This video references Newton's Second Law of Motion. This pertains to the acceleration of objects. The marbles shown in the video are dropped onto solid ramps (action) that are at a downward angle. Gravity acts on the marbles (reaction) and they continue to move down until they are dropped in a bowl (action). They continue to move around due to the momentum acquired from moving down the ramps (reaction). The bowl is also sloped, which causes them to move towards the center (reaction). One of the marbles bumps into another (action) causing the other to move forward (reaction). The bowl liquifies (action), which causes the marbles to move down the slope that is created (reaction).
