April 19, 2010
Science Fair – RC Airplane Material
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. 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.
Hewitt, Conceptual Physics, p32
Adapted from Weight – An Accurate, Up-to-Date, Layman’s Definition, Roy Bishop, The
Physics Teacher, Vol. 37, p. 238-239 (April 1999)
This experiment highlights all four learning targets: interpreting data, performing a scientific
investigation, evaluating experimental results, and communicating scientific ideas.
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.
Sheet of plastic
Sheet of cardboard
Sheet of Styrofoam
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.
Material Weight (grams)
Material Coefficient of Kinetic Friction
Material Angle (degrees)
See attached sheet.
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.