2 Newton’s Law of Universal Gravitation Newton Did not discover gravity, but he did discover gravity was universal. In other words, everything pulls on everything else. States: Every object attracts every other object with a force that for any two objects is directly proportional to the mass of each object, and indirectly proportional to the distance between them. In Simple Terms: The greater the mass, the greater the attraction. The greater the distance, the weaker the attraction.
3 Universal Gravitational Constant There is a constant in value for this universal attraction Symbol: G Value: 6.67 X Nm2/Kg2Formula: F= G(m1m2/d2) Where “d” is the distance between the center of mass for the two objects.
4 What is “G”? “G”, or the Universal Gravitational Constant first measured by Henry Cavendish 150 years after Newton’s discovery of Universal GravitationShows us that the force of gravity is a very weak forceEasy to notice with large masses, difficult to notice with small masses
5 Sample QuestionThe gravitational force of attraction between Earth and the sun is 1.6 x 1023 N. a) What would this force have been if Earth were twice as massive? b) What would the force be if the distance doubled?
6 Sample QuestionOliver, whose mass is 65 Kg, and Olivia, whose mass is 45 Kg, sit 2.0 m apart in their physics classroom. A) What is the force of gravitational attraction between Oliver and Olivia? B) Why don’t they drift towards each other?