Newton's First Law states that objects in motion stay in motion and objects at rest stay at rest unless acted upon by an unbalanced force. For Newton's first law I built a marble track. The unbalanced force in my video would be the box stopping the marble from rolling. The forces involved in this experiment would be gravity, which keeps the marble on the ground, centripetal force, which keeps the marble rolling in a circle, contact force between the box and the marble and finally friction which decreases the marble's speed, and eventually causes it to stop.
Photo used under Creative Commons from manoftaste.de