| Introduction:
Making a mousetrap car is a
mechanical engineering challenge often used as a competition for
students from 5th grade up to the second year college.
A mousetrap powered car is a
vehicle that uses a mouse trap for a motor and a string to
transmit force. In this method one end of a string is
attached or tied to the arm on the mousetrap and the other
end of the string is wound around an axle.
By winding the string around
the axle the mouse trap's spring is stretched and now you
have your stored energy. As the mousetrap car is released
the mouse trap pulls the string off of the axle causing the
wheels to turn and off the vehicle goes. |
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Some students may prefer to cut all
the woods themselves and design their own car; however, most
students and teachers prefer to get all the parts in a kit and make
changes as they need.
With this project students can explore:
- A simple propulsion method
- Basic gluing techniques and design concepts
- Concept of stored energy
Items Needed:
Mousetrap Car
Kits usually come with parts, cut to size and ready to use.
The picture bellow shows the materials you usually
find in a mousetrap car kit from MiniScience. Kit includes at least 16
wooden parts cut to size in addition to the mousetrap,
string, rubber bands and eyelets.
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Materials Checklist:
Before using the kit please verify the content
with the parts in this picture.
In addition to the kit
parts you will need:
- White glue or wood
glue
- Grip Pins
- Sand Paper (Medium
Grit)
- Tape
- Latex Paint
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Teacher Preparation:
During construction of the mousetrap vehicle, students
can experiment and
comprehend methods of power transfer, using glue, sanding, painting . It is up to the teacher to make sure this background information is
provided to students in some manner.
Background
Before invention of gas
engines, cars were pulled by horses or other animals.
Now gas burning engines are the most popular drive in
cars. Inside the engine, the chemical energy stored in
fuels are released in the form of hot gases and convert
to mechanical force in cylinders.
During the history many
other attempts have been made to use other forms of
energy to drive a car. In this experiment we try to use
the energy stored in a spring (Mousetrap String) to
drive a model car.
Assembly Procedure
Prepare your workplace by mounting a cardboard
and a wax paper on the top of it. This will protect your environment or desk to
be damaged by pins, glue or pint.
| Remove sides
and floor parts from the die-cut sheets. Apply
glue to all sides and floor where they contact
each other, and pin in place as shown. |
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| Apply glue to
surfaces of back panel and nose block where
surfaces contact sides, and pin as shown. Allow
the glue to dry thoroughly. Use sandpaper to
sand off top edge of nose block. |
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| Glue
aerodynamic wing into notches at rear of sides.
Pin in place until dry. Now is the time to pint
and apply numbers, names, etc. to your racer
before proceeding to the next step. |
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| Push eyelets
slowly into sides while holding fingertips over
inside hole to help prevent splintering of the
wood when eyelet comes through the inside. |
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| Wrap a piece
of sandpaper around an axle and use it as a file
to create a notch in the short dowel rod, as
shown. After notching, set aside until needed
later. |
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| Insert the
axles into the sides. Axles must rotate freely
in eyelets. If necessary, remove axle, sandpaper
it until round and smooth, and test it again. |
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Take the remaining four
eyelets and slide onto axles, as shown. Be sure the same
amount of axle is sticking out of eyelets on each side.
There should be a slight gap between the eyelets, as
shown.
Glue eyelets to axle as
shown.
| Assemble the
rear wheels, gluing the die-cut parts as shown. |
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| Carefully
press wheels onto axles. The axles must stick
through the wheels about 1/8". Place a drop of
glue on axles on both sides of the wheels. Spin
wheels to check for wheel wobble and adjust
before glue dies. |
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| Glue the
mousetrap to the floor. You can now paint the
wheels if desired. |
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| Apply glue in
notch of the small wood dowel and press against
rear axle until glue sets.
Note: Apply a
second coat of glue around joint after first
coat is thoroughly dry. |
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Tie string to the trap
bail and glue. Tie an approximately 1/2" loop at end of
string and glue. This slips over the short dowel rod.
Stretch rubber bands (Tires) around rear wheels.
Set the
mousetrap to power your racer. (Adult Supervision
required to set trap)
| A. Lay catch
arm of mousetrap on aerodynamic wing. Place loop
over end of notched dowel. |
B. Lift trap
bail rearward and press it flush against the
wood of the mousetrap while turning rear wheels
backward to wind the string around the rear
axle. |
| Keeping
fingers clear of the area where the trap bail
strikes the wood of the trap, bring catch arm
forward and position it under the catch plate
and carefully release it so that it is held down
by the catch plate.
To release the
energy, now stored in the spring supplying power
to your racer, press the catch plate with a
stick, pen, ruler or similar item. NOT A FINGER.
and quickly withdraw the item you used. |
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| If you don't
have this kit, you can order it now! It is
available both as a single pack and class pack.
Secure
Online Store
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