March 31

1. March 31 A Day – Geo – Wrapping Up Ch. 12

2. DO NOW – write in your notes!(Turn in your Book HW) • The Moon has a radiusthat is approx. 0.27 that of Earth’s, and a massthat is approx. 0.012that of Earth’s. Would you weigh more or less on the Moon, and by what factor? • Mars has a radiusthat is approx. ½that of Earth’s, and a massthat is approx. 0.1 that of Earth’s. Would you weigh more or less on Mars, and by what factor? • The Sun has a radiusthat is approx. 100times that of Earth’s, and a massthat is approx. 333,000that of Earth’s. Would you weigh more or less on the Sun, and by what factor?

3. DO NOW – write in your notes!(Turn in your Book HW) • The Moon has a radiusthat is approx. 0.27 that of Earth’s, and a massthat is approx. 0.012that of Earth’s. Would you weigh more or less on the Moon, and by what factor? • Mars has a radiusthat is approx. ½that of Earth’s, and a massthat is approx. 0.1 that of Earth’s. Would you weigh more or less on Mars, and by what factor? • The Sun has a radiusthat is approx. 100times that of Earth’s, and a massthat is approx. 333,000that of Earth’s. Would you weigh more or less on the Sun, and by what factor? 0.16 times what you would weigh on Earth 0.4 times what you would weigh on Earth 33 times what you would weigh on Earth

5. 4x more For BOTH problems!

6. Yes Your weight Your Mass Earth’s Mass Distance b/t you and center of Earth

7. Answers for # 3 – 7 – NOT in order 1/9 as much 8x more 4x more The same 3x more

8. Challenge #8. 2.33 x 10-6 N #9. 1.75 x 1020 N

9. Look at your Lab - Check #18-25!! When you’re done, Check the HW due LAST CLASS - #8-12

10. Look at your Lab:Check #18-25!! – NOT in order • ½ as much • Directly proportional • 1/16 as much • 4x as much • 3x as much • 2x as much • ¼ as much • Inversely proportional to the square

11. Answers for HW due last class: #8-12– NOT in order • Gravity is REALLY weak!!! • As the distance increases, gravity decreases by the inverse square of the distance • Gravity is universal – it’s everywhere – it’s not unique to Earth • 1/25 as much (4% the weight); 1/100 as much (1% the weight) • Your mass, earth’s mass, and the distance between you and the center of earth

12. POST LAB • Go to your test seats • Cell phones out and on silent • You may use your notes • Complete the Post Lab (open notes) & turn in (no extra credit) • When you are done, you can silently return to your test seats and complete work for another class, read a book, use your phone, etc.

13. FIX THIS!!!

14. POST LAB • Go to your test seats; Cell phones out and on silent; You may use your notes • Complete the Post Lab (open notes) & turn in (no extra credit) • You MIGHT repeat answers, OR MAYBE NOT! • The answer banks can have repeated answers • When you are done, you can silently return to your test seats and START YOUR HW (see the white board)… or complete work for another class, read a book, use your phone, etc.

15. Review Game – Team Quiz • Groups of 1 – 4 (Team Quiz) • Out of 6 points (like a HW grade). • 1 point per problem correct… • BUT extra credit can be earned for every correct question in addition to first 6. • Potential for 13/6 on this!!! • Spread out so other teams can’t hear you. • 1 sheet of loose leaf per team • All team member names & ID’s at the top • # each answer (you only need to write answers, not questions) • If your answer is unclear, no credit will be earned! • Be COMPLETE in your answer – give as MUCH DETAIL as possible! (Do not need to use full sentences)

16. 1. Gravitational force is always attractive / repulsive.

17. 2. Gravitational force exists everywhere / only in some places in the universe

18. 3. TRUE or FALSE or NOT ENOUGH INFO…EXPLAIN : Space shuttle astronauts are weightless because there is no gravity above Earth 

19. 4. If a gravitational force exists between two objects, one very massive and one less massive, then the force on the less massive object will be greater than/ equal to / less than the force on the more massive object.

20. 5. As the distance between masses decreases, force increases / decreases.

21. 6. Venus is called Earth’s “sister” planet because it is almost the same size (mass & diameter) as Earth. BUT – Venus is closer to the Sun. Does the Sun have a STRONGER or WEAKER gravitational pull on Venus than it does on Earth? EXPLAIN:

22. 7. The earth’s gravity is pulling on you. Are you pulling on the earth? And if so, which force is stronger – earth pulling you, or you pulling earth? Explain your reasoning.

23. 8. Gravity is a force of attraction between objects based on their mass and their distance apart. Why aren’t other objects, like your pencil, being pulled towards you? Explain your reasoning.

24. Why do you think the Earth orbits the sun, not the other way around (sun orbiting Earth?? ) Use what you have learned this chapter and PREVIOUSLY to EXPLAIN!!!

25. 10. Consider a pair of binary stars that pull on each other with a certain force. Would the force be larger or smaller if the mass of each star were three times as great & their distance apart is three times as far? • Show what the new force will be compared to the first one… show MATHEMATICAL REASONING … SHOW YOUR WORK! • (*Binary Stars are ‘twin’ stars that are locked in the same circular orbit)

26. 11. show MATHEMATICAL REASONING … • SHOW YOUR WORK!

27. 12. TRUE or FALSE or NOT ENOUGH INFO…EXPLAIN: Planets very far away from the sun exert less gravity than Earth exerts  

28. 13. TRUE or FALSE or NOT ENOUGH INFO…EXPLAIN: Planets with thin atmospheres (or no atmospheres!) have very little to no gravity