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

[SonicBoomxxx]

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?

 

[russ_watters]

What does their mass have to do with anything?

 

[dean barry]

With an infinitely long connecting rod, you would have comparable acceleration and velocity values for the piston and crank pin.

 

[Khashishi]

A piston can have any motion you want. Are you talking about some very specific application of a piston?

 

[Raptor]

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.