To find linear footage you simply need to measure the length in feet thats it. RPM is the rotation rate rpms of the pulley. If you need to calculate average speed and you know the total distance covered and the total time it took to cover that distance divide the distance into the total time.
The term linear means a shape or movement in a straight line.
The Angular to Linear Velocity formular is. Radius in meter RPM. To find linear footage you simply need to measure the length in feet thats it. All you need to do is measure their revolutions per minute n and the carousel radius R.