James P Houghton

James Houghton - Some Simple Systems

Some Simple Systems

15 Mar 2012

Posting so far has been pretty theoretical, so its time to start getting practical. The definition we arrived at last time was:

System: A set of objects that interact with each other to create a function not present in the individual objects.

Based on that definition lets start looking for systems. We should start with the most simple systems we can imagine, just to practice identifying them. I’ll keep posting descriptions of systems encountered in normal life, but here are a few from my desk to get started:

A ballpoint pen Its parts are:

  • A small metal ball
  • A metal point
  • An inner plastic sleeve
  • Ink
  • An outer plastic sleeve
  • The interactions between the parts are:
  • The ball is held in the metal point
  • The point is attached to the inner sleeve
  • The ink clings to the sleeve, point, and ball
  • The outer sleeve surrounds the inner sleeve, point, ball, and ink

The functions of the pen are:

  • To store ink in an accessible form
  • To supply a measured quantity of ink to a fine point
  • To allow a human hand to apply the ink to paper

It is interesting in this case also to note that one of the functions ‘To allow a human hand to apply the ink to paper’ implies that the pen is intended to be a part of an even larger system - involving a hand and paper. In a future post we’ll talk about how we choose system boundaries.

Another tool for modifying paper: A hole punch Its parts are:

  • A metal handle
  • Steel Punch Pins
  • Springs
  • A base
  • Brass Hinge pins

The interactions between the parts are:

  • The hinge pins connect the handle to the base and allow 1 degree of rotation
  • The springs press the punch pins upward from the base
  • The handle presses the punch pins down toward the base

The functions of the hole-punch are

  • To apply a shear force to paper in a hole shaped pattern
  • To amplify the force of a hand upon the handle

This example contains some subsystems - groups of parts which meet the definition of a system. For instance the hinge, handle, and pins constitute a lever, providing the force multiplying function. We’ll address identifying subsystems and how they fit into larger systems in a later post as well.

© 2016 James P. Houghton