Download presentation

Presentation is loading. Please wait.

Published byBritton McGee Modified about 1 year ago

1
Lecture 7 ASTR 111 – Section 002

2
Reading Chapter 4.4 and 4.5

3
Outline 1.Exam 1 Discussion 2.Finish material in last lecture 3.Kepler’s laws

4
First Exam 9/29 (Tuesday). Based on lecture notes, problems worked in lecture, and quizzes. (Chapters 1 through 4.5 have more details on these subjects.) Approximately 50 questions. In the Testing and Tutoring Center in Sub II (Student Union Building II) Exam will be administered via Blackboard system. You may bring a non-scientific calculator! You have 75 minutes to complete the exam.

5
Outline 1.Exam 1 Discussion 2.Finish material in last lecture 3.Kepler’s laws

6
Outline 1.Exam 1 Discussion 2.Finish material in last lecture 3.Kepler’s laws

7
Kepler proposed elliptical paths for the planets about the Sun Using data collected by Brahe, Kepler deduced three laws of planetary motion: 1. the orbits are ellipses 2. a planet’s speed varies as it moves around its elliptical orbit 3.the orbital period of a planet is related to the size of its orbit

8
Text these numbers

9
Abbreviation Circle with radius 1.0 x goes from -1.0 to 1.0 in steps of 0.1. Compute y using

10
Equation for a circle

11
Equation for an ellipse

12
How would you convince someone that this is an ellipse?

13
b=2 a=7

14
If it were an ellipse, this would always be true

16
Is this an ellipse? 10 ?

17
Kepler’s First Law = a b Planets orbit the Sun in an ellipse

18
Kepler’s Second Law

19
Kepler’s Third Law

20
Sidereal Review

21
Kepler’s Laws Planet orbit is ellipse Equal area in equal time Farther away planets orbit slower

22
Suppose that you are looking down on a solar system with one planet orbiting a star. You take a picture every 10 days. 1.Does this planet obey Kepler’s laws? How do you know? 2.How would the speed of this planet change? How would you measure the change in speed? #1 #2 #3 #4 #5 #6 #7 #8 #9 #10 #11 #12 Based on Lecture-Tutorials for Introductory Astronomy 2 nd ed., Prather et. al, page 21

23
The following planet obeys Kepler’s second law. 3.Draw two lines: one connecting the planet at Position A to the star and a second line connecting the planet at Position B to the star. Shade in the triangular area swept out by the planet when traveling from A to B. 4.Which other two planet positions, out of C-I, could be used together to construct a second swept-out triangular area that would have approximately the same area as the one you shaded in for Question 3? Shade in the second swept-out area using the planet positions that you chose. Note: Your triangular area needs to be only roughly the same size; no calculations are required. 5.How would the time it takes the planet to travel from A to B compare to the time it takes to travel between the two positions you selected in the previous questions? Explain your reasoning! 6.During which of the two time intervals for which you sketched the triangular areas in questions 3 and 4 is the distance traveled by the planet greater? 7.During which of the tow time intervals for which you sketched the triangular areas in Questions 3 and 4 would the planet be traveling faster? Explain your reasoning!

24
I A B C D E F G H

25
8.The drawing on the following slide shows another planet. In this case, the twelve positions are exactly one month apart. As before, the plane obeys Kepler’s second law. 9.Does the planet appear to be traveling the same distance each month? 10.At which position would the planet have been traveling the fastest? The slowest? Explain your reasoning. 11.At position D, is the speed of the planet increasing or decreasing? Explain. 12.Provide a concise statement that describes the relationship that exists between a planet’s orbital speed and the planet’s distance from its companion star.

26
I A B C D E F G H J K L

Similar presentations

© 2017 SlidePlayer.com Inc.

All rights reserved.

Ads by Google