I use this ppt. to teach Universal Gravitation to mt high school Physics classes. It's a real time saver, and I think it covers the topic well. Of course I add/augment a lot of stuff as I go along.
9. SO IF: m 1 m 2 d THEN: F g = F d 2m 1 m 2 F g = 2F 2d m 1 m 2 F g = F / 4 d/2 2m 1 2m 1 F g = 16F
10. BUT: This was not overly useful, in order to use the equation to calculate the forces of attraction between two objects, a constant was needed. = Is theoretically very important Gets you something you can really use!
11. Henry Cavendish Determined the UNIVERSAL GRAVITATIONAL CONSTANT By finding the force needed to twist the torsion fiber created by the movement of the small masses ( m ) toward the large masses ( M ) over a known distance. Here’s how it worked.
12. d 2 Using Newton’s equation we can state that: m 1 m 2 = K F g Rearranging to solve for K we get: K = F g d 2 m 1 m 2
13. Cavendish set up his experiment with m1, m2, d, and Fg as known quantities. He was then able to solve for K. He renamed it G, the UNIVERSAL GRAVITATIONAL CONSTANT G = 6.67 x 10 -11 N m 2 Kg 2