Earth moon distance

PROBLEM 2.4.1. Given that the average earth-moon distance is Rem = 3.844 x 108 m and that the moon s revolution around the earth is 27.3 days (from which its tangential orbital velocity is vm = 1.0186 x 103 m s 1), compute the mass of the earth. 

The overwhelming majority of filaments are made of NS-W (sag-resistant tungsten). Only for special shock and vibration resistant lamps are W-Th02 or W-Re wires used. Every year, about 20 billion meters of lamp wire are drawn, a length which corresponds to about 50 times the earth-moon distance [7.8]. 

The distance to the moon. Hipparchus in 130 BCE or thereabouts used the curve of the terrestrial shadow across the moon during eclipses to estimate this in units of earth radii and got roughly the right answer. A geometrical method for determining the ratio of sun distance to moon distance failed, because the lunar orbit is not a circle. 

The mass of an object is directly associated with its weight. The weight of a body is the pull on the body by the nearest celestial body. On earth, the weight of a body is the pull of the earth on the body, but on the moon, the weight corresponds to the pull of the moon on the body. The weight of a body is directly proportional to its mass and also depends on the distance of the body from the center of the earth or moon or whatever celestial body the object is near. In contrast, the mass of an object is independent of its position. At any given location, for example on the surface of the earth, the weight of an object is directly proportional to its mass. 

The much-closer Moon would have had a greater influence on the tidal rise and fall of the oceans. At the moment, the mid-ocean tidal rise and fall far removed from the land masses is of order 1 m but if the Moon had been formed at a distance of around 40 000 km the tidal variation would have been of the order 100-1000 m. Large regions of the Earth s surface would have had a refreshed water supply every 4 h in the extreme cases of the model. Only well inland on the early land masses would there have been a dry environment, perhaps with fresh water replenishment. The early ideas of Darwin called for a Tittle warm pool to act... 

Figure 2.3. A schematic of the Chandra Observatory showing the typical components including the solar arrays, aspect cameras, mirror assembly, instrument module, and optical bench. The Chandra Observatory weighs 4800 kg and orbits the Earth every 64 hours in a 10,000 by 140,000 km orbit that extends 1/3 of the distance the moon. Including the solar panels, the observatory s dimensions are 14m by 20m.

Earth s moon is a roughly spherical, rocky body orbiting Earth at an averse distance of 238,000 mi (382,942 km). Its diameter is about one-fourth Earth s diameter. Compared to moons cf other planets, this is a... 

It was asked what velocity and height must a satellite have so that it remains stationary above the same point on Earth s surface that is, have the same rotation period, one day, as the earth. Three such satellites, placed 120 degrees apart around the earth, could make instantaneous communication with all points on the earth s surface possible. From the fact that period squared is proportional to the cube of the radius and the above periods of the moon and satellite and the moon s distance, it is found that the communication satellite would have to be located 26,000 mi from earth s center or 22,000 mi above the surface. Its velocity must be about 6,800 MPH. Many such satellites are now in space around the earth. 

For comparison, the distance from the Earth to the moon is 3.8 X 10 m. The diffusion constant is... 

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