Earth gravitational force

It is easiest to appreciate what is meant by mass iadirecdy, by observing the influence of forces on objects, eg, by picking up an object and sensing the effect of the earth s gravitational force acting on it, and hence "feeling" its weight. 

Book II investigates the dynamical conditions of fluid motion. Book III displays the law of gi avitatioii at work in the solar system. It is demonstrated from the revolutions of the six known planets, including Earth, and their satellites, though Newton could never quite perfect the difficult theory of the Moon s motion. It is also demonstrated from the motions of comets. The gravitational forces of the heavenly bodies are used to calculate their relative masses. The tidal ebb and flow and the precession of the equinoxes is explained m terms of the forces exerted by the Sun and Moon. These demonstrations are carried out with precise calculations. 

The solid plates that resulted from the cooling process at the surface of the eanli were able to float on the remaining molten inner portion of the earth. Because of the rotational motion of the earth about its own axis and the earth s motion in the solar system, inertial and gravitational forces have produced great interactive forces between the plates. It is speculated that these interactive forces have led to plate contact and situations where one plate has slid over another. The great forces created by plate tectonics are likely responsible for the forces that have resulted in the folding and faulting of the earth s crust [30j. 

Most of the rocks that make up the upper crust of the earth lie hidden beneath layers of sediments, unconsolidated accumulations of particles derived from the weathering of minerals and rocks (see Fig. 44 and Textbox 45) (Keller 1957). Once formed, the particles are either carried away or moved by the wind, rain, and gravitational forces into the seas and oceans or, before they get there, into depressions in the land. There they accumulate in a wide range of shapes and sizes (see Table 49) (Rocchi 1985 Shackley 1975). 

One more important property of Jupiter must be mentioned the Earth owes its relatively quiet periods (in geological terms) to the huge gravitational force of the giant planet. Jupiter attracts most of the comets and asteroids orbiting in its vicinity, thus protecting the Earth from impact catastrophes ... 

One of the projects planned for the next decade is Darwin, to be organised by ESA. Darwin will be a flotilla of four or five spacecraft that will search for Earth-like planets around other stars and analyse their atmospheres for the chemical signature of life. Three of the spacecraft will carry 3 1 m space telescopes , which will form the Infrared Space Interferometer IRSI they will be stationed 1.5 million kilometres from Earth, in the opposite direction from the Sun, at the Lagrangian Point L2 (a libration point at which the gravitational forces of the Earth and the sun cancel out). 

The ability of the superconductor to overcome gravitational forces has led to the famous demonstration, typically involving an oxide superconductor and a rare-earth magnet, in which the magnet is levitated above the superconductor when it is cooled... 

Weight is more complicated. By definition, weight is the gravitational force exerted on an object by the nearest most massive body, such as Earth. The weight of an object, therefore, depends entirely upon its location, as is shown in Figure 1.16. 

On the moon, a gold bar weighs less than it does on Earth. This is because the moon is much less massive than Earth hence, the gravitational force exerted by the moon on the bar is much less. On Jupiter, the gold bar would weigh more than it does on Earth because of the greater gravitational force exerted on the bar by this very massive planet. 

Weight The gravitational force of attraction between two bodies (where one body is usually Earth). 

The force on a sedimenting particle increases with the velocity of the rotation and the distance of the particle from the axis of rotation. A more common measurement of F, in terms of the earth s gravitation force, g, is relative centrifugal force, RCF, defined by Equation 7.2. 

Compared to the stars, the earth is a tiny astronomical body. Therefore, its comparative gravitational force is also very weak. When the earth was formed, it was not able to hold such a light element. As result, most hydrogen escaped into space. 

The radius of the Earth at the Equator is 6,378 km, so r in Equation 3.10 changes little as we move a short distance from the surface of the earth. The gravitational force is almost the same on top of Mt. Everest as it is at sea level. This lets us approximate the gravitational attraction to the Earth as ... 

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