1. Phys 150 Lecture 71 Please sit together in pairs: –Onyema and Michael –Alejandra and Honglu –Chris and Matt –Ryan and Lin –John F. and Anwen –Walter and Mengyue –Max and Melissa –Amanda and Zhongyun –Pauline and Kaijun –Jake and Erich –John W. and Irfan –Jennifer and Jason –Alexandra and Jiayuan –David and Erica –Abigael and Dian

2. Phys 150 Lecture 72 Announcements Homework 4 is due on Sunday at midnight. Quiz on Chapter 4 on Tuesday.

3. Phys 150 Lecture 83 Rocket fuel > 20 x Payload weight 3 stage liftoff Solid Rocket Booster (SRB) Booster Engine (RD180) ATLAS V launch 2011 Payload Fairing Centaur Main Engine

4. Phys 150 Lecture 84 i>clicker question The Centaur Main Engine is fueled by A.Plutonium B.Jet fuel C.Kerosene and Oxygen D.Hydrogen and Oxygen

5. Phys 150 Lecture 85 i>clicker question The Centaur Main Engine is fueled by A.Plutonium B.Jet fuel C.Kerosene and Oxygen – Booster engine D.Hydrogen and Oxygen

6. Phys 150 Lecture 86 Newton’s Third Law Forces always come in pairs –Every “action” has an equal and opposite “reaction” Cart

7. Phys 150 Lecture 87 Newton’s Third Law Forces always come in pairs –Every “action” has an equal and opposite “reaction” Cart Curiosity

8. Phys 150 Lecture 88 i>clicker question LEO velocity corresponds to about how much kinetic energy per gram? (Gasoline has about 10 Cal/gram of chemical energy.) A.7 Cal/gram B.700 Cal/gram C.70,000 Cal/gram D.7 Million Cal/gram

9. Phys 150 Lecture 89 i>clicker question LEO velocity corresponds to about how much kinetic energy per gram? (Gasoline has about 10 Cal/gram of chemical energy.) A.7 Cal/gram B.700 Cal/gram C.70,000 Cal/gram D.7 Million Cal/gram - Most (97%) of the chemical energy in a rocket launch is wasted!

10. Phys 150 Lecture 810 Space elevator

11. Phys 150 Lecture 811 Space elevator Carbon nanotube –nanometer = 1 billionth meter = 0.000000001 meters = 10 -9 meters

12. Phys 150 Lecture 812 i>clicker question One problem with simply firing a spaceship into orbit at LEO velocity (with a rail gun, for example) is A.the very high cost B.the very high forces involved C.the enormous energy required D.the enormous power required

13. Phys 150 Lecture 813 i>clicker question The biggest problem with simply firing a spaceship into orbit at LEO velocity (with a rail gun, for example) is A.the very high cost B.the very high forces involved C.the enormous energy required D.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

14. Phys 150 Lecture 814 i>clicker question Jet airplanes fly by A.pushing air upwards B.pushing air downwards C.pushing air backwards D.All of the above

15. Phys 150 Lecture 815 i>clicker question Jet airplanes fly by A.pushing air upwards B.pushing air downwards C.pushing air backwards D.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

16. Phys 150 Lecture 816 i>clicker question A Helium balloon floats because A.Helium is hotter than air B.Helium is at higher pressure than air C.Helium is at lower pressure than air D.Helium atoms are lighter than air molecules

17. Phys 150 Lecture 817 i>clicker question A Helium balloon floats because A.Helium is hotter than air B.Helium is at higher pressure than air C.Helium is at lower pressure than air D.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 ( 4 He vs. 14 N and 16 O)

18. Phys 150 Lecture 818 i>clicker question A Helium balloon rises until it reaches the altitude where A.the tropopause lies B.the air density is the same as the Helium density C.the air pressure is the same as the Helium pressure D.the air temperature is the same as the Helium temperature

19. Phys 150 Lecture 819 i>clicker question A Helium balloon rises until it reaches the altitude where A.the tropopause lies B.the air density is the same as the Helium density C.the air pressure is the same as the Helium pressure D.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.

20. Phys 150 Lecture 820 Lawnchair Larry – 1982

21. Phys 150 Lecture 821 i>clicker question Hot air rises because A.it is hotter than the atmosphere B.it is at lower pressure than the atmosphere C.it is less dense than the atmosphere D.All of the above

22. Phys 150 Lecture 822 i>clicker question Hot air rises because A.it is hotter than the atmosphere B.it is at lower pressure than the atmosphere C.it is less dense than the atmosphere D.All of the above - Atmosphere at Earth’s surface is 1 kg/m 3 - Atmospheric pressure is due to weight of air above - Warm air is less dense, thus lower atmospheric pressure - Moving warm air is called convection

23. Phys 150 Lecture 823 Thunderstorm and tropopause

24. Phys 150 Lecture 824 Hurricane Rotating stool

25. Phys 150 Lecture 825 Storm surge