1. Phys 150 Lecture 31 Please sit together in pairs: –Onyema and Honglu –Alejandra and Matt –Chris and Lin –Ryan and Anwen –John F. and Mengyue –Walter and Melissa –Max and Zhongyun –Amanda and Kaijun –Pauline and Erich –Jake and Irfan –John W. and Jason –Jennifer and Jiayuan –Alexandra and Erica –David and Dian –Abigael and Michael

2. Phys 150 Lecture 32 Announcements Chapters 1 and 2 are available online (see the 150 web page) Homework 2 is due on Sunday, Jan 27, at midnight. Quiz on Chapter 2 on Tuesday, Jan 29. i>clickers are required starting today. Please register via the 150 web page.

3. Where is this? Phys 150 Lecture 33

4. Where is this? Phys 150 Lecture 34 Business Instructional Facility (BIF)

5. Phys 150 Lecture 35 Hydrogen Fuel Cell 2 H 2 + O 2 = 2 H 2 O + energy A fuel cell is like a battery that can be replenished with more chemicals

6. Phys 150 Lecture 36 i>clicker question Most of the Hydrogen we use for power comes from A.Pockets of Hydrogen gas found underground B.Hydrogen gas extracted from the atmosphere C.Hydrogen produced in nuclear reactors D.Hydrogen manufactured from fossil fuels and/or water

7. Phys 150 Lecture 37 i>clicker question Most of the Hydrogen we use for power comes from A.Pockets of Hydrogen gas found underground B.Hydrogen gas extracted from the atmosphere C.Hydrogen produced in nuclear reactors D.Hydrogen manufactured from fossil fuels and/or water

8. Phys 150 Lecture 38 Hydrogen Fuel Cell 2 H 2 + O 2 = 2 H 2 O + energy Energy + 2 H 2 O = 2 H 2 + O 2 Electrolysis

9. Phys 150 Lecture 39 Hydrogen Fuel Cell 2 H 2 + O 2 = 2 H 2 O + energy Energy + 2 H 2 O = 2 H 2 + O 2 Energy + 2 H 2 O + CH 4 = 4 H 2 + CO 2 Electrolysis CH 4 = methane

10. Phys 150 Lecture 310 Hydrogen Fuel Cell 2 H 2 + O 2 = 2 H 2 O + energy Energy + 2 H 2 O = 2 H 2 + O 2 Energy + 2 H 2 O + CH 4 = 4 H 2 + CO 2 Hydrogen is not a source of energy. It is only a means of transporting energy. Electrolysis CH 4 = methane

11. Phys 150 Lecture 311 Hydrogen Fuel Cell 2 H 2 + O 2 = 2 H 2 O + energy Energy + 2 H 2 O = 2 H 2 + O 2 Energy + 2 H 2 O + CH 4 = 4 H 2 + CO 2 Hydrogen is not a source of energy. It is only a means of transporting energy. but Electrolysis H 2 has 3x more energy per gram than gasoline H 2 (compressed gas) has 6x less energy per gallon than gasoline CH 4 = methane

12. Phys 150 Lecture 312 i>clicker question One difference between Hybrid autos and Electric autos is A.Hybrids use cheap batteries, Electrics use expensive batteries B.Hybrids use expensive batteries, Electrics use cheap batteries C.Electrics use the battery to power the car, Hybrids do not D.Hybrids use small batteries, Electrics use large batteries

13. Phys 150 Lecture 313 i>clicker question One difference between Hybrid autos and Electric autos is A.Hybrids use cheap batteries, Electrics use expensive batteries B.Hybrids use expensive batteries, Electrics use cheap batteries C.Electrics use the battery to power the car, Hybrids do not D.Hybrids use small batteries, Electrics use large batteries

14. Phys 150 Lecture 314 Hybrid and Electric Vehicles Electric vehicles: batteries only –Nissan Leaf Hybrid vehicles: gasoline plus batteries –Toyota Prius PHEV: Plug-in Hybrid Electric Vehicles –Chevy Volt Expensive batteries have about 100 times less energy per gram than gasoline Expensive batteries cost about $50/lb

15. Phys 150 Lecture 315 i>clicker question Hybrid autos are more energy efficient than standard autos because A.the batteries are recharged when braking B.the batteries are recharged when going downhill C.the engine is more efficient when running on electricity D.All of the above

16. Phys 150 Lecture 316 i>clicker question Hybrid autos are more energy efficient than standard autos because A.the batteries are recharged when braking B.the batteries are recharged when going downhill C.the engine is more efficient when running on electricity D.All of the above A.instead of heating up brakes B.capturing gravitational energy C.85% efficient vs. 20% efficient D.Hybrids also turn off the engine when idling

17. Hybrid vs Conventional Conventional (C) –$23,700 price tag –($3.50/gal) / (28 miles/gal) = 12.5 cents/mile Hybrid (H) –$27,200 price tag –($3.50/gal) / (47 miles/gal) = 7.5 cents/mile Cost for 100,000 miles of driving C: $23,700 + $0.125 cents/mi x 100,000 mi = $36,200 H: $27,200 + $0.075 cents/mi x 100,000 mi = $34,700 Phys 150 Lecture 317

18. Phys 150 Lecture 318 Types of Energy Chemical energy Heat energy = Thermal energy Kinetic energy = energy of motion = ½ mv 2 Electric energy Light energy Nuclear energy ≈ 10 6 x chemical energy Gravitational energy