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Unformatted text preview: Phy 7C Review of Oscillations and the SHM Model from Phy 7B Unit 7 Page 1 Oscillations and the Simple Harmonic Motion (SHM) Model (Review of material treated in Unit 7 of Physics 7B) Introduction Many physical phenomena exhibit “vibrations.” The everyday use of the word “vibrate” to mean that something moves back and forth, usually in a regular way, is very close to what is meant by “vibration” or “oscillation” in physics. When we examine objects that are oscillating, we notice several features. The motion repeats in a cyclic manner. As the object moves toward one extreme, a net force acts on the object, causing it to stop and move towards the opposite extreme. In order to make these ideas more precise we introduce a model of a very common kind of oscillation, called simple harmonic motion. Some oscillations occur with abrupt changes in an object’s motion. An example is a vertically bouncing ping-pong ball. Going down, the ball changes direction very rapidly when it hits the table. Going up, it gradually comes to a stop and then gradually begins moving down. In contrast, a swinging pendulum changes its direction at both ends of its swing in a very smooth way. This latter, very smooth oscillatory motion is called simple harmonic motion. Because this motion is so common, it is useful to formulate a simple harmonic motion (SHM) model. This model will become the starting point of a wave model taken up in Unit 8. The essential elements of the SHM model (as well as all other models) include constructs (the ideas that form the building blocks of the model), the relationships between the constructs, and the representations that allow us to readily use the model to develop explanations of various phenomena, make precise predictions regarding oscillatory motion, and, in general, to use the model...
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This note was uploaded on 08/21/2011 for the course PHYS 7c taught by Professor Coleman during the Summer '09 term at UC Davis.
- Summer '09
- Simple Harmonic Motion