PHY183-Lecture38 - April 4, 2006 Physics for...

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Unformatted text preview: April 4, 2006 Physics for Scientists&Engineers 1 1 Physics for Scientists & Physics for Scientists & Engineers 1 Engineers 1 Spring Semester 2006 Lecture 38 April 4, 2006 Physics for Scientists&Engineers 1 2 Gravitation Gravitation ! We have been treating the gravitational force only in terms of a constant acceleration, g = 9.81 m/s 2 ! Newton realized that gravity also determines the motion of objects in space. ! But the gravitational force must vary with distance. ! Here is a picture of astronauts floating over the Hubble Space Telescope April 4, 2006 Physics for Scientists&Engineers 1 3 Gravitational Force Gravitational Force ! The general expression for the magnitude of the gravitation interaction between two masses m 1 and m 2 a distance r apart is ! G is the universal gravitation const. ! It usually suffices to use F ( r ) = G m 1 m 2 r 2 G = 6.6742(10) ! 10 " 11 m 3 kg-1 s " 2 G = 6.67 ! 10 " 11 m 3 kg-1 s " 2 1 2 21 2 1 2 1 2 12 2 1 2 21 1 21 1 2 2 ( ) | | ( ) | | ( ) ( ) mm F r G r r mm F r G r r F r F r e e = ! ! = ! ! = ! r r r r r r r r r r r r r r 2 1 r r r = ! r r r 1 1 21 1 2 2 2 r r e r e r ! = = ! ! r r r r r r April 4, 2006 Physics for Scientists&Engineers 1 4 Superposition of Gravitational Forces Superposition of Gravitational Forces ! If more than one object interacts gravitationally with an object, the superposition principle tells us that all gravitational forces on that object add up ! We know the force of object...
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This note was uploaded on 03/19/2008 for the course PHY 183 taught by Professor Wolf during the Spring '08 term at Michigan State University.

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PHY183-Lecture38 - April 4, 2006 Physics for...

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