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Harmonic Motion. Describe the motion of a rider on a ferris wheel relative to the ground. Describe the motion of a buoy in an ocean relative to the ocean floor:. Describe the motion of a vibrating horizontal guitar string. Describe the motion of a piston in a cylinder.
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Describe the motion of a rider on a ferris wheel relative to the ground.
Describe the motion of a buoy in an ocean relative to the ocean floor:
Describe the motion of a vibrating horizontal guitar string.
Harmonic Motion • simple harmonic motion – repetitious motion that would continue without stopping if there were no outside forces on the object
Harmonic Motion • “if there were no outside forces on the object”
Harmonic Motion • “if there were no outside forces on the object” • swinging pendulum
Harmonic Motion • “if there were no outside forces on the object” • swinging pendulum - gravity
Harmonic Motion • “if there were no outside forces on the object” • swinging pendulum - gravity • mass in a spring-mass system
Harmonic Motion • “if there were no outside forces on the object” • swinging pendulum - gravity • mass in a spring-mass system – gravity, friction
Harmonic Motion • “if there were no outside forces on the object” • swinging pendulum - gravity • mass in a spring-mass system – gravity, friction • vibrating guitar string
Harmonic Motion • “if there were no outside forces on the object” • swinging pendulum - gravity • mass in a spring-mass system – gravity, friction • vibrating guitar string - tension
Harmonic Motion • “if there were no outside forces on the object” • swinging pendulum - gravity • mass in a spring-mass system – gravity, friction • vibrating guitar string - tension • floating buoy
Harmonic Motion • “if there were no outside forces on the object” • swinging pendulum - gravity • mass in a spring-mass system – gravity, friction • vibrating guitar string - tension • floating buoy • ferris wheel
Harmonic Motion • “if there were no outside forces on the object” • swinging pendulum - gravity • mass in a spring-mass system – gravity, friction • vibrating guitar string - tension • floating buoy • ferris wheel – mechanical/human
Harmonic Motion • “if there were no outside forces on the object” • swinging pendulum - gravity • mass in a spring-mass system – gravity, friction • vibrating guitar string - tension • floating buoy • ferris wheel – mechanical/human • piston in a cylinder
Harmonic Motion • “if there were no outside forces on the object” • swinging pendulum - gravity • mass in a spring-mass system – gravity, friction • vibrating guitar string - tension • floating buoy • ferris wheel – mechanical/human • piston in a cylinder – friction/ human
Harmonic Motion • We know that the motion of objects with simple harmonic motion can be represented by a sine or cosine function. • Here’s why: If you were to trace out the object’s motion over time (or some other x-coordinate quantity), the result would be a sine or cosine function.
Harmonic Motion • Imagine attaching a pencil to a guitar string, setting the string into vibration while sliding a sheet of paper to the right underneath the string and pencil. • Or imagine attaching a pencil to the outside edge of a circular object and sliding a sheet of paper to the right while the circle was turning counterclockwise.
Harmonic Motion • If we know some information about the object’s motion, typically the position at some time and its frequency, then we can write an equation that will model its motion.
Harmonic Motion • Problem - solving strategy: • make and label a diagram • make and label a sine or cosine function graph • write an equation to represent the graph • answer the question
Harmonic Motion A buoy floats in a harbor at a location where the water depth is 26 ft. As waves pass the buoy it rises and falls. The buoy moves a total of 8 ft from its lowest to its highest point every 12 seconds. Assume the buoy is at its low point at t = 0. Find the height of the buoy after 15 seconds.
Harmonic Motion Sketch a diagram:
Harmonic Motion Sketch a graph to represent the motion:
Harmonic Motion Write a sine or cosine equation: Answer the question:
Harmonic Motion A mass in a spring-mass system is at rest 5 ft from a 10 ft ceiling. The mass is given a push up at time, t = 0. The mass is 2 ft from the ceiling at its highest point and it takes 4 seconds to complete a cycle and return to its starting position. What is the mass’ height 10 seconds after being set into motion?
Harmonic Motion Sketch a diagram:
Harmonic Motion Sketch a graph to represent the motion:
Harmonic Motion Write a sine or cosine equation: Answer the question: