AST 111: LECT 6: Gravitation and the Waltz of the Planets (cont.)
-Kepler’s laws can apply to any pair of orbiting objects
Galileo
-Galileo’s discoveries with a telescope
- Galileo didn’t invent the telescope, but he perfected the instrument and was the
first person to use it for astronomical observing
-With his telescopes, he discovered:
- Mountains on the Moon
- Spots on the Sun
- Moons of Jupiter
- Phases of Jupiter
-Father of modern astronomy and Modern experimental physics
Issac Newton
-developed a set of laws that describes the motion of all objects, not just planets
-Newton’s 1st Law
- Law of Inertia
- A body at remains at rest, or moves in a straight line at constant speed, unless
acted upon by an outside force
-Newton’s 2nd Law
- The acceleration of an object (of mass m) is proportional to the net outside fore
acting on it, F=ma
-Newton’s 3rd Law
- Whenever one body exerts a force on a second body, the second body exerts
-Newton’s Law of Universal Gravitation:
- 2 bodies attract eachoter with a force that is directly proportional to the product of
their masses and inversely proportional to the square of the distance between
them, or F=GMm/r2
Describing orbits with energy and gravity
-Energy comes in many forms
- such as chemical, thermal, motion, etc.
- as we lose POTENTIAL energy, we gain KINETIC energy, and energy is never
lost
Gravitational pull between the moon and earth produce tides
-the moon (and the sun’s) gravitational attraction creates tidal buldges