Lecture 2

• what is an example of the space/time tradeoff

  when you compress an image you can reduce transmission time at the expense of CPU time to perform the compression and decompression, and quality of image
• what is an important aspect of trade-offs

  there is no single ‘right’ or ‘best’ solution; rather each solution comes with its own benefits and drawbacks.
• what is the equilibrium state of a system


  a state the system can stay in for an indefinite amount of time
• what is negative feedback


  if perturbed, system returns to equilibrium state
• what is positive feedback


  if perturbed, system does not return to equilibrium state
• what is abstraction

  "black-box" entities with simple interfaces - programmable devices that can be used effectively without having to completely understand the details of how they work.
• what is modularity


  composing systems of reusable, mix-and-match parts
• what does the iterative design process consist of

  • ideate
  • prototype
  • build
  • analyze
• what is transduction


  the conversion of one form of energy to another
• what are transducers


  devices which will convert between physical energy and electrical energy
• what does Chris Crawford describe interaction as

  an iterative process of listening, thinking, and speaking between two or more actors
• what are listening, thinking, and speaking during interaction analogous to in terms of computing

  input, processing, output
• whats the difference between digital and analog

  digital has a limited number of states (usually 2) - is the cat on the mat, whereas analog has a continuous range of multiple states - how heavy is the cat on the mat
• what are the two ways electrical current can flow through components

  serially or in parallel
• what is the defining characteristic of a series circuit

  there is only one path for electrons to flow
• the total resistance of any series circuit is equal to the sum of the individual resistances
• what is the defining characteristic of a parallel circuit

  all components are connected between the same set of electrically common points
• Total resistance in a parallel circuit is less than any of the individual resistances
• what is an example of positive feedback?


  when a herd of animals is disturbed and the animals scatter/disperse. This is positive feedback because some change was applied to the system and the system does not return to an equilibrium state
• what is an example of negative feedback?


  A thermostat that works by applying heat or cooling to the room only when it away from the desired temperature. For example, the thermostat heats the room up to the desired temperature and then shuts off. If the temperature were to drop again, the thermostat would turn on again. This is negative feedback because there is some change (heat applied) to the system (the temperature of the room). After the change is applied, the system returns to its equilibrium state