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Unformatted text preview: PHY122 Labs ( © P. Bennett, JCHS) -1- 09/18/06 PHY 122 LAB: Springs and oscillators Introduction In this lab we will measure the static behavior (stretch vs. force) of simple springs, practice linear fits to find the static spring constant, then make an oscillator and test the relationship between frequency and mass to get the dynamic spring constant. Springs, like those in your car's suspension, or between atoms in solids, are important because they produce simple harmonic oscillator motion (SHM), which occurs throughout all of physics and electrical and mechanical engineering. Text Reference: Y&F 6.3, 13.2. Theory - Hooke's law and Simple Harmonic Motion. An ideal spring is massless and linear. That is, it obeys Hooke’s law: F(X)=-k s (X-X ) Eq. 1 where F is the force exerted by the spring (it opposes the stretch) and (X-X ) is the stretch, measured from the resting position (zero force at X ), and k s is the static spring constant. In this lab, the force arises from calibrated weights hung vertically. Hence, we have F = mg. F is in Newtons for “m” in kg and g = 9.80 m/sec 2 . (Real springs have mass and are a little non-linear. In this case, it is useful to define a local or differential spring constant in terms of the derivative...
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This note was uploaded on 05/11/2008 for the course PHY 122 taught by Professor Fan during the Spring '08 term at ASU.
- Spring '08