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# Sample Design Record

### Materials Needed:

 4 pop tops 4 index cards 2 skewers 2 straws 2 straws tape hot glue

### Design Process:

 Design Decision Rationale 4 Wheels More Stable 8” x 2.5” Longer body should go straighter Weight holder above rear axle Ease transition between ramp and floor by allowing front to pivot on back axle Encase holder in wedge shape Better aerodynamics, use back for motion detector ¼” rail assembly More rigid, durable construction Overlap center joint by 1” Stronger joint

### Design / Performance Evaluation:

 Design Problem Resolution Loss of masses on transition from ramp to floor Add support under mass holder Bending of frame during transition from ramp to floor Add rail along length of car, additional rail across middle for more support Car turns to right Adjust wheel/axle to make car go straight

### Performance Data (fabricated):

 Trial # Variables Graph Slope/Velocity Conclusion 1 Mass:10gAngle:45 .5 m/s Test larger angle 2 Mass:10gAngle:60 .2 m/s Test smaller angle 3 Mass:10gAngle:55 .3 m/s Test smaller angle 4 Mass:10gAngle:35 .6 m/s Test slightly larger angle 5 Mass:10gAngle:40 .8 m/s Test slightly smaller angle 6 Mass:10gAngle:37 1.0 m/s Optimum angle =37 Test mass 7 Mass:20gAngle:37 1.5 m/s Test larger mass 8 Mass:30gAngle:37 1.7 m/s Test slightly smaller mass 9 Mass:25gAngle:37 1.9 m/s Test slightly smaller mass 10 Mass:22gAngle:37 2 m/s Optimum mass = 22g

### Conclusion:

Using 22g and an angle of 37 degrees, the car should reach an average velocity of 2 m\s during its run.

In addtion to the above, students should also have:

• General procedure used to collect the data.
• at least three graphs drawn on graph paper including the "best fit" line. The students should also include the mathematical steps required to find the slope of the line.

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