“SECME: 21st Century
Pioneers – Dreaming Today
To Discover Tomorrow”
Basic Instructions For the
Mousetrap Car Competition
Team entry: 3 students required
Design
Mousetrap car construction and run
Communication
Technical report writing
Design drawings
Team interview with Judges
Mousetrap Event Final Scoring
Total of the following scores
Mousetrap car performance (100 pts max)
Design drawing (50 pts max)
Technical report (50 pts max)
Team interview (50 pts max)
Total Max – 250 pts
Design drawing
Title card (4” X 6”)
„
„
„
„
„
Team name
School name and address
Team members names, addresses and grade levels
School coordinator’s name
Date of Competition
Paper size (18” X 24”), 1” margins,16” X 22” actual drawing
Must show scale and units (use 1:1 and inches if possible)
Label all parts
Three views (front, side and rear)
Dimensions
Accuracy
Neatness (pencil and fully erase)
REAR VIEW
FRONT VIEW
SIDE VIEW
Title: SECME Mousetrap Car
Drawn by: Lavonis Dubose
Date: 1/25/2003
Scale: Full
1” = 1”
Technical Report Writing
Describe the design, construction and operation
Computer printed, 12 pt. Type, double-spaced
White, 8-1/2” X 11” paper, 1” margins
Maximum of 5 pages
Graded on
Outline
Organization
Precision
Sentence formation
Mechanics
Technical Report Organization
Cover page (required to contain)
Title
Name, addresses and grade of team members
Team’s school name and address
School system name
School Coordinator’s name
Date
Abstract (1/2 page summary)
Table of contents (1 page)
Introduction
Design
Construction procedure
Operation of the mousetrap car
Conclusions / Recommendations
Acknowledgements
Appendix (sketches, tables, charts etc.)
5 page maximum
Team Interview
Requirements
„
All three members present
„
Each responds to questions
„
Work is students’ own
„
True team effort is evident
Team Interview
Evaluation Categories
„
Teamwork
„
Application of technical principles
„
Knowledge of design
„
Oral communication skills
Mousetrap Race Scoring
2
Weight of Mousetrap
_________________
Weight of Car
Goal: Minimize weight
Minimize length
Maximize distance
Distance
_______
Length
Basic Instructions For
Building A Mousetrap Car
This is a set of basic instructions and tips on how to
get started building a mousetrap car out of balsa
wood.
Many other materials and designs are possible
Adapt the instructions to your needs and imagination.
Materials
Mousetrap
Chassis: wood scraps, balsa wood, ice cream sticks, stiff wire
Axles: wooden dowels, metal tubes (copper or brass), axles
from old toys
Wheels: Metal lids, CDs, wheels from old toys, other diskshaped objects
Pull Cord: String, rubber bands or fishing line
Glue (strong enough to withstand force of mousetrap)
Tools: Pliers, screwdrivers, hammers, handsaws and drills
Use recycled materials whenever possible
Physics Concepts
Friction
Friction is the resistance of motion between two objects. Most friction
between the materials in your car reduce the amount of energy that is used
to move the car, so it would make sense that you want to reduce that
friction. However, you actually rely on the friction between your wheels and
the floor to help your car move.
Another, less thought of, friction involved in the performance of your car is
air resistance. Remember, air resistance acts against the motion of the car
and therefore should be reduced to increase performance.
Physics Concepts
Newton’s Laws
Newton’s first law is also known as the law of inertia. Inertia is an
object’s tendency to resist change. The more massive an object
is, the larger its inertia, and therefore the harder it is to change its
motion. Newton’s second law is most commonly known in its
equation form, F=ma. Both of these laws should show you that the
more massive your car, the more force that will be required to
move the car. Remember that, depending on the goal of the car,
you may want the car to have some inertia so it will keep moving
after the mouse trap has used all it energy. Keep these laws in
mind while constructing your car.
Physics Concepts
Rotational Inertia
Just like linear inertia deals with an object’s tendency to resist
change of its linear motion, rotational inertia is an object’s
tendency to change its rotational motion. The rotational inertia of
an object depends on its mass and the distribution of that mass.
Since the wheels of your car are the parts that are rotating, you
may want to decrease or increase their rotational inertia.
Physics Concepts
Energy
Energy can be defined as the ability to do work. Work is the
applying a force to an object, and actually moving that object. If
the object is not moved, no work is done. The goal of the project
relies on efficiently transferring the spring’s energy to the car’s
wheels. The concepts involved in the transfer of this energy rely
on an understanding of simple machines. The trap acts as a lever
to transfer the energy to the axle. The axle acts on the wheel as a
second transfer of the energy. Finally, the energy is used to push
the wheel against the floor, causing the car to move. Any friction
or resistance in the transfer of energy, leads to a decrease in the
efficiency of the machine and decreased performance. Keep the
use of simple machines in mind as you design the car, the
correct use of these machines will increase your performance.
Tips
Glue: Use a quick drying hobby glue. Pay attention to the drying time specified on the
bottle. Some glues will permanently set in as little as five seconds, giving you very little time
to position the pieces. If you glue your fingers together (or to the car!) use acetone or
nail polish remover to dissolve the glue. You may want to keep some extremely fast drying
glue at hand during race day!
Wheels: Old CDs make great wheels, but have very little traction. Stretch a wide rubber
band around each wheel; the rubber band can even be glued into place.
Pull Cord: Your pull cord needs to be strong enough to withstand the forces exerted by the
mousetrap spring. Fishing line, rubber bands (not legal in some competitions) or strong
string work well. Winding the pull cord in the wrong direction makes the car go backwards;
painting a small arrow on the axle as a reminder can help.
Alignment: A mousetrap car that always steers to one side will not be good for
competition. Place shims (small pieces of scrap wood) in between the bushings or bearings
of one or more of the wheels to align the wheels. It is very easy to do this with balsa wood.
Aerodynamics: Keep the number of flat surfaces facing the front of the car down to a
minimum. Sanding the body of the car smooth also helps cut down drag.
Mousetrap Race Scoring
2
Weight of Mousetrap
_________________
Weight of Car
Goal: Minimize weight
Minimize length
Maximize distance
Distance
_______
Length
Hints for Better Performance
1.
Reduce friction
2.
Use lightweight materials
3.
Amount of rotational inertia depends on the goal of the car.
4.
Test the lever arm length and wheel size to determine the
best for your type of car.
5.
Experiment early and often
Remember
Your final score is the total of the following
scores:
Score on technical report
Score on car design drawing
Score on the team interview
Mousetrap car race score
Don’t focus on the car race and forget the others!