You are part of a team of engineers who have been given the challenge of building a working clock based on a pendulum. You'll need to be able to set the clock at two speeds, and will have to figure out how to adjust the materials you are using to make the clock run faster and slower. You'll use every day items such as string attached to a rubber ball to serve as your pendulum. How you design your clock and what materials you use are up to you!
Read the handouts provided to you by your teacher, and if you also have access to the internet visit one of these sites to gain more understanding in the history and operations of pendulum clocks:
A Walk Through Time (www.nist.gov/pml/general/time/)
Clockworks -- from Sundials to the Atomic Second (www.britannica.com/clockworks/startpage.html)
Parts of a Pendulum
A pendulum is relatively simple, and consists of only a few components: a length of string or wire, a bob or some type of weight, and a fixed point where it is attached to a solid object. Remember that a string may swing in various directions, but for the clock, you'd want to fix it to something, or use another material to keep the motion along a single plane -- back and forth, not wobbling.
You have been provided with many materials from which to design and build your own pendulum clock. Remember that your clock doesn't need to be perfect, but does need to be able to measure time fairly consistently. You can keep a chart or measurements of the "period of the pendulum" -- which is the amount of time that it takes a pendulum to complete one full back-and-forth swing. Consider which materials you would like to use, and list them in the box below. On a separate piece of paper, draw a diagram of the clock you intend to build.
Pendulum Time Student Worksheet:
Build a Pendulum Clock
Measure the length of string you plan to use to attach your weight to in order to form a pendulum. You'll need to keep track of this when you are adjusting the speed at which your pendulum moves. You may wish to weigh your pendulum weight as well to help you set your clock to work at two different speeds
Build it! Test it!
Next build your clock and test it. You'll need to be able to record time with your clock and set up your own scale or chart to keep track of the pendulum movements. Use a stop watch to see how many swings of the pendulum occur in 10 seconds. You'll also need to speed up or slow down your clock. (Hint: adjusting the length of string attached to the pendulum might assist with this task.) You may share unused building materials with other teams -- and trade materials too. Be sure to watch what other teams are doing and consider the aspects of different designs that might be an improvement on your team's plan.
Complete the reflection questions below:
1. How similar was your original design to the actual clock your team built?
2. If you found you needed to make changes during the construction phase, describe why
your team decided to make revisions.
3. Was your clock able to measure time at two different speeds? What measurement scale did you devise to measure time with your clock?
4. Which clock that another team made was the most effective or interesting to you? Why?