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In particular, a non-uniform gravitational field can produce a torque on an object, even about an axis through the center of mass. The center of gravity seeks to explain this effect. Formally, a center of gravity is an application point of the resultant gravitational force on the body. Such a point may not exist, and if it exists, it is not unique.
The equivalence principle is the hypothesis that the observed equivalence of gravitational and inertial mass is a consequence of nature. The weak form, known for centuries, relates to masses of any composition in free fall taking the same trajectories and landing at identical times.
According to this principle, a uniform gravitational field acts equally on everything within it and, therefore, cannot be detected by a free-falling observer. Conversely, all local gravitational effects should be reproducible in a linearly accelerating reference frame, and vice versa.
Gravitational time dilation in the Earth's gravitational field has been measured numerous times using atomic clocks, [67] while ongoing validation is provided as a side effect of the operation of the Global Positioning System (GPS). [68] Tests in stronger gravitational fields are provided by the observation of binary pulsars. [69]
The basic point is that since within General Relativity, gravitational fields couple to each other, this can effectively increase the gravitational interaction between massive objects. The additional gravitational strength then avoid the need for dark matter. This field coupling is the origin of General Relativity's non-linear behavior.
In classical mechanics, a gravitational field is a physical quantity. [5] A gravitational field can be defined using Newton's law of universal gravitation. Determined in this way, the gravitational field g around a single particle of mass M is a vector field consisting at every point of a vector pointing directly towards the particle. The ...
To understand the gravity of Mars, its gravitational field strength g and gravitational potential U are often measured. Simply, if Mars is assumed to be a static perfectly spherical body of radius R M , provided that there is only one satellite revolving around Mars in a circular orbit and such gravitation interaction is the only force acting ...
As part of that, the metric gravitational field , , =,,,, is redefined and decomposed into the non-relativistic gravitational (NRG) fields (,,) : is the Newtonian potential, is known as the gravito-magnetic vector potential, and finally is a 3d symmetric tensor known as the spatial metric perturbation.