-Mechanical wave-disturbance transmitted by a medium form from one point to another, without the medium itself being transported Transverse Traveling Waves: -A transverse wave travels (propogates) in a direction perpendicular to the direction in which the median is vibrating. Basically the wave oscillates perpendicular to it’s direction of travel. -Crests-maximum vertical displacement above the horizontal -Troughs-maximum vertical displacement below the horizontal -Wavelength-the crests and troughs repeat themselves at regular intervals along the rope, and the distance between two adjacent crests (or two adjacent troughs) is the length of one wave -Amplitude of the wave -maximum displacement from the horizontal equilibrium position of the rope is measurable -The direction in which the rope oscillates (vertically) is perpendicular to the direction in which the wave propagates (or travels, horizontally), this wave is transverse. -Period-The time it takes for one complete vertical oscillation of a point on the rope -Frequency-the number of cycles it completes in one seconds, f -The period and frequency are reestablished by the source of the wave, T= 1/f Wave Speed on a Stretched String: BIG WAVE RULES: -The speed of a wave is determined by the type of wave and the characteristics of the medium, not by the frequency -When a wave passes into another medium, its speed changes, but its frequency does not. Superposition of Waves: -when two or more waves meet, the displacement at any point of the medium is equal to the algebraic sum of the displacements due to the individual waves -Constructive Interference-two waves have a displacement of the same sign when they overlap, and the combined wave will have a displacement of greater magnitude than either individual wave -Destructive Interference-the waves have opposite displacements when they meet, the combined waveform will have a displacement smaller magnitude than either individual wave -In phase-if crest meets crest and trough meets trough, then the waves will constructively interfere completely, and the amplitude of the combined wave will be the sum of the individual amplitudes -Out of phase-if crest meets trough and trough meets crest—then they will destructively interfere completely, and the amplitude of the combined wave will be the difference between the individual amplitudes. -Standing Wave-The crests and troughs no longer travel down the length of the string -While every point on the string had the same amplitude as the traveling wave went by, each point on a string supporting a standing wave as an individual amplitude. -The points marked N are called nodes, and those marked are called antinodes -Nodes and antinodes always alternate, they’re equally spaced, and the distance between two successive nodes (or antinodes) is equal to 1/2λ. -Used to determine how standing waves can be generated -The following figures show the three simplest standing waves that our string can support. -First standing wave has one antinode -Second wave has two antinode -Third wave has three antinodes -The length of the string in all three diagrams is L. To solve for the wavelength, we use: These are called the harmonic (or resonant) wavelengths, and the integer n is known as the harmonic number. Sound Waves ● Compressions-The variations in the conducting medium can be positions at which the molecules of the medium are bunched together (where the pressure is above normal) ● Rarefactions-positions where the pressure is below normal -Difference between sound waves and the waves we’ve been studying on stretched strings is that the molecules of the medium transmitting a sound wave more parallel to the direction of wave propagation, rather than perpendicular to it. -For this reason, sound waves are said to be longitudinal. -The speed of a sound wave depends on the medium through which it travels. In particular, it depends on the density (p) and on the bulk modulus (B), a measure of the medium’s response to compression -Sound generally travels faster through solids than through liquids and faster through liquids than through gas. Beats: Resonance for Sound Waves: -The Doppler Effect-When a source of sound waves and a detector are not in relative motion, the frequency that the source emits matches the frequency that the detector receives. -However, if there is relative motion between the source and the detector, then the waves that the detector receives are different in frequency (and wavelength).