Rat Trap Racer
Project #1
Land Transportation
Objectives
By the end of the unit, the students will be
able to:
1.
2.
3.
4.
State what Friction and Rolling Friction
are
State how aerodynamics plays a role in
your projects
Demonstrate how wheels play a role in
your projects success
Demonstrate how to Construct a Rat
Trap Racer for distance, speed, and
climbing ability
What is Rolling Friction
What is Rolling Friction?
Answer:
Rolling friction is caused primarily by the
interference of small indentations formed as
one surface rolls over another. This is the
idea behind the frictional forces involved
with wheels, cylinders, and spheres.
http://www.fearofphysics.com/Friction/fricti
on.html
What is Friction
Friction is the "evil" of all motion. No matter which
direction something moves in, friction pulls it the other
way. Move something left, friction pulls right. Move
something up, friction pulls down. It appears as if
nature has given us friction to stop us from moving
anything.
Friction is actually a force that appears whenever two
things rub against each other. Although two objects
might look smooth, microscopically, they're very rough
and jagged.
As they slide against each other, their contact is
anything BUT smooth. They both kind of grind and drag
against each other. This is where friction comes from.
But friction is not all bad. In fact, it has a lot to do with
life as we know it here on Earth. Without it, we
wouldn't be able to walk, sit in a chair, climb stairs, or
use a mouse to surf the web. Everything would just
keep slipping and falling all over the place.
What is Aerodynamics
Aerodynamics is the study of how air
flows under, over, and around an
object.
Thinking about how aerodynamics will
play a role in your vehicles in the
design stage will help your vehicle to
do better
Length of Car Matters
Although you might not think it the length
of the car matters for each different part.
For example you want the longest swing
of the rat trap arm for distance. Make
the car long and add extensions to the
arm. Remember that each revolution of
the axle is a revolution of the tires so the
larger the tires the further it will go. The
distance isn’t tested for speed so make
sure your vehicle doesn’t jump the line at
the beginning.
Traction and Friction
For the speed part you want friction at the
beginning so there is not burning out. It
is important your vehicles tires grab the
ground to give it that boost. For speed
you want a shorter wheel base and
shorter swing arm so it pulls the string
quicker. Wider tires help but you will still
need something to help grab the tiles.
Climbing
When it is time to construct your climbing
vehicle it is all about torque and speed.
You want your vehicle to twist the axle
aggressively so it is important your rat
trap uses both springs plus you will have
a little head start before the ramp so you
will be able to build some speed and get
some momentum
Challenge
Each student will design, sketch, and construct
their own Rat Trap Racer using various
materials and equipment in the Construction
Lab. The Sketches are random ideas of your
thoughts but there should be a minimum of 4.
From those 4 sketches select 1, draw it in detail
using a ruler and straight lines (no freehand
drawing). Be sure to include dimensions on
your Initial Drawings. When the project is
complete you will be required to complete the
evaluation form Your grade is broken down into
3 parts be sure to see the Evaluation part for
further explanation.
Challenge
Your grade for part 1 depends on how close to your Initial
Drawing you constructed your Rat Trap Racers. The closer it
resembles your Initial Drawing, the better your grade will
be. The more changes you make or extra pieces you add
the lower your grade will be. There are no partners on this
project; each student must make their own Car. Part 2 is
each student will be provided with one (1) rat trap for all
three projects. If your rat trap breaks during these projects
I will not provide you with another one. Each Rat Trap Racer
will be given one (1) week to be completed. If your vehicle
is not completed by the due date it will not be accepted at
all. If you have a vehicle that is halfway completed your car
is to be tested as is and you will be given no extra time to
work on them. If you are absent during these next weeks
you will be given only one day for each absence to make up
your work and it must be done before school at 7:10 in the
morning. You will not be given class time to make up
missed work. You cannot use the same car for all three
tests. The cars must look different but can use the same
principals if needed. These Rat Trap Racers must have a
minimum of 3 vinyl designs and numbers using three
different colors on each of them
Challenge

The first Rat Trap Racer to be built is for distance. It
absolutely has to go 30 feet minimum and from 30 feet
you will be graded on how far it can go beyond it.
Once your vehicle starts to move you cannot touch it or
have a friend touch it in any way to correct it. These
vehicles should estimate between 70 and 100 foot
distances if you take your time and try hard. Next is
for speed. We will time your car to see how fast it
goes in a 15-foot distance. These cars should get
times below 2 seconds. Once again this vehicle must
have at least 3 vinyl designs on it using three different
colors. You will have another 3 class periods to do this
part. Testing on the fourth day. Finally this project is to
go up the ramp the furthest distance with a minimum
of 10 feet. You will be graded based on how far up the
ramp beyond 10 feet it goes and once again you will
have to create 3 more different designs using 3 colors
of vinyl and place them on your car. You will have 3
class periods to work and the fourth is the test.
Challenge
On testing day you will be given the class
period to complete the objective. You will have
ample time to do this project and testing and
practicing is always allowed. There should be
no excuses as to why your project is not
completed and in working condition. There is
no power on testing day unless specified by the
instructor. You must do all work in class
unless I give you permission to take it home.
Be creative on this project and a nice design
and creative effort will only increase your
grade. Good luck
Procedures


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Brainstorm ideas and sketch 4 of them
onto 2 pieces of paper
Choose a design that you like the best,
draw an initial drawing of it with
dimensions
Use the supplied materials to create the
energy launcher
Finish the energy launcher using a filler
and any color paint you choose or vinyl
Evaluation



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Project Travels more than 30 feet
Project travels 15 feet in under 6
seconds
100 Points
Project travels up ramp 10 or more
feet
Project looks like Initial Drawing
with minimal changes
Student shows above average
effort
Student shows above average
safety skills
Evaluation






Project Travels more than 30 feet
Project travels 15 feet in under 6
seconds
75 points
Project travels up ramp 10 or more
feet
Project looks like Initial Drawing
with moderate changes
Student shows above average effort
Student shows above average
safety skills
Evaluation




Project passes 2 of 3
challenges
50 points
Project looks like Initial
Drawing with very noticeable
changes
Student shows above average
effort
Student shows above average
safety skills
Evaluation

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

Project does not work
Project does not look like
0 points
drawing at all
Student shows no effort
Student not allowed in class if
not demonstrating proper
safety skills