Demos: 1C-04 High Road, Low Road Race
Two wooden tracks have identical starting and ending points. One is straight, whereas the other drops downward, then goes straight and then goes back up. Both balls are started at the same time and with the same initial speed. Although the track with the “dip” is considerably longer, the ball on that track arrives first, showing that the average speed of this ball is greater than that on the flat track.
Directions: Place the two balls at the starting point. A mechanical starting device insures that the balls are launched simultaneously and with the same initial speed.
Suggestions for Presentation: Present the students with the confusing array of variables: one track longer than the other, one ball speeding up then slowing down, etc. Ask if its possible to predict qualitatively which ball should reach the other end first. After performing the demo, focus the discussion on the average speed of each ball.