Download The Planet Race

The Planet Race
Objective: To show the effect of distance on the orbiting speed of various
planets.
Standards: Objects in the Sky (sky object properties, locations, and movements)
and Earth in the Solar System (position, properties of sun, earth, and the other
planets).
Materials: one metal washer and a piece of string one meter in length.
Procedure:
(1) Secure the washer to the end of the string by tightly tying it.
(2) Hold onto the end of the string and extend your arm outward.
(3) Swing your arm in a circular motion.
(4) Spin the washer as slowly as you can while still keeping the string
extended tightly.
(5) Hold the string in the center and repeat step four.
(6) Hold the string about ten inches away from the washer and repeat step
four.
***This demo should be performed outside or in an open area where
nothing will be interfered with by the washer and string***
Science Behind It: Students will have observed that as the length of the string decreases,
the washer must be spun faster to maintain the tightness of the string. The students
should also notice that the washer spins lethargically around in its path when the string is
longer but spins much faster when the string is shorter. This demo directly relates to the
slower and faster movement of planets that differ in distance from the sun. As the
distance of a planet increases from the sun, the affects of the sun’s gravity on that planet
decrease, therefore causing a decrease in orbital speed because of less pull towards the
sun. Mercury has the fastest orbit around the sun as it is the closest one, while Pluto has
the longest orbit being that it is the furthest planet from the sun.