Upcoming Deadlines Homework #10 Outline for Second Term Paper Due Tuesday, April 17 th (Next week) 10 points (5 points if late) Second Term Paper Science Fact or Cinematic Fiction? Due Tuesday, April 24 th (In two weeks) 100 points (50 points if late) For full schedule, visit course website: ArtPhysics123.pbworks.com Pick up a clicker, find the right channel, and enter Student ID Homework Assignment #10 Outline of your Second Term Paper. Topic: Science Fact or Cinematic Fiction? An important component of being a well-educated adult is the ability to distinguish between fact and fiction, between science and make-believe. For this assignment, you will choose a single physics principle, such as conservation of energy or the action/reaction principle, and describe three scenes from three different films that incorrectly illustrate that physics law or principle. Homework Assignment #10 For example, you can describe how the principle of action/reaction is violated during a fight sequence when one character recoils but without a matching reaction on the other character. The three films you select can be animated or live- action featuring CGI animation special effects. May also use video games or animated TV shows. You are strongly encouraged to find three scenes that are as different as possible from each other yet have the same fundamental error in the physics. Homework Assignment #10 Post your outline in a blog entry entitled, Outline for the Second Term Paper. Outline due by 8am on Tuesday, April 17th 10 points (if late, 5 points) The term paper itself is due a week later. Length, structure, grading rubric, etc. are similar to the first term paper. Optional: Do a video term paper(about 8 minutes) Reverse Video Reference Winners Twenty bonus points go to: Gil Franco Ryan Geery Sandra Kaminski Lauren Zucher Extra Credit Opportunity Attend any event at 55th San Francisco International Film Festival, April 19May 3, in San Francisco. Present proof of you attendance (receipt, photos, etc.) for 10 points of extra credit. Extra Credit Opportunity Attend any event at the 6th Annual San Francisco Bay Area International Children's Film Festival, April 2122, in downtown San Jose. Present proof of you attendance (receipt, photos, etc.) for 5 points of extra credit. For info:Childrens Discovery Museum Extra Credit Opportunity Turn in your ticket receipt for ten points extra credit. Hours: Wednesday-Monday: 10a.m.-6p.m Admission: $15.00 for students Location: 104 Montgomery Street Inside The Presidio of San Francisco Visit the Walt Disney Family Museum Extra Credit Opportunity Turn in your ticket receipt for ten points extra credit. Hours: Tuesday-Sunday: 10a.m.-5p.m Admission: $12.00 for students Location: 3601 Lyon Street, SF Next to Palace of Fine Arts complex Visit the Exploratorium in San Francisco. Survey Question How many extra credit assignments have you done so far? A)None B)One C)Two or Three D)Four or more Review Question Synchronized standing and sitting by a stadiums crowd is what type of wave? A.Lateral B.Transverse C.Longitudinal D.Invitational E.Transvestical Amplitude Wave Motion Transverse vs. Longitudinal Waves Wave Motion Amplitude Wave Motion Both types of waves can travel down a SlinkyB) Transverse Review Question When a buzzer is moving towards you the wavelength of the sound gets shorter. The frequency of the sound is A) Higher B) Lower C) Unchanged Shorter Wavelength Doppler Effect A) Higher If moving towards you, wavelength shorter and frequency higher. If moving away, wavelength longer and frequency lower. Waves & Sound Part II Explosions and Waves High Pressure Explosions produce pressure waves due to differences in pressure Explosion by Combustion Two types of combustion, classified by their speed: Deflagration Rate of combustion slower than the speed of sound. Most combustion is deflagration. Detonation Rate of combustion is faster than the speed of sound. Only with high explosives. Firecracker Candle Dynamite Atomic Bomb Combustion Waves Deflagration wave Sound of the explosion may be loud but is not a shock wave. Burn Sound Detonation wave Dangerous shock wave is produced by the blast Burn Sound Trinity Atomic Test Live-Action Pyrotechnics Gasoline Primary Bomb (Black powder) Ignition Bomb With Gasoline Without Gasoline Explosions in movies are commonly produced by blasting a balloon of gasoline into the air with one bomb and igniting the vapor with a secondary bomb. Demo: Flaming Pumpkin Blow Cloud of corn starch combusts rapidly due to the large amount of oxygen available to each grain. Example of a rapid deflagration. Demo: Flaming Pumpkin Animation of Dust Explosions From Animating Suspended Particle Explosions, B. Feldman, J. OBrien, O. Arikan, UC Berkeley, SIGGRAPH 2003 The animation algorithms for these explosions focus on creating a realistic fireball without a blast wave. Nuclear Blast Operation Upshot-Knothole (1953) Light from the blast sets houses on fire before blast wave hits. Intense force due to the high pressure shock wave. Even after the shock front passes there is a strong outward wind, causing further destruction. Survival Town Operation Teapot; Apple-2 Test (1955) 29 Kiloton yieldNotice how the pressure first jumps as the blast wave hits then reverses and causes a back pressure suction. Indiana Jones and the Kingdom of the Crystal Skull (2008)Indiana Jones implausibly survives a nuclear blast hiding inside a refrigerator. Demo: Shock Tube To vacuum pump Cap vacuum inside vacuum in front of ball Seal the tube and remove the air inside Open one end; air rushing in forms a shock wave behind the ball Ball is fired at high speed Shock wave (Mach 1.5) Natural Frequencies Metal baseball bat and wooden bat sound very different when dropped to the floor. Different materials and shapes vibrate at their own natural frequencies. Standing Waves When a wave interferes with its reflection, this may create a standing wave. Fundamental & Overtones The Fundamental is the lowest frequency standing wave. The Overtones are twice, three times, etc., the frequency of the Fundamental. 110 Hz (A 2 ) 220 Hz (A 3 ) 330 Hz (E 4 ) Frequencies of standing waves for a 6 foot long organ pipe Demo: Hoot Tubes Large tube has a metal screen near one end. Heat screen with a flame. Remove tube from the flame and it plays like an organ pipe. Hoot Tubes, Analyzed Remove the flame and hot air rises from the screen, drawing in cold air. Hot air rising through pipe causes vibration at natural frequency, which depends on the length of the pipe. Amplitude depends on the diameter of the pipe. FLAME Wave Spectrum To appreciate what it takes to create a realistic animation of water, such as the ocean, its useful to understand the concept of wave spectrum. Real CGI Spectral Decomposition A complicated wave pattern may be decomposed as a sum of simple waves. The graph of intensity (or power) versus frequency is the spectral decomposition. Time Amplitude Decomposition into waves Frequency Intensity Class Demo: Wave Spectrum Timbre and Spectrum A musical instrument playing a single note produces not just that notes frequency but others as well, mostly overtones. The frequencies produced by a flute playing an A (slightly flat) show that the fundamental (436 Hz) and the harmonic (872 Hz) have almost the same amplitude. The spectrum of a tuning fork has (mostly) a single peak at the fundamental. Why Instruments Differ The unique spectrum of frequencies for a musical instrument gives that instrument a unique signature, which is called the instruments timbre (or quality). Playing this note (196 Hz) Noises White noise has a spectrum with uniform intensity over a broad range of frequencies, in analogy with the spectrum of white light. By the same analogy, red noise is similar to white noise but with more power in lower frequencies (red light is lower frequency than green or blue). Intensity (dB) Frequency Time White Noise Spectrum Ocean Wave Spectrum High Frequency Short Wavelength Low Frequency Long Wavelength Intensity High Winds Low Winds As the wind speed increases, the intensity of the large surge waves increases dramatically while the short ripples increases much less. Waves and Scale Models The Poseidon Adventure (1972) Interview with the Vampire (1994) It is very difficult to make water waves look realistic using scale models due to the effects of surface tension, viscosity, etc. Timber of a Material Spectrum of waves will be different for different materials due to density, viscosity, surface tension, depth of the fluid, etc. Gushing Oil WellJello waves Oil on the Water Wave spectrum changes due to oil slick Exxon Valdez accident Media That Transmit Sound Sound travels better through elastic liquids and solids, such as water and rocks, than through air. This is due to the close proximity of the atoms as they vibrate. Sonar used by whale and dolphins Demo: Tin-can Telephone Vibrations in a material transmit waves, such as when sound is communicated along the string of in a tin can telephone. Demo: Wave Spectrum Strike the iron grate and listen to the sound. Next, loop the string loop on your finger and let the iron grate hang freely. Place your fingertips in your ears. Strike the iron grate again and listen to the difference in the sound. Hear richer, louder sound transmitted by string Quiz Question Your voice sounds different to you when you hear it from a recording. This is because when you are speaking aloud, most sound waves reach your ear traveling through the solid flesh and bone of your skull instead of through the air. True or False ? Leave yourself a voic What Your Voice Sounds Like True Low frequencies travel better through solid flesh and bone than in the air. Next Lecture Effects Animation Hot & Cold Homework 10 (Outline of 2 nd Term Paper) Due Tuesday, April 17 th (Next week) Please turn off and return the clickers!