Aakash Soni
Alan Strimbu
April 19, 2010
Science Fair – RC Airplane Material
Background Information
There is quite of bit of background knowledge that it is necessary to know in order to complete this experiment successfully. Some different physics components that are important to understand are weight, drag, and coefficient of kinetic friction.
There are two different definitions for the force of weight. Some physicists and engineers believe that weight is the force of gravity upon a body, while others believe that an object’s weight equals the force required to support it, or basically, what a scale reads.
[1][2] Weight changes depending on where an object is in the universe; as gravity changes, so does an object’s weight.
Weight can be determined by multiplying mass by gravity. More practically, it can be determined by setting an object on a scale or hanging it from a spring scale. Gravity pulls the object downward and the scale measures the resulting downward force.
Drag, or air resistance, refers to all of the forces that oppose an objects motion through a fluid.
For example, as an object moves through the air, air molecules hold the object back. To substitute for drag, we used the coefficient of kinetic friction. To measure this value, one can use a spring scale and pull it across the surface of a material and measure the amount of newtons that the scale reads.
1
Hewitt, Conceptual Physics , p32
2
Adapted from Weight – An Accurate, Up-to-Date, Layman’s Definition , Roy Bishop, The
Physics Teacher, Vol. 37, p. 238-239 (April 1999)
Objective
This experiment highlights all four learning targets: interpreting data, performing a scientific investigation, evaluating experimental results, and communicating scientific ideas.
Safety
There are not many safety issues involved in this lab. However, safety goggles can be worn to prevent the possibility of any freak accidents occurring.
Materials

Sheet of plastic


Sheet of cardboard

Sheet of Styrofoam

Spring scale

Box cutter

Gram scale

Protractor

RC airplane
Procedure
1.
Cut identical rudders and elevators out of plastic, cardboard, and Styrofoam.
2.
Weigh each pair of rudder and elevator on the gram scale.
3.
Test the coefficient of kinetic friction for each material using a spring scale.
4.
Attach the rudder to the airplane for each material and measure the maximum angle which it can turn.

Data
Material
Cardboard
Plastic
Styrofoam
Weight (grams)
42
47
38
Material
Cardboard
Plastic
Styrofoam
Coefficient of Kinetic Friction
.38
.20
.44
Material
Cardboard
Plastic
Angle (degrees)
42
48
Styrofoam
Graphs
See attached sheet.
Data Analysis
33
Through testing each of the different materials, we determined that cardboard would be the best solution to use for a rudder and elevator for a radio controlled airplane. To determine this we compared the weight of the rudder and elevator, the coefficient of kinetic friction for each material, and the maximum angle that the rudder and elevator could turn when attached to the plane. While cardboard was not the best in every category, it was never the worst either.
Cardboard was the most well rounded of the three materials. Plastic had the lowest coefficient of kinetic friction, however it was also the heaviest. Similarly, Styrofoam weighed the least, but it had the highest coefficient of kinetic friction.
Conclusion