Please sit together in pairs: Mike A. and Yiran Barney and Steve T. Thomas and Joey B.

1. Arielle and Evan • Mikhail and Rebecca • Valerie and Katherine • Kevin and Joe Sebek • Ally and Quanbiao • Matt M. and Charlie • Morgan and Lu • Laura and Ashkan • Lauren and Naichen • Mikey O. and Dale • Hannah and Disha • Jim and Efrain • Nick and Da • Ben and Heran • Nik and Joe Serruto • Please sit together in pairs: • Mike A. and Yiran • Barney and Steve T. • Thomas and Joey B. • Glenn and Johnny • Ann and Stephen H. • Meaghan and Qihan • Korey and Nicole • Will and Ed • Michael W. and Zhenmin • Zach and Taehoon • Casey and Shenheng • Audrey and Matt R. • Lisette and Andrea • Erica and Grant Phys 150 Lecture 6

2. Announcements • Homework 3 due on Monday at midnight. • Quiz on Chapter 4 on Tuesday in class. Phys 150 Lecture 6

3. Rocket fuel > 20 x Payload weight Payload Fairing Centaur Main Engine Solid Rocket Booster (SRB) Booster Engine (RD180) 3 stage liftoff ATLAS V launch 2011 Phys 150 Lecture 6

4. i>clicker question The Centaur Main Engine is fueled by • Plutonium • Jet fuel • Kerosene and Oxygen • Hydrogen and Oxygen Phys 150 Lecture 6

5. i>clicker question The Centaur Main Engine is fueled by • Plutonium • Jet fuel • Kerosene and Oxygen – Booster engine • Hydrogen and Oxygen Phys 150 Lecture 6

6. Newton’s Third Law • Forces always come in pairs • Every “action” has an equal and opposite “reaction” Cart Phys 150 Lecture 6

7. Newton’s Third Law • Forces always come in pairs • Every “action” has an equal and opposite “reaction” Cart Curiosity Landing 2012 Phys 150 Lecture 6

8. i>clicker question LEO velocity corresponds to about how much kinetic energy per gram? (Gasoline has about 10 Cal/gram of chemical energy.) • 7 Cal/gram • 700 Cal/gram • 70,000 Cal/gram • 7 Million Cal/gram Phys 150 Lecture 6

9. i>clicker question LEO velocity corresponds to about how much kinetic energy per gram? (Gasoline has about 10 Cal/gram of chemical energy.) • 7 Cal/gram • 700 Cal/gram • 70,000 Cal/gram • 7 Million Cal/gram - Most (97%) of the chemical energy in a rocket launch is wasted! Phys 150 Lecture 6

10. Space elevator Phys 150 Lecture 6

11. Space elevator • Carbon nanotube • nanometer = 1 billionth meter • = 0.000000001 meters = 10-9 meters Phys 150 Lecture 6

12. i>clicker question One problem with simply firing a spaceship into orbit at LEO velocity (with a rail gun, for example) is • the very high cost • the very high forces involved • the enormous energy required • the enormous power required Phys 150 Lecture 6

13. i>clicker question The biggest problem with simply firing a spaceship into orbit at LEO velocity (with a rail gun, for example) is • the very high cost • the very high forces involved • the enormous energy required • the enormous power required - A one kilometer rail gun produces 3200 g’s! - Compare to a commercial airline’s ¼ g’s - Human’s can tolerate at most 10 g’s (for a short time) - Astronauts experience at most 3g’s Phys 150 Lecture 6

14. i>clicker question Jet airplanes fly by • pushing air upwards • pushing air downwards • pushing air backwards • All of the above Phys 150 Lecture 6

15. i>clicker question Jet airplanes fly by • pushing air upwards • pushing air downwards • pushing air backwards • All of the above - Newton’s third law: pushing air downwards pushes plane upwards - Same for helicopters - The jet (or propeller) pushes the plane forwards to overcome air resistance – the same as a car. Palm helicopter Phys 150 Lecture 6

16. i>clicker question A Helium balloon floats because • Helium is hotter than air • Helium is at higher pressure than air • Helium is at lower pressure than air • Helium atoms are lighter than air molecules Phys 150 Lecture 6

17. i>clicker question A Helium balloon floats because • Helium is hotter than air • Helium is at higher pressure than air • Helium is at lower pressure than air • Helium atoms are lighter than air molecules - The number of molecules per volume of a gas is the same (at the same temperature and pressure) - Helium atoms are light (4He vs. 14N and 16O) Phys 150 Lecture 6

18. i>clicker question A Helium balloon rises until it reaches the altitude where • the tropopause lies • the air density is the same as the Helium density • the air pressure is the same as the Helium pressure • the air temperature is the same as the Helium temperature Phys 150 Lecture 6

19. i>clicker question A Helium balloon rises until it reaches the altitude where • the tropopause lies • the air density is the same as the Helium density • the air pressure is the same as the Helium pressure • the air temperature is the same as the Helium temperature - It’s the density that matters. - You can’t fly a balloon into space because there is no atmosphere in space. Phys 150 Lecture 6

20. Lawnchair Larry – 1982 Phys 150 Lecture 6

21. i>clicker question Hot air rises because • it is hotter than the atmosphere • it is at lower pressure than the atmosphere • it is less dense than the atmosphere • All of the above Phys 150 Lecture 6

22. i>clicker question Hot air rises because • it is hotter than the atmosphere • it is at lower pressure than the atmosphere • it is less dense than the atmosphere • All of the above - Atmosphere at Earth’s surface is 1 kg/m3 - Atmospheric pressure is due to weight of air above - Warm air is less dense, thus lower atmospheric pressure - Moving warm air is called convection Phys 150 Lecture 6

23. Thunderstorm and tropopause Phys 150 Lecture 6

24. Hurricane Rotating stool Phys 150 Lecture 6

25. Storm surge Phys 150 Lecture 6