✋ 🎰 🚴🏼 Forces of the Earth. Earth's gravitational force 🤰 🕺 🔃

Each change always requires some effort. Any changes will not happen without any influence. And an obvious example of this is our home planet, formed under the influence of various factors over billions of years. It is also important that the constant processes of Earth change are the result of not only external forces, but also internal forces, those that are hidden deep in the bowels of the geosphere.

And if, after two or three decades, the appearance of our planet may well change beyond recognition, then clearly it will not be superfluous to understand the processes whose influence led to this.

Inside change

Uplands and depressions, bumps and roughness, as well as many other features of the land topography - all this is constantly updated, crumbled and formed by powerful internal forces. Most often, their manifestation remains out of our sight. However, even right at that moment, the Earth is gradually undergoing some form of change, which in the long run will become much more significant.

Ever since the days of the ancient Romans and Greeks, the uplift and subsidence of various sections of the lithosphere were observed, causing all changes in the outlines of the seas, land and oceans. Many years of scientific research using various technologies and devices fully confirm this.

Mountain growth

Slow movement of individual sections of the earth's crust gradually leads to their overlapping. Faced in horizontal movement, their thicknesses are bent, crumpled and transformed into folds of different scales and steepness. In total, science distinguishes two types of mountain building movements (orogenesis):

Formation bending - forms both convex folds (mountain ranges) and concave (hollows in the mountains). It is from this that the name of the folded mountains came to be, which over time is gradually destroyed, leaving only a foundation. Plains form on it.
Rupture - strata of rocks can not only crumple into folds, but also undergo fractures. Thus, folded-blocky (or simply blocky) mountains are formed: skids, grabens, horsts and their other components arise during vertical displacement (raising up / down) of the earth's crust relative to each other.

But the internal strength of the Earth is capable of not only crushing the plains into mountains and destroying the former outlines of hills. The movements of lithospheric plates also give rise to earthquakes and volcanic eruptions, which are often accompanied by monstrous devastation and human deaths.

Breath from the bowels

It is hard to imagine that the notion of “volcano”, familiar to every person in ancient times, had a much more formidable connotation. At first, the true cause of this phenomenon was customarily associated with the disfavor of the gods. Ejected from the bowels of the stream of magma was considered a severe punishment from above for the infringements of mortals. Catastrophic losses due to volcanic eruptions have been known since the dawn of our era. Thus, for example, the magnificent Roman city of Pompeii was wiped off the face of planet Earth. The power of the planet at that moment was manifested by the crushing power of the now famous volcano Vesuvius. By the way, the authorship of this term is historically assigned to the ancient Romans. So they called their god of fire.

For modern man, a volcano is a cone-shaped elevation above cracks in the crust. Through them , magma is erupted to the surface of the earth, sea or ocean floor along with gases and rock fragments. In the center of such a formation is a crater (translated from Greek - "bowl"), through which the release occurs. When solidified, magma turns into lava and forms the outlines of the volcano itself. However, even on the slopes of this cone cracks often appear, thereby forming parasitic craters.

equal to the force of gravity of the earth

Quite often, eruptions are accompanied by earthquakes. But the greatest danger to all living things is precisely emissions from the bowels of the Earth. The release of gases from magma occurs extremely quickly, so powerful explosions subsequently become a commonplace.

According to the type of action, volcanoes are divided into several types:

The current ones are those about the last eruption of which there is documented information. The most famous among them: Vesuvius (Italy), Popocatepetl (Mexico), Etna (Spain).
Potentially acting - are erupted extremely rarely (once every several thousand years).
Extinct - volcanoes have this status, the last eruptions of which have not been documented.

Earthquake effect

Shifts of rocks often provoke fast and strong vibrations of the earth's crust. Most often this happens in the region of high mountains - these areas to this day continuously continue to form.

The place of origin of the shifts in the depths of the earth's crust is called the hypocenter (focus). Waves propagate from it, which create oscillations. A point on the surface of the earth, directly below which the focus is located - the epicenter. In this place, the strongest tremors are observed. As they move further from this point, they gradually fade away.

The science of seismology, which studies the phenomenon of earthquakes, identifies three main types of earthquakes:

Tectonic - the main mountain-forming factor. It arises as a result of collisions of oceanic and continental platforms.
Volcanic - arise as a result of flows of red-hot lava and gases from under the bowels of the earth. Usually they are rather weak, although they can last several weeks. Most often they are harbingers of volcanic eruptions, which is fraught with much more serious consequences.
Landslide - arise as a result of the collapse of the upper layers of the earth, covering the void.

The strength of earthquakes is determined on a ten-point Richter scale using seismological instruments. And the greater the amplitude of the wave that occurs on the earth's surface, the more noticeable will be the damage. The weakest earthquakes, measured at 1-4 points, can be ignored. They are recorded only by special sensitive seismological instruments. For people, they appear maximum in the form of trembling glasses or slightly moving objects. For the most part, they are completely invisible to the eye.

In turn, fluctuations of 5-7 points may well cause various damage, albeit minor. Stronger earthquakes already pose a serious threat, leaving behind destroyed buildings, almost completely destroyed infrastructure and human losses.

Every year, seismologists record about 500 thousand vibrations of the earth's crust. Fortunately, only a fifth of this number is really felt by people and only 1000 of them cause real damage.

Modified by the wind

The destruction and transformation of rocks mainly occurs under the influence of weathering. It does not create new relief forms, but destroys solid materials to a loose state.

In open spaces where there are no forests and other obstacles, sand and clay particles can travel considerable distances with the help of winds. Subsequently, their clusters form eolian relief forms (the term comes from the name of the ancient Greek god Aeolus - the lord of the winds).

An example is sandy hills. Desert dunes are created solely by wind. In some cases, their height reaches hundreds of meters.

In the same way, sedimentary rock deposits composed of dusty particles can accumulate. They have a grayish-yellow color and are called loesses.

It should be remembered that, moving at high speed, various particles not only accumulate in new formations, but also gradually destroy the relief encountered on its way.

There are four types of weathering of rocks:

Chemical - consists in chemical reactions between minerals and the environment (water, oxygen, carbon dioxide). As a result, rocks undergo destruction, their chemical component undergoes changes with the further formation of new minerals and compounds.
Physical - causes mechanical decomposition of rocks under the influence of a number of factors. First of all, physical weathering occurs with significant temperature fluctuations during the day. Winds, along with an earthquake, volcanic eruptions and mudflows, are likewise factors of physical weathering.
Biological - is carried out with the participation of living organisms, the activity of which leads to the creation of a qualitatively new formation - the soil. The influence of animals and plants is manifested in mechanical processes: crushing rocks by roots and hooves, digging holes, etc. Microorganisms play a particularly large-scale role in biological weathering.
Radiation, or solar weathering. A typical example of the destruction of rocks with a similar effect is lunar regolith. Along with this, radiation weathering also affects the previously listed three species.

All these types of weathering are often manifested in combination, combining in various variations. However, different climatic conditions also affect one's predominance. For example, in places with a dry climate and in mountainous regions, physical weathering is often found. And for areas with a cold climate, where temperatures often fluctuate up to 0 degrees Celsius, not only weathering by frost is characteristic, but also organic, coupled with chemical.

Gravitational impact

Not a single list of the external forces of our planet will be complete, if not to mention the fundamental interaction of all material bodies - this is the gravitational force of the Earth.

Destroyed by numerous natural and artificial factors, rocks are always subject to movement from elevated areas of soil to lower. So landslides, scree are generated, happen and sat down with landslides. The gravitational force of the Earth at first glance may seem something invisible against the background of powerful and dangerous manifestations of other external factors. However, all their impact on the relief of our planet would simply be leveled without universal gravitation.

We will examine in more detail what effect gravity has. Under the conditions of our planet, the weight of any material body is equal to the gravitational force of the Earth. In classical mechanics, this interaction describes the Newtonian law of universal gravitation, known from school. According to him, the gravity F is the product of m by g, where m is the mass of the object, and g is the acceleration of gravity (always equal to 10). In this case, the gravity of the Earth’s surface affects all bodies located both directly on it and near it. If the body is affected solely by gravitational attraction (and all other forces are mutually balanced), it is subject to free fall. But for all its ideality, there are conditions where the forces acting on a body near the surface of the Earth are essentially leveled and are characteristic of a vacuum. In everyday reality, one has to face a completely different situation. For example, the value of air resistance also affects a falling object in the air. And although all the same the Earth’s gravity will be much stronger, this flight will no longer be truly free by definition.

It is interesting that the effect of attraction exists not only in the conditions of our planet, but also at the level of our solar system as a whole. For example, what attracts the moon more? Earth or the sun? Without a degree in astronomy, many will probably be surprised at the answer.

Because the gravitational force of the satellite by the Earth is inferior to the solar by about 2.5 times! It will be reasonable to think about how the celestial body does not tear the moon from our planet with such a strong impact? Indeed, in this regard, the magnitude of the Earth’s gravitational force with respect to the satellite is significantly inferior to that for the Sun. Fortunately, science is able to answer this question.

Theoretical astronautics for such cases uses several concepts:

The scope of the body M1 is the surrounding space around the object M1, within which the object m moves;
The body m is an object moving freely in the sphere of action of the object M1;
The body M2 is an object that exerts a disturbing effect on this movement.

It would seem that gravitational force should be decisive. The Earth attracts the Moon much weaker than the Sun, however, there is another aspect that has a final effect.

The whole point boils down to the fact that M2 seeks to break the gravitational connection between objects m and M1 by endowing them with different accelerations. The value of this parameter directly depends on the distance of the objects to M2. However, the difference between the accelerations delivered by the body M2 by m and M1 will be less than the difference between the accelerations m and M1 directly in the gravitational field of the latter. This nuance is the reason why M2 is not able to tear m from M1.

Imagine a similar situation with the Earth (M1), the Sun (M2) and the Moon (m). The difference in the accelerations that the Sun creates with respect to the Moon and the Earth is 90 times smaller than the average acceleration that is characteristic of the Moon with respect to the Earth’s sphere of action (its diameter is 1 million km, the distance between the Moon and the Earth is 0.38 million kilometers). The decisive role is played not by the force with which the Earth attracts the Moon, but by the large difference in accelerations between them. Thanks to this, the Sun is only able to deform the orbit of the Moon, but does not tear it from our planet.

Let's go even further: the effect of gravity, to varying degrees, is also characteristic of other objects of our solar system. What effect does it have, given the fact that gravity on Earth is significantly different from that of other planets?

This will affect not only the movement of rocks and the formation of new landforms, but also their weight. Be sure to note that this parameter is determined by the magnitude of the attractive force. It is directly proportional to the mass of the planet in question and inversely proportional to the square of its radius.

If our Earth were not flattened at the poles and extended in the region of the Equator, the weight of any body on the entire surface of the planet would be the same. But we do not live on a perfect ball, and the equatorial radius is longer than the polar one by about 21 km. That is why the weight of the same object will be heavier at the poles and easiest at the equator. But even at these two points, gravity on Earth differs slightly. The tiny difference in the weight of the same object can only be measured using spring weights.

And a completely different situation will develop in the conditions of other planets. For clarity, pay attention to Mars. The mass of the red planet is 9.31 times less than the earth, and the radius is 1.88 times less. The first factor, respectively, should reduce the force of gravity on Mars in comparison with our planet by 9.31 times. At the same time, the second factor increases it by 3.53 times (1.88 squared). As a result, the force of attraction on Mars is about a third of the Earth's (3.53: 9.31 = 0.38). Accordingly, a rock with a mass on Earth of 100 kg will weigh exactly 38 kg on Mars.

Given the inherent gravity of the Earth, it can be compared in one row between Uranus and Venus (whose attraction is 0.9 times less than Earth's) and Neptune and Jupiter (their attraction is 1.14 and 2.3 times greater than ours). Pluto was noted as the least impact of gravity - 15.5 times less than Earth conditions. But the strongest attraction is fixed on the Sun. It exceeds ours by 28 times. In other words, a body weighing 70 kg on Earth there would be heavier up to about 2 tons.

Water will flow under the bed

Another important creator and at the same time destroyer of reliefs is moving water. Its flows form wide river valleys, canyons and gorges with their movement. However, even small amounts of it during leisurely movement are able to form a ravine-girder relief in place of plains.

Punching your way through any obstacles is not the only side of the influence of currents. This external force also acts as a transporter of rock debris. Thus various relief formations are formed (for example, flat plains and growths along rivers).

In a special way, the influence of flowing water affects soluble rocks (limestone, chalk, gypsum, rock salt) located close to land. Rivers gradually remove them from their path, rushing into the depths of the earth's bowels. This phenomenon is called karst, as a result of it new forms of relief are formed. Caves and craters, stalactites and stalagmites, precipices and underground reservoirs - all this is the result of a long and powerful activity of water masses.

forces acting on the body at the surface of the earth

Ice factor

Along with running waters, glaciers take no less part in the destruction, transportation and deposition of rocks. Thus creating new forms of relief, they smooth the rocks, form stained hills, ridges and hollows. The latter are often filled with water, turning into glacial lakes.

The destruction of rocks through glaciers is called exazration (glacial erosion). When penetrating river valleys, ice puts strong pressure on their bed and walls. Loose particles are torn off, some of them freeze and thereby contribute to the expansion of the bottom depth walls. As a result, river valleys take the form with the least resistance to advance ice - a trough-like profile. Or, according to their scientific name, glacial trogs.

The melting of glaciers contributes to the creation of zander - flat formations consisting of particles of sand accumulated in frozen water.

We are the external force of the Earth

Given the internal forces acting on the Earth, and external factors, it's time to mention you and me - those who have been making enormous changes to the life of the planet for more than a dozen years.

All relief forms created by man are called anthropogenic (from the Greek anthropos - man, genesisum - origin, and the Latin factor - business). Today, the lion's share of this type of activity is carried out using modern technology. Moreover, new developments, research and impressive financial support from private / state sources ensure its rapid development. And this, in turn, constantly stimulates the buildup of the anthropogenic influence of man.

Especially exposed to changes in the plains. This area has always been a priority for settlement, construction of houses and infrastructure. Moreover, the practice of constructing embankments and artificial leveling of the relief has become quite commonplace.

The environment is also changing for the purpose of mining. With the help of technology, people dig huge quarries, drill mines, make mounds at the dump sites of waste rock.

Often the scale of human activity is comparable with the influence of natural processes. For example, modern technological advances give us the opportunity to create huge channels. And for a much shorter time, when compared with the similar formation of river valleys by the flow of water.

The processes of destruction of the terrain, called erosion, are significantly exacerbated by human activity. First of all, the soil is negatively affected. This is facilitated by the plowing of the slopes, general deforestation, immoderate grazing of cattle, laying of the road surface. Erosion is aggravated even more by the growing pace of construction (this is especially true for the construction of residential buildings, which require such additional work as, for example, grounding, in which the earth's resistance is measured).

The last century was marked by erosion of about a third of all world cultivated land. The largest scale of these processes took place on large agricultural areas of Russia, the USA, China and India. Fortunately, the problem of land erosion is being actively addressed internationally. However, the main contribution to reducing the detrimental effect on the soil and the restoration of previously destroyed areas will bring scientific research, new technologies and competent methods of their application by man.

Forces of the Earth. Earth's gravitational force