sea - all this is measured by the usual physical parameters, quantities.
Surely, many of you are familiar with the phrase "speed of a chemical reaction." Only in chemistry does this have a different meaning, since it means how long this or that process will take. For example, potassium permanganate will dissolve faster in water if you shake the vessel.
Invisibility Speed
There are invisible phenomena. For example, we cannot see how particles of light, various radiation move, how sound propagates. But if there were no movement of their particles, then none of these phenomena would exist in nature.
Informatics
Almost every modern person is faced with the concept of "speed" while working on a computer:
- Internet speed;
- page loading speed;
- processor loading speed and so on.
There are a lot of examples of speed in physics.
Having carefully read the article , you got acquainted with the concept of speed, learned what it is. Let this material help you to study the “Mechanics” section in depth, show interest in it and overcome fear when answering lessons. After all, speed in physics is a common concept that is easy to remember.