Simple Harmonic Motion!? Hi All, New to the forum, sorry if this is a thread that has been discussed before, however I've had a quick look and have been killing myself for days over this. Approached my college tutor today and he couldnt explain it!? I'm almost sure that it is something easy and simple, but as it stands at the moment, I cant see the light! Ok, the question... I understand that SHM can be thought of as circular motion, I have read through the derivations, beginning with the centripetal acceleration equation a=ω^2r (r as radius)....and ending with with the SHM equation of motion a=-ω^2x My problem is that my book says the ω in the SHM equation is "a positive constant with units of s^-2", which I understand is Hertz^2 right? At what point and how does the ω change from rad/s to s^-1? (I know there is a relation between the two, however as far as I could see on the internet, a hertz is a cycle per second, but that means per cycle there is 2∏ rad/s? So they arent equivalent...) Also, I found the equation ω=√k/m is the equation to find angular frequency? Whats the relation between angular frequency, angular velocity, hertz considering they are all s^-1? The other problem relating to this I have is the fact that when looking for the period of motion of a circle the equation is T=2∏/ω......where ω is the angular velocity. and...the period of motion of an oscillation is T=2∏/ω but here ω is in hertz? Very sorry if this is confusing or that its a ridiculous and stupid question, I'm sure you've all had that Math/Physics block at some point where you just cant see it at first.... Please explain all you can, bare in mind I'm fairly new to Physics, so dont hit me with hugely complicated stuff if it can be helped. Much appreciated if anyone can help! Thanks.