11. Make a large yoyo from two CD's with a short
piece of dowell or broomstick spacer cemented
between the disk centers.
12 If there is a quiet pond or lake nearby, verify
the laws of reflection by scaling the CD's over
the surface.
13. Stack about 50 of these CD's on a table top.
Measure the frictional force that is needed
to slide out one CD that is near the bottom of the stack.
then predict the force that is needed to slide out
others that are closer to the top of the stack.
14. Use the CD's as pucks floating on an air table.
Establish laws of collisions when pucks collide.
15. Have your physics students try some of the suggestions
for using CD's in the Physics lab. Ask them to come
up with some additional uses for CD's and submit their findings
for publication in "The Physics Teacher".
Herb Gottlieb from New York City
(Where our students of the past were anxious to accept challenges
to their intellect"