Note the Physics

• What happens to the ball as it moves on a level track?
• The spacing between adjacent images tells us about the ball's speed -- larger spacing means higher speed since a faster ball can travel further in the same time span.
• If the spacing remains constant, the ball moves at constant speed.
• Changes in the spacing indicate that the ball is speeding up or slowing down (depending on whether the spacing increases or decreases).
• Look at the image spacing at the beginning of the motion. Is the ball moving initially, or has it started from rest?