 So now we have a pendulum prop and this is the one that my students are filling out a worksheet for. So let's work through this one step at a time. I've got a 0.75 meter long pendulum that has a 4 kilogram mass attached to it. And the pendulum oscillates with a small amplitude. Now some of this information is just setting us up to know that we do have a simple pendulum that follows the rules for the equations we're using. We've got a couple of knowns here, the length of the pendulum and the mass of the pendulum. We also have the value for gravity because we're going to assume this is on earth. Now for the first part of the problem I have to determine the angular frequency. So my first question for you is what's the symbol for angular frequency? And what's the equation that goes with that? For a simple pendulum, omega is the angular frequency symbol and it's the square root of g over l. If I have a spring oscillator or a pendulum that's not a simple pendulum I might have a slightly different equation here. But we know these values so we can go ahead and plug them in. I'm going to use 9.8 for my gravity and my length is my 0.75 meters. When I do this calculation I get a value of 3.61 radians per second. I do want to go over here just real quick how I got those units. And again you should be plugging these things into your calculator to make sure you come up with the same answer so you know you understand the problem. So here on these units we have meters per second squared over meters inside the square root. When the meters cancel that leaves me with 1 over second squared or at least it looks like it just leaves me with a 1 over second squared. But remember there can be radians as sort of a place holder. And when I take the square root here the radians is still there as the place holder and my second squared becomes just a single second. So this is the kind of unit I have for angular frequency. I know the units are a little strange on these but just kind of follow through as best you can.