Simple Harmonic Motion

You would know how sonething is a harmonic motion if the object moves up or down/ side to side and changes from Kinetic energy to Potential energy without adding anymore force. One example of harmonic motion that I've seen today have been the lucky cat. This cat is a harmonic motion because its paw moves up and down at a constant rate without any force been added. Another example of a harmonic motion that I've seen today  was the washer in the string in today's lab. This is harmonic because it moves from side to side changing from kinetic energy to potential energy constantly. Another harmonic motion object I saw today was a slinky. This slinky is a harmonic motion object because once you let some of it go, and hold it in the air, the spring moves up and down changing from kinetic to potential energy.