This experiment uses a disk that accelerates down a slope very slowly.  Thanks to Mark Schober for creating an example of this using electrical conduit as rails, a CD as a disk and a steel rod as an axle.  Here simple meter sticks are used with a paper disk.  As the disk picks up speed very slowly, you can use a single sensor to make time measurements, pointing it upward when moving it to a new location, and pointing it in the path of the disk to capture the time.

 

Thanks to Brendan Walsh for creating this demo.