Your Lego Racer as a Measuring Device

Activity Objectives: The point of this activity is to create a Lego racing car that will travel a consistent distance no matter how many times the car is raced.

Activity Procedure: Build a Lego racing car. Test five different variations of the car over five test runs to try to determine the most reliable configuration. Once the best and most consistent model has been discovered use that model over a series of 20 runs

The surface I ran the test on was a polished hard wood floor starting my kitchen and ending in my living room. The total floor was about 30 ft from end to end. I then put a long tape measure on the floor against which I would measure how far the racer travelled. The racing car was then powered by winding the crank 5 times. I held the racer in the back so as not to affect its configuration. The racer was then placed on the floor and allowed to run. The measurements where taken from the back of the racer at the start to the front of the racer when it finally stopped. The distance travelled was then recorded on the spreadsheet provided. The need to hold the racer in the back was discovered after holding the racer in different positions all of which seemed to change the configuration.

Racer configuration change

1 - Just built no changes

2 - Moved back wheels out a bit

3 - Moved front wheels to ends of axle, back wheels up tight then moved out 1mm

4 - Wheels 1mm from side of racer front and rear

5 - Front wheels 1mm out, rear whels out as far as possoble

Final Confiruration: Front wheels out 2mm, rear wheels as far out as possible so that the rear wheels would not disengage from the gears powering them.

Data and Analysis:

The final racer configuration was used to run a series of 20 tests. The racer consistently went about 26 feet. The minimum distance travelled was 23ft 9 inches and the maximum distance travellered was 23 ft 9 inches. The average distance travelled was 26.2 feet with a standard deviation of 7.61

Discussion and Conclusion:

Model Configuration Issues: The changes being made to the model where all made to try and optimise the distance the racer would travel. To get the model to travel the furthest I moved the rear wheels almost to then end on the axle it was on. I moved the front wheels out about 1mm on either side of the racer. What is not really discussed here is that racer went down the course in an arc. Since the width of the track I had was limited the racer sometimes bumped into the side of the track. These occassional collisions affected how far racer travelled. Having identified the outside influences on the results I think the