Waves and Vibrations Vibration: The repeated back and forth motion about an equilibrium position.

Vibration of a Pendulum A pendulum is an object that swings back and forth from a starting point called an equilibrium position. Period: the time it takes for a pendulum to swing completely back and forth -The period for any pendulum depends on the length of the pendulum and the pull of gravity

Waves Simple Harmonic Motion: a back and forth motion, called an oscillatory motion. Sine Curve: a pictorial representation of a wave

Parts of a Wave Crest: the highest point on a wave Trough: the lowest point on a wave Amplitude: the distance from the midpoint of a wave to the crest (or trough) Wavelength: the distance from the top of one crest to the top if the next crest

What Happens if I Increase the Amplitude of a Wave? -If you increase the amplitude of a sound wave then that sound gets louder - this is what an amp will do in your car increase the amplitude of the sound waves making the music louder -For AM radio stations AM stands for amplitude modulation. Different stations send out signals of different amplitudes

What will happen if I change the wavelength of a wave? - The smaller a wavelength gets the greater energy that wave has

Frequency Frequency – the number of vibrations an object makes in a unit of time Frequency = 1 / period Hertz – a measurement of frequency - one cycle per second

What will happen if you increase the frequency of a wave? - As you increase the frequency the pitch goes up For FM radio stations FM stands for frequency modulation sends out their signal MHz or 102,500,000 times per second

Wave Motion The energy transferred by a wave from a vibrating source to a receiver is carried by a disturbance in the medium.

Wave Speed The speed of a wave depends on the medium that the wave is moving through. v = λ ƒ V means velocity (measured in m/s) λ means wavelength (measured in meters) ƒ means frequency (measured in cycles/second or Hz)

Transverse Waves Transverse Waves: A wave with vibrations at right angles compared to the direction the wave is traveling

Longitudinal Waves Longitudinal Waves: A wave with particles vibrating parallel to (or along with) the direction the wave is traveling.

Wave Interference When two waves cross over each other the interfere or affect the shape of one another. Interference patterns happen when wave from different sources arrive at the same point at the same time

Types of Wave Interference Constructive Interference: when the crest of one wave over laps the crest of another wave and the two crest heights are added together Destructive Interference: when the crest of one wave overlaps the trough of another wave those waves try to cancel each other out.

How Two Different Waves Line up Out of Phase: when the crests of one wave overlaps the troughs of another wave to produce regions of zero amplitude. - this creates destructive interference In Phase: When the crests of one wave overlaps the crests of another wave and the troughs overlap as well - this creates constructive interference

Standing Waves Standing Wave: A wave that appears to stay in one place. xt=1&index=13 Node: the stationary points on a standing wave Antinode: the positions on a standing wave with the largest amplitudes

The Doppler Effect When a ambulance or police car is coming toward you then passes you with the siren going does it sound different before it passes you then after it passes you? The Doppler Effect: As a wave source approaches, an observer encounters waves with a higher frequency. As the wave source move away, an observer encounters waves with a lower frequency.

Red Shift Vs Blue Shift As a wave coming from a moving object approaches an observer the wave are pushed closer together increasing the waves frequency or number of times waves reach you. This is red shift. When the moving object passes the observes the waves are farther apart lowering the frequency or the number of times waves reach you. This is blue shift

Bow Waves Bow Waves: this is a type of wave made when the source of the wave moves faster than the wave it produces.

Shock Waves Shock Wave: a three-dimensional wave that consists of overlapping spheres that form a cone - this happens when a object is moving faster than the speed of sound