Question #8: Calculate the angular distance that Mars traveled between 08/09/03
ID: 3309033 • Letter: Q
Question
Question #8: Calculate the angular distance that Mars traveled between 08/09/03 and 09/08/03, compare that to the angular distance that Mars traveled between 9/15/02 and 10/14/02. Which one of those distances is the largest? (Show both calculations) When is Mars moving the fastest, when it is closest or furthest from the Sun? 5 Model Building In all of science, we try to build up explanations of the universe. These explanations can come in the form of words, equations, 3-d structures that we can manipulate, computer programs, or other forms. In science we call these explanations models. Scientific models are constructed to explain nature. Models are constructed out of the findings of our observations and experiments. Once we have a good model, we can apply it to other areas. So what is our model of the motion of the planets? Question #9: What should our model say about the shape of orbits? Which of Kepler's Law tells us this? Question #10: What should our model say about the speed of objects in orbit? Which of Kepler's Law, tells us this?Explanation / Answer
9. All planets move in elliptical orbits, with the sun at one focus. This is Kepler's first law , "law of orbits".
10.The model tells that, a planet’s orbital speed changes, depending on how far it is from the Sun. The closer a planet is to the Sun, the stronger the Sun’s gravitational pull on it, and the faster the planet moves. The farther it is from the Sun, the weaker the Sun’s gravitational pull, and the slower it moves in its orbit.
This is described by the Kepler's second law, "Law of areas". It shows that , when the planet is closer to the sun, it moves faster, sweeping through a longer path in a given time.