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Periodic Motion
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motion in which the restoring force is directly proportional to the displacement (springs and pendulum)
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Hook's Law
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states that the force required to compress a spring by a distance is proprtional to the distance
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Hook's Law Equation
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F = -kd (k is the spring constant)
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PE of a spring
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PE = 1/2 x k x d2
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application of a simple pendulum
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to determine the gravitational acceleration
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Periodic Time
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T = 2(pi)√(L/g)
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Transversal Waves
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waves that oscillate perpendicularly to their direction of motion
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Longitudinal Waves
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waves that oscillate in the same direction as their motion
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Surface Waves
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waves that move perpendicularly and parallel to the direction of motion
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One dimesional wave
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ex: Rope
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Two dimensional Wave
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ex: water waves
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Three dimensional waves
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ex: sound and EM waves
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Doppler Effect
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the change in frequency produced by a moving source with respect to an observer
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Doppler Effect Formula
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fo = fs(v±vo / v±vs)
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vo is positive if the observer moves towards the source
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vs is positive if the source moves away from the observer
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Mechanical Wave
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a wave that requires a medium to translate in
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Electromagnetic Wave
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a wave that does not require a medium
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Amplitude
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the maximum displacement from the equilibrium position
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Periodic Time
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the time needed to complete one full cycle
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Frequency
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the number of cycles completed in one second
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Frequency Formula
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f = 1/T
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Wavelength (λ)
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The distance between two crests or troughs
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Wavelength Formula
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λ = v / f (v is the wave speed )
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The energy carried by a wave is directly proportional to the amplitude squared
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standing waves
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a combination of two waves moving in opposite directions, while having the same amplitude and frequency
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Nodes
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positions on a standing wave where the wave stays in a fixed position due to the destructive interference
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Antinodes
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positions on a standing wave with the highest amplitude
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the number of nodes are always greater than the number of antinodes
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Sound wave
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a longitudinal wave composed of compressions and rarefactions, and whose speed is directly proportional to temperature
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Loudness
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depends on amplitude
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Pitch
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depends on frequency
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Sound Intensity
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the relative sound intensity compared to a specific standard intensity expressed in decibels
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humans can hear noises between 20 Hz and 20,000 Hz
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Formula for two open ends (antinodes are greater)
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λ = 2L / n (n is the harmonic level)
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Formula for a closed column (nodes = antinodes)
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λ = 4L / n (n is the harmonic level)
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Cheatography n. The art of mapping complex subjects into clear, instantly navigable reference guides.
