



 
Hi Kim, I assume your graph looks like the following:
I assume you mean that the period is 4 seconds. The formula for angular speed is ω=2 π/T where ω is angular speed and T is period length. The unit for angular speed is radians/second. If you want to find the speed in cm/second, that is actually linear speed. The angluar  linear speed relation is v=r*ω where v is linear velocity and r is radius. Since you are given a sine graph showing distance versus time, your amplitude shows what the radius is for your angular speed. Hope this helps, Janice  


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