Harmonic motion is when an object pretty much goes back and forth, right? Also, what does the word 'strobe' mean? I once heard a member here say that if our eyes worked like a camera and took a picture 60 times a second that a light that flashed 61 times per second would appear to strobe at one flash per second. Why is this? What if the light flashed at 38 times per second? Also, what does it mean for one thing to be 'in harmony' with another object? What does it mean to be 'in phase'? This is just an area I feel I'm lacking in knowledge so I'm asking for help.