You could also do this with a trolley attached to a mass that is hanging off an edge. Then you let go of the mass and it falls to the ground, dragging the trolley with it. Maybe at the edge of the table you could have a barrier.
On a slight tangent, which may be helpful information to others, however I don't think you should put this in your assignment: You could attach some sort of crumpling block (like foam or a sponge) on the barrier so that the trolley hits it and investigate the effects of increasing/decreasing impulse applied on crumple zones.