PHYS 105 1nd EditionExam # 1 Study Guide Lectures: 1 - 11Week 1 What is acoustics?- Acoustics are the science of sound What are the two types of waves and what do they transport?- Longitudinal and transverse waves and they transport information and energyWhat type of wave is a sound wave and how are they produced?- They are longitudinal waves and they are produced by the mechanical vibration of objects Compare kinetic and potential energy.- Kinetic Energy: Energy is dependent on a moving body- Potential Energy: Energy is dependent on the position What is conservation energy?- Total mechanical energy is conserved if there is no friction involved *** All formulas used to solve velocity or displacement will be provided on given formula sheetWeek 2What is simple harmonic motion?- The relationship between a restoring force and the displacement of the system from the equilibrium position is linear Describe resonance.- The existence of a natural frequency of any oscillating system What is dampening in a system?- When there is friction force in an oscillator, the oscillation is gradually dampedWhat type of functions can you use to describe a simple harmonic motion wave?- Sine and cosine What does a vibration spectrum display?- It displays periodic motion through complex vibrating systems. Electronic instruments called spectrum analyzers are commonly used to extract spectrum of a complex wave. Week 3 What is a wave?- It is a disturbance to a medium that can transport energy and information from one location to another What are the two types of waves and what makes them different?- Transverse: The medium vibration is perpendicular to the direction of the wave propagation - Longitudinal: The medium vibrates in the direction parallel to the direction of the wave propagation Describe wave superposition and interference - When there are two waves, you sum up their amplitudes and they can either interfere constructively or destructively. Adding up incident and reflected waves when they overlap. How are pitch and loudness described in terms of physics?- Pitch is associated with frequency and loudness is associated with amplitudeWhat s the inverse square law?- When the sound wave from a point source radiates outward uniformly over a sphereWhat is the Doppler Effect?- It is the apparent shift in frequency observed with the source/observer is in relative motion. When they are moving towards each other, the frequency appears higher and when they are moving away from each other, the frequency appears lower. o Think of an ambulance siren moving towards and away from you. Compare reflection, diffraction and refraction and note the differences.- Reflection: Wave reflection from a curved barrier can be focused onto a point o Wave reflected from a fixed end has a 180 deg. phase shift and waves reflected from an open-end does not have a phase shift at all. - Refraction: Waves travel through different medium with different wave speed will change direction of travel - Diffraction: When waves encounters obstructions, it can bend around the obstacle or pass through a narrow opening Week 4What is a standing wave and where are the regions of a node vs. an anti-node?- A standing wave is when the incoming and the reflective waves can interfere to produce “standing wave modes” or “resonances” on the string. Standing waves has regions of minimum amplitude called ‘nodes’ and regions of maximum amplitudes called ‘anti-nodes’ What is sound pressure and what simple harmonic motion is it similar to?- It is force per unit area and it is the pressure exerted by the sound wave and it is similar to the SHM of a spring systemIs it a free or fixed end for the pressure disturbance at the open end of a pipe?- Fixed endIs it a free or fixed end for the pressure disturbance at the closed end of a pipe?- Free end The frequency with n=1 is called the fundamental frequency, what are all the higher frequenciescalled?- Harmonics Find the first three modes of vibration for an open-open pipe that is .75 m long.- 229 Hz, 460 Hz and 690 Hz - Solve by: 343/2(.75) for first mode and then multiply by 2 and 3 to solve for the 2nd and 3rd