
Drag
Activity
If
so instructed by your teacher, print out a worksheet page for these problems.
Background:
Visit the
Glider Trajectory Problem and
the Vector Balance of Forces for
a Glider. Study the equation: L/D = 1/a where L stands for lift,
approximately equals the weight of the glider, and is measured in newtons;
D stands for the drag on the glider and is measured in newtons; and a
stands for glide angle and is measured in radians.
Weight and mass
are related. Weight is equal to mass times gravity: Fw = m * g where
Fw stands for weight and is measured in newtons (Note: W is also used
as a symbol for weight.), m stands for mass and is measured in kilograms,
and g stands for gravity and is equal to 9.8 m/s^{2}.
Radian measure is
another way of measuring the size of an angle. When we measure an angle
in radians we are measuring the length of the arc the angle cuts out
of a unit circle. A unit circle has a radius of one unit; therefore,
the circumference of a unit circle is equal to 2 times pi.
Problems:
Create a
spreadsheet that finds the weight of each glider, the measure of each
angle in degrees, and the drag on each glider at angles of 2, 3, 4, and
5 degrees.
Model Gliders

Mass

Fullsized Gliders

Mass

1

.5 kg

4

500 kg

2

.9 kg

5

900 kg

3

1.4 kg

6

1,400 kg

Questions:
 Compare the drag
between model glider 1 and the fullsized glider 4 for all four angles.
What conclusion can you draw?
 Based on your answer
in Question 1, would it be valid to use a model glider to study the
drag on a fullsized glider?
 What is the relationship
between glide angle and drag?
