PCS 125 Lecture Notes - Lecture 4: Resultant Force
Document Summary
The earth"s result can be extended to any planet. The table at right gives some escape speeds from various objects. Complete escape from an object is not really possible. The gravitational field is infinite and so some gravitational force will always be felt no matter how far away you can get. This explains why some planets have atmospheres and others do not. Lighter molecules have higher average speeds and are more likely to reach escape speeds. A black hole is the remains of a star that has collapsed under its own gravitational force. The escape speed for a black hole is very large due to the concentration of a large mass into a sphere of very small radius. If the escape speed exceeds the speed of light, radiation cannot escape and it appears black. Two spheres of mass m are separated by a distance r. they are isolated in space with no other masses nearby.
