Waves and Sound in Life Sciences PDF

 MECHANICS BY DR. ADEL MORAD Wave — A disturbance that propagates and transfers energy in the direction of propagation through matter or space. — Most waves move through a matter called a medium. Ø Ex. Waves traveling through water. Ø Wave motion: it is a periodic motion produced as...

 MECHANICS BY DR. ADEL MORAD Wave — A disturbance that propagates and transfers energy in the direction of propagation through matter or space. — Most waves move through a matter called a medium. Ø Ex. Waves traveling through water. Ø Wave motion: it is a periodic motion produced as a result as the vibration of the medium particles at a certain moment and in a definite direction.  TYPES OF WAVES — Waves are classified into different types according to their natures : WAVES Mechanical waves Electromagnetic waves Transverse waves Longitudinal waves Transverse waves TYPES OF WAVES  TYPES OF WAVES Mechanical Electromagnetic e.g. Water waves, seismic waves, e.g. Radio, X-Rays, Light waves on a rope, sound (waves caused by the disturbance in electric and magnetic fields ) Must have a substance to travel Do not need a substance to travel through through Cannot travel in a vacuum Can travel in a vacuum Vibrations passed on from Travel at very fast speed in a molecule to molecule vacuum: 3 × 108 m/s Waves can be transverse, Waves will only be transverse longitudinal , or surface waves What do Waves Do? — When waves travel through media, they are doing work (energy transferred). — Ex. Sound traveling in your ear causes vibrates throughout your ear Pascal’s Law 𝐹"#$ = &'() 𝐹,- &*+ (Tympanic Membrane)  What do Waves Do? — Ex. Shock waves move the earth during an earthquake. — Ex. Tsunami waves move anything in their path  How a Wave Travels —As wave travels in air, the waves spread out in spheres —the sphere will get bigger and bigger as they move farther away Wave Vibration Types — 1. Transverse Waves: Particles move perpendicular to the motion of the wave (Light waves, a ripple on a pond) — 2. Longitudinal Waves: Particles move parallel to the motion of the wave (Sound waves) Sine curve Energy transport 3. Standing Waves and Resonance Standing wave is a wave in which the amplitude at a given location does not vary with time. Standing Wave Features: — Amplitude is zero at fixed ends — Nodes (other places with zero amplitude) regions of no vibrations — Anti-nodes (places with maximum amplitude) regions of maximum vibration  Wave Diagram Wavelength Crest Amplitude Trough Wavelength  Wave Properties/concepts — 1. Wavelength λ -measures the size of the wave (distance between 2 successive crests/troughs or between the centers of 2 successive compressions /rarefaction) — 2. Amplitude A: measures the intensity (strength) of the wave — 3. Frequency f=v/ λ -The number of complete waves that achieved/produced from the source per second f=1/T (hertz (Hz) = beat/sec) -Your radio dials are in megahertz — 4. Period (time) T=2π/ω, ω=2 π f -It is the time taken by a source to make a complete wave. T=1/f (seconds) — 5. Wave Speed v: The distance covered by a wave in one second v=λ/T= λ f Frequency, wavelength, and Period — Wavelength and period will increase when frequency decreases. — λ ↓, T, ↓, then f ↑ Example A piano string vibrates with a frequency of 264 Hz. If the waves have a wavelength of 1.3 m, what is the speed of sound in air? Solution v= λ f speed= (1.30 m) (264 Hz) speed = 343 m/s Example A string with a wavelength of 1.30 m and a period of 0.00379 s is played. What is the speed of the wave? Solution v = λ/T speed=(1.30 m) / (0.00379 s) speed = 343 m/s  Mechanical Wave Speed These waves travel fastest in solids and the slowest in gases ='>?@A) — 𝑀𝑎𝑐ℎ number (Ma) = , s.t. 𝑣E"#-F = 343 m/s= 1,235 km/h, =B'(+C (kilometre in 2.9 seconds). sonic boom Regime Subsonic Transonic Speed of sound Supersonic Hypersonic Hypervelocity Mach 8.8