# How does the gravitational force come about

### Gravity

• ### Subject: Physics

Theme: Physics in everyday life
Gravitation related to everyday life

1.introduction
2.Why man stands on earth.
3.Running water and bodies of water
4.Falling objects
5.Gravity
6.Law of gravitation with calculation
7.Weight force with calculation
8.The free fall We are objects that stand on earth. We are objects that are attracted by the force of gravity, that is, from the center of the earth. For example, my person hits earth at 510.12 N. Every body, every object and every thing is attracted to the center of the earth.

(Picture from Google under the term people on www.jova-nova.com)

You can feel the force of attraction very strongly in the muscles, for example when lifting a large and heavy stone. In order to offer some resistance to the attraction, we need a lot of strength.

Water is a liquid body that is also attracted. When water flows, it is drawn towards the center of the earth. Waters such as ocean, sea, lake, river, stream and pond do not drip or flow into space because there are very strong attractive forces between them and the earth.

(See Völcker Diethelm, Physics Mechanics, Liquids & Gases, Thermal Science, Acoustics 1997, Intermediate Level 1: p. 27 and 182)

Isaac Newton found out that when objects fall free, gravitational forces make them faster, i.e. they are accelerated. Objects thrown horizontally and vertically experience the same force. The object moves further before it falls to the ground if it is shot quickly (cf. Microsoft Encarta Encyclopedia 1993-2000, animation of Isaac Newton's law of gravitation).
You can see this in sports too. Such as hammer throwing, discus throwing, javelin throwing, etc., but also normal ball games. The ball is thrown horizontally, through the rapid movement it reaches a certain distance and falls back to the ground due to the force of weight.

All bodies attract each other. This happens because of their mass. This attraction is known as gravitational force or mass attraction. The gravitational force acts between the centers of gravity, i.e. the centers, and depends on the masses and the distance between the bodies (cf. Szallies Bernhard, Physik kurz & klar 1993, Vol.2: 41).
Sometimes gravity and gravitation are used as the same meaning, but gravity refers to the gravitational force between the earth and bodies or at a shorter distance from it (see Microsoft Encarta Encyclopedia 1993-2000, term: gravitation).
This force of attraction does not only work between the earth and a body, because it is generally said that bodies have an attractive nature (cf. Völcker Diethelm, Physik Mechanik, Fluid & Gase, Wärmelehre, Akustik 1997, Mittelstufe 1:26).

A physicist puts it this way:
"Bodies attract each other. The force of attraction increases sharply when the distance between the bodies decreases. It decreases sharply when the distance increases."

(See Völcker Diethelm, Physics, Mechanics, Liquids & Gases, Thermal Science, Acoustics 1997, Intermediate Level 1:26) This law is named after the English physicist Sir Isaac Newton. The formula for the law is:

For the law, the formula symbols mean: m1 and m2 the masses of the two attractive bodies, F the gravitational force that prevails between the bodies, r is the distance between the centers of gravity and G the gravitational constant. The gravitational constant is a natural constant that is independent of the material. The value of this constant was measured for the first time in 1798 by Henry Cavendish, a British physicist, using a rotary balance. The most accurate value so far is: (Cf. Microsoft Encarta Encyclopedia 1993-2000, term: Gravitation and / with Szallies Bernhard, Physik Kurz & Klar 1993, Vol. 2: 41)

Example:

given:m1 = 67 kg

m2 = 52 kg

r = 1m

tot .:F in N (Newtons)

Solution:

G = 6.67259 * 10-11m1 * m2

kg2
F = 6.67259 * 10-11m1 * m2* 67kg * 52kg

(kg² and m² can be shortened)

kg21m
F = 2.3247 * 10-6
N = 0.0000023247 N
================

This is a very small force of attraction between the two bodies and yet it can also be measured.

One consequence of gravitation is the weight that a body experiences. It is the force with which a body hits the earth. Falling objects are accelerated by gravity. (Cf. Szallies Bernhard, Physics Brief & Clear, Vol 1:50)
A body experiences this weight force, but does not have it. But not always, because it only occurs when the body is near the surface of the earth. The weight force is not the same everywhere. (See Völcker Diethelm, Physics, Mechanics, Liquids & Gases, Thermal Science, Acoustics 1997, Intermediate Level 1:27)
"From the poles to the equator, the weight of each body decreases by 0.5%." (Cf. Szallies Bernhard, Physik kurz & klar 1993, Vol. 2: 42)
This is due to the fact that the gravitational force decreases from the further distance from the center of the earth and the centrifugal force increases.

The mass m, which is on the earth's surface, experiences a weight force There is a force of attraction between the center of the earth and the mass
The centrifugal force acts perpendicular to the earth's axis and is created by the rotation of the earth around itself. The weight force is influenced by the centrifugal force as it pulls the weight force outwards and gravity prevails from the center of the earth. “Usually the weight on the earth is equated with the gravitational force, neglecting the centrifugal force.” (Szallies Bernhard, Physik kurz & klar 1993, Vol the centrifugal force is neglected. (Cf. Szallies Bernhard, Physics Brief & Clear 1993, Vol. 2:42)

The weight with which a body hits the earth is given by the formula:

G = m * g

calculated. Here m is the mass of a body and g is the acceleration due to gravity. (Cf. Ahlmann Karl-Heinz, Schülerduden "The Physics" 1989, term: weight: p.159)

Example calculation:

The weight of a bicycle is 5 kg. In order to calculate the force with which the bicycle hits the surface of the earth, one calculates the formula of weight force. The acceleration due to gravity is

given: g = 9.81 N total: G in N

kg

m = 5 kg

Sol .: G = m * g

G = 5 kg * 9.81 N (kg can be shortened)

kg

G = 49 N

===========

Answer: The bicycle hits the earth with a force of 49 N.

Free falling bodies perform an evenly accelerated movement. The mass of the body does not matter. The acceleration due to gravity always has approximately the same amount, regardless of how long the fall distance is.

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