Cardboard Racer
Introduction: Cardboard Racer
This project will describe the process of making a functional cardboard racing car that is powered by an elastic band and with it how STEM (STEAM), [not forgetting the Arts]; can be applied.
Science will explore Newtons 3 laws of motions.
Technology - Practical application of the Science using the car to perform experiments.
Engineering - Design and building the car.
Arts - Creative expression to customise and individualise the car by modifying it visually whilst maintaining functionality.
Maths - Calculation used to generate numerical data for analysis.
Supplies
Corrugated Card Board (370 x 230 x 4 mm) * 3
Scissors
Cutting Blade
Clear Adhesive Tape
Glue
Ruler
Pencil or Pen
Elastic Bands * 5
Cloths Pegs as required.
Bamboo Skewers * 2 (160 mm min)
M4/10mm screw * 2
M4/20mm threaded standoff
M4/20mm screw
M4 washers * 6
4 mm drill bit
Bradawl
Step 1: Newtons 3 Laws of Motion
What are Newtons 3 law of Motion.
1: An object at rest or in motion will continue to do so unless acted upon by an external force.
The car continues in motion once the initial force is applied but will eventually come to a stop as a result of frictional forces. Frictional forces can be significantly reduced by the use of bearings and rolling on a hard surface.
2: When a force acts on an object, it will cause the object to accelerate. The larger the mass of the object, the greater the force needed to cause it to accelerate. 668
Therefore, force = mass x acceleration.
The mass is constant but we can change the force to cause greater acceleration.
3: For every action, there is an equal and opposite reaction.
The more you pull the elastic the more force it generates. The applied force is stored as potential energy and is released as kinetic energy with an equal and opposing force.
Step 2: Experimentation
Newtons 2nd law states that Force = mass x acceleration
The mass of the car of 0.115kg
If it accelerates at 1m/s then the force required is 0.115 * 1 = 0.115 N (assuming no losses in the system)
m/s * 2.237 = mph.
Greatest acceleration will occur upon release and thereafter reduce due to external forces.
If you time the car over a fixed distance you will get an estimation of speed.
For acceleration (1m/s), mass (0.115kg), and the measured displacement of the elastic (18cm).
Elastic Potential Energy (Joules) = 1/2 * Force (N/m) * Elastic displacement^2 (m)
The Force is the spring constant = F/dX = 0.639N/0.18 = 3.55N/m
EPE (Joules) = 1/2 * (3.55N/m * (0.18m^2)) = 0.0575J
Velocity = sqrt((2*EPE)/kg) =sqrt((2*0.0575)/0.115) = 1 m/s
More force is required to overcome frictional losses & elastic efficiency in the system 0.639N versus 0.115N.
Further experiments looking at the effects on distance and speed can be conducted.
1: With stronger and weaker elastics. (greater or weaker force).
2: For variation in mass..
3: On hard floors (wood/cushion floor) compared to carpet.
4: The ratio of elastic stretch.
Review the data using Excel with charts to visualise the results pictorially and numerically.
Step 3: Main Body - Part 1
This is the body and chassis of the car all in one..
Its designed for rigidity in the 3d form with minimal pieces.
Orientate the piece of card (370 x 230 mm), with the long edge horizontally.
With the pencil and ruler, proceed to mark the card as per the diagram.
Once the card has been marked, proceed to cut the card with a sharp blade using the ruler as a guide
Folds are marked with dotted lines
Holes are marked with a cross.
Step 4: Main Body - Part 2
Once the pattern for the car has been cut out folds are required to give it shape and strength.
Align the centre line on the card with the edge of a table or box and carefully apply pressure close to the line on the card overhanging the edge of the table/box, pushing the card down to form an angle of ~60 degrees.
Proceed to bend the two short tabs inwards to an angle of ~90 degrees. 343