1. MESA Mouse Trap Powered Cars

3. Basic Competition Rules
Greatest distance travelled without leaving 6-foot wide track
Zero alteration of mousetrap
do not take the spring apart
do not drill holes in or paint the trap
except screw attachment holes
trap lock must be working and sprung with a pencil or similar object

4. Basic Car Design

5. Advanced Car Design

6. Physics of Mousetrap Car
Friction forces
Drag
Acceleration
Torque
Momentum

7. Friction Rubbing forces on moving parts
Effect: slows car and prevents maximum distance
Caused by:
excess wheel to road contact
poor wheel alignment
various parts rubbing when in motion

8. Wheel to road contact
Skinny wheels incur less friction than wide wheels
“total surface area” of all wheels

9. Skinny Wheels
Skinny Wheels work best

10. Poor Wheel Alignment
Axles should be aligned perpendicular to car; if not,
Cars veers to right of left
Excess friction between front and back axles

11. Moving parts rubbing Axles rubbing on car body
Axles rubbing on mounting screws or holes
Lever arm against body
String against body or axle
Wheels against body

12. Drag Anything that slows or stops the car Such as: Friction
Parts hanging off car
Wide lever arm or wheels

13. Acceleration Getting the car moving with trap
Strongest possible residual strength in mouse trap
Optimum lever-arm to car length ratio (also consider trap position)
Too long or short of lever arm reduces potential acceleration
Friction reduces acceleration

14. Torque Getting power to the wheels: ability to get car moving
Too much torque = less distance (wheel spin)
Too little torque = car will not move
Torque altered by changing power arm angle to axle
Firm string to axle attachment

15. Momentum Keeping the car moving after acceleration phase
less friction = greater distance
the heavier the car, the greater the momentum

16. Long vs Short Car Long Cars: less torque less speed less momentum
much longer acceleration period
Short Cars:
more torque
greater speed
more momentum
shorter acceleration period

17. Long Car

18. Short Car

19. Maximizing distance longest power arc (arm length) ideal torque
(mousetrap position)
largest wheel diameter (greatest distance per wheel revolution)
smallest axle diameter (most revolutions per inch of string)

20. Long Arm
2009

21. Large Wheel Diameter

22. Large Diameter wheels
Small Diameter Axles

23. Comes Down to Car with trap not modified least amount of friction
maximizes design acceleration capability
finds ideal torque for design
most possible momentum
stays on the track

24. Summary: Building Tips
Large drive wheels
Small drive axle
Do not tie string to axle
Axles perpendicular to car
Correct mouse trap relation to car length

25. Connecting arm to trap

26. Tip: Don’t tie string to axle

27. For More Info….

30. 2002

40. Attaching axle to car

41. drrusshill@gmail.com The End