Here's a simple problem:
How long will it take the block to slide that distance?
Write down your work on a piece of paper. Hand the paper to an instructor.
Then, and only then, may you perform the experiment. Calculate the actual acceleration of the block down the track.
How does the actual acceleration of the block compare to the theoretical value?
If you have time ... Does the condition of the track affect your result? Clean your track gently with paper towels, then repeat the experiment. Do you find the same acceleration? What sort of uncertainty should you attach to your measured acceleration?