The first runner because it is very clear that accelarition depends on the time and we know that the time in this case is pretty simple
Tension in the rod is responsible for balancing force due to gravity.
Answer:
Poke or kick the boxes. The sand box is the one that resists the most
Explanation:
The one that resists the most a change in motion (inertia) is the one with the greater mass—the one filled with sand. Since we cannot open the boxes or perform any weight measurement we can distinguish them by their inertia. Sand has greater mass and thus greater inertia