3. Testing and Modification

3.1 Trial Test and Design Modification

Run Number	Run 1	Rerun 1	Rerun 2
Total time of Run	8s	7s	4s
Total distance of Run	8m	8.2m	1m
Time for lever to fully release	1.2s	1.0s	1.3s
Distance car travels while lever is releasing	0.3m	0.4m	0.3m
Observations – did car travel smoothly, straight, always forward, etc?	veered sharply to the right off the track.	turned to the right more gently than the first round.	turned towards the right.
Did lever / string operate smoothly?	Yes	Yes	No. The string got tangled in the axle before it was released fully.
Filename of video recorded is:	None	None	None
Area for improvement (1 only)	Change the length of the string to be shorter
Possible reason (1 only)		This is because it tended to be tangled up in the axle.
Modification made (1 only)			Reduced the string length.

MODIFICATION (New Google-sketchup)

3.2 Test Data
1. All relevant measurements of car (after modification)

Mass of car: 262.5 g
Mass of each wheel (or one of they are all the same): 1.6g
Wheel diameter: 12cm
Axle diameter: 0.4cm
Length of string (power stroke): 17cm
Approx. number of wraps of string: 9 wraps
Length of lever extension: 0cm (none)
Overall length: 40 cm
Overall width: 19.5 cm
Overall height: 9.5 cm

2. Data tables showing the results of all 3 trials. 

Run Number	1	2	3
Total time of Run	9.2s	9.1s	8.9s
Total distance of Run	8m	8m	8m
Time for lever to fully release	0.9s	1.1s	1.1s
Distance car travels while lever is releasing	0.3m	0.3m	0.3m
Observations – did car travel smoothly, straight, always forward, etc?	turned slightly to the right	turned slightly to the right	turned to the right and headed for the camera
Did lever / string operate smoothly?	yes	yes	yes
Filename of video recorded is:	none	none	CIMG0253

3.3 Video Clips
At least 3 best videos are recorded and upload into Youtube. The 3 links are pasted here and in the Blog.

http://www.youtube.com/watch?v=zBYGtAy3Uyc&feature=youtu.be