This topic will be useful not only for high school students, but even for adults. In addition, the article will be of interest to parents who want to explain simple things from the natural sciences to their children. Among the very important topics is speed in physics.
Quite often, students cannot figure out how to solve problems, distinguish between the available types of speeds, and it is even more difficult to understand scientific definitions. Here we will consider everything in a more accessible language, so that everything is not only 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 measurement and, of course, the meanings of symbols in each formula.
Where does it meet?
To begin with, let's remember that this topic refers to such a section of physics as mechanics, subsection "Kinematics". In addition, the study of speed does not end here, it will be in the following sections:
- optics,
- fluctuations and waves,
- thermodynamics,
- quantum physics and so on.
Also, the concept of speed is found in chemistry, biology, geography, computer science. In physics, the topic "velocity" is most often encountered and studiedin-depth.
In addition, this word is used in everyday life by all of us, especially among motorists, drivers of vehicles. Even experienced cooks sometimes use a phrase such as "beat the egg whites with a mixer on medium speed."
What is speed?
Speed in physics is a kinematic quantity. It means the distance traveled by a body in a certain period of time. Let's say a young man moves from home to a store, covering two hundred meters in one minute. On the contrary, his old grandmother will pass 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, taking very fast long steps.
The same should be said about a 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
At the lesson at school, the speed formula 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 covered by a body when moving from one point in space to another;
- t – 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 might be wondering howspeed from home to work or place of study. But you can find out the distance in advance using a map on your smartphone or computer, or using a paper version, knowing the scale and having a ruler with you. Next, you note the time before you start moving. When you arrive at your destination, see how many minutes or hours it took to pass without stopping.
What is it measured in?
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) - transportation;
- m/s (meter per second) - wind;
- km/s (kilometer per second) – space objects, rockets;
- mm/h (millimeter per hour) - liquids.
Let's first figure out where the fractional bar came from and why the unit of measurement is just that. Pay attention to the physics formula for speed. What do you see? The numerator is S (distance, path). How is distance measured? In kilometers, meters, millimeters. In the denominator, respectively, t (time) - hours, minutes, seconds. Hence, the units of measurement are exactly the same as presented at the beginning of this section.
Let's consolidate with you the study of the velocity formula in physics as follows: what distance will the body overcome in a specific period of time? For example, a person walks 5 kilometers in 1 hour. Total: the speed of a person is 5 km/h.
What does it depend on?
Quite often, teachers ask students the question: "What determines the speed?". Students often get lost and don't know what to say. In fact, everything is verysimply. Just look at the formula for a hint to pop up. The speed of a body in physics depends on the time of motion and distance. If at least one of these parameters is unknown, it will be impossible to solve the problem. In addition, other types of speeds can be found in the example, which will be discussed in the following sections of this article.
In many tasks in kinematics, you have to build dependency graphs, where the X-axis is time, and the Y-axis is distance, path. From such images, one 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.
Measuring speed at the right moment
There is another topic that scares middle school students - instantaneous speed. In physics, this concept occurs as a definition of the magnitude of speed in an instantaneous period of time.
Let's look at a simple example: the driver is driving the train, his assistant is watching the speed from time to time. There is a speed limit sign in the distance. You should check how fast the train is moving right now. The driver's assistant reports at 4:00 pm that the speed is 117 km/h. This is the instantaneous speed recorded exactly at 4 pm. Three minutes later, the speed was 98 km/h. This is also the instantaneous speed relative to 16 hours 03 minutes.
Start of movement
Without the initial speed, physics does not represent almost any movement of the transporttechnology. What is this parameter? This is the speed at which the object starts moving. Let's say a car cannot start moving instantly at a speed of 50 km/h. She needs to speed up. When the driver presses the pedal, the car starts moving smoothly, for example, at first 5 km/h, 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, like runners-athletes, when hitting a tennis ball 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.
Even speed
Speed in physics is a combination of individual phenomena and characteristics. There are also uniform and non-uniform motion, curvilinear and rectilinear. Let's give an example: a person walks along a straight road at the same speed, overcoming a distance of 100 meters from point A to point B.
On the one hand, it can be called rectilinear and uniform speed. But if you attach very accurate speed and route sensors to a person, you will notice that there is still a difference. Uneven speed is when the speed changes regularly or constantly.
In everyday life and technology
The speed of movement in physics exists everywhere. Even micro-organisms move, letand at a very slow pace. 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 speed of rotation of the drum in a washing machine. This unit of measure is used wherever there are mechanisms and machines (engines, motors).
In geography and chemistry
Even water has a movement speed. Physics is just a subsidiary science in the field of processes occurring in nature. For example, 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 "the rate of a chemical reaction." Only in chemistry does it have a different meaning, since it means how long this or that process will take place. For example, potassium permanganate will dissolve faster in water if you shake the vessel.
Invisible Speed
There are invisible phenomena. For example, we cannot see how particles of light, various radiations move, how sound propagates. But if there was 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;
- CPU loading speed and so on.
There are a huge number of examples of the speed of movement in physics.
After reading the article carefully, you got acquainted with the conceptspeed, find out what it is. Let this material help you study the "Mechanics" section in depth, show interest in it and overcome fear when answering in the lessons. After all, speed in physics is a common concept that is easy to remember.
