5-Second Timer Project

Introductory experimental design mini-project.  Students build a device that mechanically times a 5-second interval.

5-Second Timer

Objective:

Your assignment is to use any objects you can find to make a mechanical timer that can measure an interval of exactly five seconds.

Rules:

  1. Your timer may not use electricity.
  2. Your timer may not use a clock.
  3. Your timer may not be an “off-the-shelf” item.  If you use a pre-made device or object, you need to modify it in some substantial way that affects how you use it to measure five seconds.  (Ask in advance if you’re not sure.)
  4. If your timer does something repetitive, you may count a specific number of repetitions. For example, if you have a ball on a string that winds around a pole, you may measure five seconds by how long it takes the ball to go around the pole some specific number of times.
  5. Your timer may not require human interaction after it has started (except for counting repetitions of some action, as described in rule #4 above).
  6. You must declare in advance how your timer will indicate when five seconds has elapsed.  For example, having a gadget that flops around on the floor randomly while you count "one-Mississippi, two-Mississippi..." is not acceptable.
  7. You have a maximum of two (2) minutes to set up your timer.
  8. You may work individually or with one partner.  No groups of three or more.
  9. Elapsed time will be measured by Mr. Bigler, using a hand-held stopwatch.  Because of the limits of human reaction time, results within 0.1 s of each other will be considered equivalent.  (This may result in multiple winners.)

Some Suggestions:

  • Dominoes (but watch out for the 2-minute set-up rule!)
  • A marble and a track
  • A Slinky on a flight of stairs
  • A pendulum
Last modified: Monday, 11 November 2013, 1:13 PM