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Why is the motion of a piston considered to be simple harmonic motion?

  1. Nov 6, 2014 #1
    I know this is simple, but I don't fully understand why the motion of a piston is considered to be simple harmonic? Wouldn't the piston and connecting rod have mass?
  2. jcsd
  3. Nov 6, 2014 #2


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    Staff: Mentor

    What does their mass have to do with anything?
  4. Nov 7, 2014 #3
    With an infinitely long connecting rod, you would have comparable acceleration and velocity values for the piston and crank pin.
  5. Nov 7, 2014 #4


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    Science Advisor

    A piston can have any motion you want. Are you talking about some very specific application of a piston?
  6. Nov 7, 2014 #5
    Simple harmonic motion is for small vibrations in an isolated system(free from damping forces). If you have a pendulum of mass 20g it can also undergo shm. Mass just affects it's time period. A piston can also undergo shm.
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