Absolutely on all bodies in the universea magic force, somehow attracting them to the Earth (more precisely to its core). Nowhere to escape, nowhere to hide from the universal magical gravitation: the planets of our solar system are attracted not only to the great Sun, but also to each other, all objects, molecules and the smallest atoms are also attracted. Isaac Newton, known even to small children, devoting his life to studying this phenomenon, established one of the greatest laws - the law of universal gravitation.
What is gravity?
The definition and formula have long been known to many.Let us recall that the force of gravity is a certain magnitude, one of the natural manifestations of universal gravitation, namely: the force with which every body is invariably attracted to the Earth.
Gravity is denoted by the Latin letter F.
Gravity: the formula
How to calculate the force of gravity directed ata certain body? What other quantities do you need to know for that? The formula for calculating gravity is quite simple, it is studied in the 7th grade of the general education school, at the beginning of the course in physics. In order not only to learn it, but also to understand, it must be assumed that gravity, which invariably acts on the body, is directly proportional to its quantitative value (mass).
The unit of gravity is named after the great scientist Newton.
Gravity (gravity) is always directedstrictly down, to the center of the earth's core, thanks to its impact, all bodies are equally accelerated downward. The phenomena of gravitation in everyday life we observe everywhere and constantly:
- objects accidentally or specially released from the hands, necessarily fall down to Earth (or to any surface that prevents a free fall);
- The satellite launched into space does not fly away from our planet indefinitely perpendicularly upwards, but it remains to rotate in orbit;
- all rivers flow from the mountains and can not be reversed;
- sometimes a person falls and is injured;
- On all surfaces the smallest specks of dust settle;
- air is concentrated at the surface of the earth;
- heavy to carry bags;
- clouds and clouds drip rain, snow, hail.
Along with the notion of "gravity" is usedthe term "body weight". If the body is placed on a flat horizontal surface, then its weight and gravity are numerically equal, so these two concepts are often substituted, which is not at all correct.
Acceleration of gravity
The concept of "acceleration of free fall" (otherwisespeaking, the gravitational constant) is associated with the term "gravity". The formula shows: in order to calculate the force of gravity, it is necessary to multiply the mass by g (acceleration of the STP).
"g" = 9.8 N / kg, this is a constant value.However, more accurate measurements show that, due to the rotation of the Earth, the value of the acceleration of St. etc. is not the same and depends on the latitude: at the North Pole it is 9.832 N / kg, and at the hot equator = 9.78 N / kg. It turns out that in different places of the planet on bodies possessing equal mass, different gravity is directed (the formula of mg remains unchanged anyway). For practical calculations it was decided not to pay attention to the slight errors of this magnitude and to use the average value of 9.8 N / kg.
Proportionality of such magnitude as forcegravity (the formula proves this), allows you to measure the weight of an object with a dynamometer (similar to ordinary household business). Note that the instrument only shows strength, since it is necessary to know the regional value of "g" to determine the exact mass of the body.
Does gravity work on any (and near, anddistant) distance from the earth's center? Newton put forward the hypothesis that it acts on the body even at a considerable distance from the Earth, but its value decreases inversely proportional to the square of the distance from the object to the core of the Earth.
Gravity in the Solar System
Is there gravity on other planets? The definition and formula for other planets remain relevant. With only one difference in the value of "g":
- on the Moon = 1.62 N / kg (six times less than terrestrial);
- on Neptune = 13.5 N / kg (almost 1.5 times higher than on Earth);
- on Mars = 3.73 N / kg (more than two and a half times less than on our planet);
- on Saturn = 10.44 N / kg;
- on Mercury = 3.7 N / kg;
- on Venus = 8.8 N / kg;
- on Uranus = 9.8 N / kg (almost the same as for us);
- on Jupiter = 24 N / kg (almost two and a half times higher).
