*tick, tick, tick, tick, tick*

Newton's Cradle is the archetypal executive toy, found on the
desks of doctors, lawyers and
businessmen everywhere.

Consisting only of five stainless steel balls suspended by
two strings apiece (to prevent lateral movement), Newton's
Cradle was originally devised to illustrate conservation of
momentum and energy.

Newton's Cradle demonstrates that the momentum of *x*
number of pendulums on one side will be transferred
(through one or more seemingly stationary pendulums) to
*x* pendulums on the other side.

--+-+-+-+-+-- --+-+-+-+-+--
/ | | | | | | | | \
/ | | | | --> | | | | \
/ | | | | | | | | \
@ @ @ @ @ @ @ @ @ @

--+-+-+-+-+-- --+-+-+-+-+--
/ / | | | | | | \ \
/ / | | | --> | | | \ \
/ / | | | | | | \ \
@ @ @ @ @ @ @ @ @ @

--+-+-+-+-+-- --+-+-+-+-+--
/ / / / | | \ \ \ \
/ / / / | --> | \ \ \ \
/ / / / | | \ \ \ \
@ @ @ @ @ @ @ @ @ @

A more complicated two-dimensional version of this system, the

Lattice Newton's
Cradle, consists of

five rows of five pendulums.

To learn more about conservation check out the Three Laws of
Thermodynamics.