
Orbital
Simulator  Classroom Activity The
simulator at http://observe.arc.nasa.gov/nasa/education/reference/orbits/orbit_sim.html
allows students to investigate Kepler's three laws of planetary motion.
Ask students to work in small groups to explore the simulator, and to
keep a record of what they do. On the Third Law simulation, bear
in mind that the relationship (period squared) ~ (radius cubed), when
translated into mean orbital speed, becomes (speed squared) ~ (1/radius),
so a smaller radius implies a higher speed.
The following are possible
questions for classroom discussion:
A. First simulator: The Law
of Ellipses:
 At what point does the
satellite move the fastest?
 At what point does the
satellite move the slowest?
 The Earth is at one focus
of the ellipse. What is at the other focus?
 What does the orbit look
like if the eccentricity is set at one of the values for a planet about
the Sun?
B. Second simulator: The Law of
Areas:
 Which end of the ellipse
is the yellow section thinnest on?
 Which is it the thickest?
 The yellow section shown
will always be the same area, although sometimes it is thinner and sometimes
it is thicker. How can this be the same area, yet have a different
shape? (You might have to demonstrate conservation using the same amount
of liquid in two differently shaped cups.)
C. Third simulator: The Harmonic
Law:
 How does the period of
revolution of the Shuttle compare with that of a geosynchronous satellite?
With the period of the Moon?
 While the space shuttle
orbits the earth, it doesn’t speed up or slow down by accelerating
like a car. Instead, it moves to a higher or lower orbit.
What does it need to do if it wants to speed up?
 What does it need to do
to slow down?
