# What is the difference between reciprocating and oscillating motion? How is reciprocating motion different from simple harmonic motion?

I wanted a good explanation for the difference between reciprocation and sinusoidal motion (For e.g. SHM). This question has been posted here due to many ambiguous and unclear explanations round the Web.

For a motion to be called simple harmonic, the force should be proportional and opposite to the displacement: $$F = -kx$$. Reciprocating motion is just a back-and-forth motion and per se, does not have to follow said law.
• Uniform circular motion and simple harmonic motion are very closely related: the projection of a particle exhibiting $\textbf{uniform}$ circular motion performs a simple harmonic motion. byjus.com/physics/… That is what is said about the motion of the rotating part. The part of the connecting rod connected to the piston, however, does not exhibit a simple harmonic motion, because the angle of the rod changes continuously. – thunderbolt Jun 16 at 11:00