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**Periodic/Simple harmonic motion is back-and-forth motion.**Springs are one example http://www.physicsclassroom.com/class/waves/Lesson-0/Properties-of-Periodic-Motion Spring simulation**Pendulums are another example of simple harmonic motion**Set up pendulum**When you hear the terms vibration or oscillation you should**think of periodic motion.**Measuring periodic motion**Amplitude - max displacement SI unit can be radians or meters Period (T) - time it takes for one complete cycle. SI unit is seconds**What is the period of the second hand on a clock?**What is the period of the minute hand on a clock? What is the period of the hour hand on a clock?**Frequency ( f ) - # of cycles per unit of time, how many**waves go by per time. f = 1/T SI units are Hertz (Hz) Hz = 1/s How is frequency related to radio stations?**A fly flaps its wings back and forth 150 times each second.**The period of the wing flapping is ____ sec.**Non-digital clocks (which are becoming rarer) have a second**hand that rotates around in a regular and repeating fashion. The frequency of rotation of a second hand on a clock is _______ Hz.**What is simple harmonic motion?**• Give 2 examples of simple harmonic motion. • The time it takes for one complete cycle is called __________. • If I know the frequency how do I calculate the period? • What are the SI units for frequency?**Day 3**Quiz 1**What is a wave?**A disturbance or vibration that transfers energy.**What travels as a wave?**Energy Light, sound, water, x-rays, radio waves**Mechanical waves - when energy moves through a medium in a**vibration. A medium is a collection of interacting molecules A wave transports energy not matter.**https://www.youtube.com/watch?v=RVyHkV3wIyk intro to waves**https://www.youtube.com/watch?v=RVyHkV3wIyk intro to waves**3 main types of mechanical waves:**http://scienceprimer.com/types-of-waves**Parts of a wave:**Wavelength ( λ ) - the distance between 2 troughs or crests. Speed/velocity (v) - is how fast the wave is moving. Amplitude (a) - maximum displacement**Transverse waves**- Cause the medium to vibrate perpendicular to wave motion.**Longitudinal waves**- Cause the medium to vibrate parallel to wave motion. - Example: Sound**Surface waves**- Travel on the surface of a medium (between 2 mediums) - moves in circles - example - ocean waves**Energy and Amplitude- High energy = high amplitude- Low**energy = Low amplitude**http://www.physicsclassroom.com/Physics-Interactives/Waves-and-Sound/Simple-Wave-Simulator/Simple-Wave-Simulator-Interactive**http://www.physicsclassroom.com/Physics-Interactives/Waves-and-Sound/Simple-Wave-Simulator/Simple-Wave-Simulator-Interactive**The piano string tuned to middle C vibrates with a frequency**of 264 Hz. Assuming the speed of sound is 343 m/s, find the wavelength of the sound waves being produced.**The piano string tuned to middle C vibrates with a frequency**of 264 Hz. Assuming the speed of sound is 343 m/s, find the wavelength of the sound waves being produced.**The smallest insect that a bat can detect are the size of 1**wavelength of the sound the bat makes. What is the minimum frequency of sound waves required for the bat to detect an insect that is 0.57 cm long? Assume the speed of sound is 340 m/s.**The smallest insect that a bat can detect are the size of 1**wavelength of the sound the bat makes. What is the minimum frequency of sound waves required for the bat to detect an insect that is 0.57 cm long? Assume the speed of sound is 340 m/s.**As waves pass by a duck floating on a lake, the duck bobs up**and down but remains in essentially one place. Why?**As waves pass by a duck floating on a lake, the duck bobs up**and down but remains in essentially one place. Why? The medium does not actually travel with the wave.**Speed and Medium**• The wave speed in a mechanical wave is determined by the medium the wave is traveling through. • The speed is independent of frequency or amplitude.**What are the 3 types of mechanical waves?**What kind of wave is sound? Wavelength? Crest? Trough?**Behavior of waves**• Reflection • Refraction • Diffraction • Interference • The Doppler effect**Refraction - a change in the direction and speed of waves**as they pass from one medium to another.**Diffraction - a change in direction of waves as they pass**through an opening or around a barrier in their path.