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Section 6.6. Simple 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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Section 6.6 Simple 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.
Section 6.6 • simple harmonic motion – repetitious motion that would continue without stopping if there were no outside forces on the object
Section 6.6 • Imagine attaching a pencil to a guitar string, setting the string into motion while sliding a sheet of paper to the right underneath the string and pencil. • http://www.physics.uoguelph.ca/tutorials/shm/Q.shm.html
Section 6.6 • 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. • http://www.nhn.ou.edu/~walkup/demonstrations/WebAssignments/HarmonicMotion001.htm
Section 6.6 • 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. • The motion of objects with simple harmonic motion is represented by sine and cosine functions.
Section 6.6 • 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.
Section 6.6 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
Section 6.6 – Example 1 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.
Section 6.6 – Example 1 Sketch a diagram:
Section 6.6 – Example 1 Sketch a graph to represent the motion:
Section 6.6 – Example 1 Write a sine or cosine equation: Answer the question:
Section 6.6 – Example 2 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?
Section 6.6 – Example 2 Sketch a diagram:
Section 6.6 – Example 2 Sketch a graph to represent the motion:
Section 6.6 – Example 2 Write a sine or cosine equation: Answer the question: