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Unformatted text preview: 14.5 Gravitational Constant Skill: Be able to calculate the gravitational force between two particles. • Newton's law of universal gravitation gives the gravitational force between two objects of gravitational masses m 1 and m 2 separated by a distance of r 12 : F g =G( m 1 m 2 )/ r 2 ( r/ r ) • w h e r e G is the gravitational constant. G has been determined experimentally to have a value of 6 . 673 × 1011 Nm 2 kg2 . • ( r/ r )= “r hat” is the vector in the direction of r, but with unit magnitude (unit means the magnitude is 1, regardless of the system of units you are using). Binary star systems, two stars rotating about a common center of mass, are found all around the universe. Consider a binary star system where both stars have the same mass and the center of each star is located 10 11 m from the center of mass. The stars each have mass 3 × 10 30 kg. (a)What is the angular speed of the stars? (b)What is the period of the motion, in days? The only thing you are responsible for from Section 14.8 The gravitational force between two spherical objects is the same as the gravitational force between two point particles of the same masses located at the centers of the spheres. 14.6 Gravitational Potential Energy Goal: Be able to calculate changes in an object's gravitational potential energy. • If we choose the gravitational potential between two objects to be zero at infinite separation, then the gravitational potential energy between any two objects is given by U ( r ) = GMm/r . Gravitational potential energy decreases as the separation decreases. Since gravitational potential energy is taken to be zero at infinite separation, this means that it must be negative for anything less than infinite separation....
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This note was uploaded on 05/04/2008 for the course PHYS 2054 taught by Professor Stewart during the Spring '08 term at Arkansas.
 Spring '08
 Stewart
 Physics, Force, Mass

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