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Simple Harmonic Motion. Periodic motion that has a restoring force that is proportional to its displacement Back and forth motion (repetitive motion) Springs, Pendulums, Waves. Types of SHM. Springs Hooke’s Law – F = - kx PE = ½kx 2 Period (T) = 2 m/k. Pendulums Period (T) = 2 L/g.
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Simple Harmonic Motion • Periodic motion that has a restoring force that is proportional to its displacement • Back and forth motion (repetitive motion) • Springs, Pendulums, Waves
Types of SHM Springs • Hooke’s Law – F = -kx • PE = ½kx2 • Period (T) = 2m/k Pendulums • Period (T) = 2L/g
Waves • Carry energy • Pulse – a single disturbance of a wave • Transverse vs. Longitudinal • Mechanical vs. Electromagnetic
Types Transverse vs. Longitudinal • T – energy and movement are perpendicular • Example – the “wave” done by sports fans during an event • L– energy and movement are parallel • Example – a mosh pit Mechanical vs. Electromagnetic • M – requires a medium(source) in order to travel • Example - sound • E – does NOT require a medium to travel • Example - light
Properties • Wavelength – distance from one area to the next corresponding area on a wave • Frequency – the number of waves that pass a point in a certain amount of time • Amplitude – the amount of energy carried by the wave (E is proportional to A2)
Properties • Speed – how fast a wave moves = its determined by the MEDIUMin which the wave travels • Speed = distance = wavelength * frequency time • When a wave enters a new medium, the wavelength changes while the frequency stays the same
SuperpositionThe combining of two or more waves Constructive Interference • All the waves are going in the same direction and are in sync with one another • Waves add together Destructive Interference • All the waves are NOT in the same direction and are NOT in sync with one another • Waves cancel out
Reflection Free Boundary • End is ABLE to move • Reflected wave is the same as incident wave Fixed Boundary • End is UNABLE to move • Reflected wave is the inverse of incident wave
Refraction • The bending of waves as they move from one medium to another
Diffraction The bending of waves through an opening or around a barrier Think of water waves
Sound Waves • Speed of sound in air is 343 m/s • Require a medium = mechanical • Longitudinal • Echo = reflection of sound • Pitch = how high or low a sound is = frequency • Loudness = depends on the amplitude
Light Waves • Speed of light in vacuum = 3.0 X 108 m/s • Does NOT require a medium = electromagnetic • Transverse • Mirrors = reflection of light • Lenses = refraction of light
Types of Reflection Specular Diffuse
Law of Reflection Angle of incidence = angle of reflection
Mirrors Flat, Plane Mirrors Bathroom mirrors Concave Used for magnification Convex Makes images smaller Used in side mirrors of cars
Lenses Concave • Used the make images smaller Convex • Used in camera lenses, microscopes, magnifying lenses