Please sit together in pairs: Mike A. and Heran Barney and Joe Serruto Thomas and Yiran

Mikhail and Grant • Valerie and Evan • Kevin and Rebecca • Ally and Katherine • Matt M. and Joe Sebek • Morgan and Quanbiao • Laura and Charlie • Lauren and Lu • Mikey O. and Ashkan • Hannah and Naichen • Jim and Dale • Nick and Disha • Ben and Efrain • Nik and Da • Please sit together in pairs: • Mike A. and Heran • Barney and Joe Serruto • Thomas and Yiran • Glenn and Steve T. • Ann and Joey B. • Johnny and Andrea • Korey and Stephen H. • Will and Qihan • Michael W. and Nicole • Zach and Ed • Casey and Zhenmin • Audrey and Taehoon • Lisette and Shenheng • Erica and Matt R. Phys 150 Lecture 14

Announcements • Homework 7 is due on Monday, Oct. 22 at midnight. • Quiz on Chapter 8 on Tuesday, Oct. 23. Phys 150 Lecture 14

Waves • Sound is a pressure (or density) wave Bell in vacuum Slinky Waves Phys 150 Lecture 14

i>clicker question Sound travels faster in air that is • warmer • cooler • higher density • lower density Phys 150 Lecture 14

i>clicker question Sound travels faster in air that is • warmer • cooler • higher density • lower density - Sound travels slower in cooler air  sound bends towards cooler air Marching band Phys 150 Lecture 14

i>clicker question During a temperature inversion • it is eerily quiet. • it is unusually noisy. • sound reflects off the earth. • sound escapes into space. Phys 150 Lecture 14

i>clicker question During a temperature inversion • it is eerily quiet. • it is unusually noisy. • sound reflects off the earth. • sound escapes into space. • Temperature inversion: cool at the ground, hotter above • Sound is bent back towards ground Phys 150 Lecture 14

i>clicker question The stratosphere is hot because • it is polluted with CFC’s. • of the greenhouse effect. • it is bombarded with cosmic rays. • Ozone absorbs UV sunlight. Phys 150 Lecture 14

i>clicker question The stratosphere is hot because • it is polluted with CFC’s. • of the greenhouse effect. • it is bombarded with cosmic rays. • Ozone absorbs UV sunlight. • Ozone = O3 - absorbs ultraviolet (UV) sunlight • Oxygen = O2 • CFC = Chlorofluorocarbon – catalyze O3 O2 Phys 150 Lecture 14

i>clicker question The sound channel in the atmosphere is located • in the stratosphere. • above the stratosphere. • near the tropopause. • near the stratopause. Phys 150 Lecture 14

Project Mogul Phys 150 Lecture 14

Speed of sound • Air 1000 ft/sec (330 m/sec) • Water 1 mi/sec • Steel 3.6 mi/sec Phys 150 Lecture 14

i>clicker question Sound travels faster in water that is • warmer • cooler • higher pressure • Both A. and C. Phys 150 Lecture 14

i>clicker question Sound travels faster in water that is • warmer • cooler • higher pressure • Both A. and C. • Ocean sound channel – warmer water above, higher pressure water below • SOFAR – hollow metal ball that implodes at depth of sound channel Humpback whale Phys 150 Lecture 14

i>clicker question A tsunami is a • longitudinal wave • transverse wave • surface wave • All of the above Phys 150 Lecture 14

i>clicker question A tsunami is a • longitudinal wave • transverse wave • surface wave – has elements of both longitudinal and transverse waves • All of the above • Water waves: v ≈ π√D if L > D (“shallow wave”) • D = depth of water L = wavelength • Tsunami wavelength: 10 – 100 km Waves Japanese tsunami 2011 (1) Japanese tsunami 2011 (2) Phys 150 Lecture 14

Please sit together in pairs: Mike A. and Heran Barney and Joe Serruto Thomas and Yiran