Gravity comes from a fundamental wave of gravity, which comes from a star that synchronously produces radiation particles such as photons. The energy (momentum and potential energy) generated by this fundamental wave of gravity is huge, which acts on planets such as the earth and forms the so-called gravity in a certain regional space.

The force that an object receives due to the gravity of the earth is called gravity. Gravity is the center of the earth. The direction of gravity is always vertical downward. The magnitude of gravity on an object is directly proportional to its mass. The calculation formula is: G=mg, g is the proportional coefficient, and the magnitude of gravity is about 9.8N/kg.

Gravity varies with latitude, that is to say, the weight of an object with a mass of 1kg is 9.8N, and the point where gravity acts on the object is called the center of gravity.

Extended data

1, gravity is the resultant force of universal gravitation and inertial force, or a component of universal gravitation. The resultant force obtained by the synthesis of force or the component obtained by the decomposition of force are all artificially imagined forces. So gravity is a virtual force.

2, the earth, the moon, Mars, artificial earth satellites, etc. There is no essential difference in physics, and they are all worthy of the name. According to the new definition (gravity is the resultant force of universal gravitation and inertial force on an object),

The gravity of an object varies greatly. For example, the gravity of the same object on the moon is much smaller than that on the earth, and the gravity on the satellite is zero (complete weightlessness, in fact, only the satellite has little gravity on the object).

3. The distance between celestial bodies is much larger than the diameter of celestial bodies, so when calculating the gravitational force between celestial bodies, celestial bodies can be regarded as particles. Except for the celestial body where the object is located, the attraction of other celestial bodies to the object can offset the corresponding inertial force. But in fact, celestial bodies (except artificial celestial bodies) are very large.

The acceleration of objects on the celestial surface is different from that of celestial particles, and it changes at any time. Therefore, the gravity of other celestial bodies can not be completely offset by their corresponding inertial forces, thus changing the gravity of objects on the surface of celestial bodies. This is why the tides of the earth's oceans change.

Baidu encyclopedia _ gravity