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How Fast is that? Ice skaters 1 Video By Matt Vonk 1. Watch the video all the way through. Displacement: Displacement is the difference between the ending position and the starting position of an object. 2. What is the displacement of the people (and dog) as they move from the line on the right to the line on the left? 3. Displacement is different than distance, for example, watch the motion of the left glove of the third skater as it travels between the two lines. Notice that the glove moves back and forth in such a way that the total distance it travels is greater than the 5 m distance between the two lines. However, since displacement is just the difference between the final and initial positions of the object, the third skater's glove will have the same displacement as the first skater's boot or the dog’s nose. Average Velocity: Average Velocity = displacement / time. 4. Measure the displacement of the left boot of the skater in a blue jacket as the boot travels between the two lines. 5. Measure the number of frames the tip of the boot requires to travel between the two lines. 6. Convert frames to seconds. Here's an example: 18 frames x ( 1 second / 240 frames/s ) = 0.075 s
