Slinking Slinkies
Related Links
Project Summary
| Difficulty | 3 |
| Time required | Very Short (a day or less) |
| Prerequisites | None |
| Material Availability | Readily available |
| Cost | Very Low (under $20) |
| Safety | No issues |
Sponsor
| Sponsored by a generous grant from Seagate |
|
Objective
In this experiment you will use an inclined plane to test the walking speed of two differently sized Slinkies.
Introduction
The Slinky is a classic American toy, with roots in Pennsylvania. The inventor of the Slinky was a retired Navy engineer named Richard James. He initially thought the bouncy springs would be useful for supporting sensitive instruments onboard rocking ships at sea. But when the Navy had no interest in his springs, his wife Betty had a better idea. She thought up a catchy name and Slinky the toy was born in 1945.
 |
| The classic Slinky— fun for all ages! |
The Slinky has a unique ability to "walk" down steps or a sloping surface. This type of sloping surface is also a simple machine called an inclined plane. How will these two mechanical systems interact? In this experiment you will make a simple inclined plane to test the walking speed of two differently sized Slinkies, the original Slinky and the Slinky Jr.
Terms, Concepts and Questions to Start Background Research
To do this type of experiment you should know what the following terms mean. Have an adult help you search the Internet, or take you to your local library to find out more!
- inclined plane
- coil
- diameter
- angle
- critical angle
- protractor
- How do I build an inclined plane?
- What angle is best for the Slinky to slink down the inclined plane?
- Will Slinkies of different diameters use the same angle?
Bibliography
- Read about how the Slinky was invented from this site for young inventors at MIT:
MIT, Date Unknown. "Inventor of the Week: Slinky," Lemelson-MIT Program: Massachusetts Institute of Technology, School of Engineering. [accessed February 10, 2007] http://web.mit.edu/Invent/iow/slinky.html - Check out the Slinky Science Teaching Guide, developed by engineers at Conoco Phillips:
TeachingTools.com, 2003. "Racing Slinky's," Slinky Science Teaching Guide, Conoco Phillips [accessed February 10, 2007] http://www.teachingtools.com/Slinky/slinky.html - This project was based on a project by Erica Byrne and maintained by Bob Barrett:
Byrne, E., Date Unknown. "Slinky Walking Speed vs. Angle," Slinky Home Page [accessed February 10, 2007] http://153.42.40.32/~barrett/speed.htm
Materials and Equipment
- large, dense cardboard sheet or a piece of plywood
- stack of books
- metal Slinky
- metal Slinky Jr.
- protractor
- stopwatch
Experimental Procedure
- For this experiment you will need to write your results in a data table. You will need to write down the type of Slinky used, the angle of the plane, the number of flips, the time in seconds and the Flips per Minute:
Slinky Angle Number of Flips Time (seconds) Flips per Minute 30o Slinky Jr. Angle Number of Flips Time (seconds) Flips per Minute 30o - To make your adjustable inclined plane, rest one end of your plane (either a stiff sheet of cardboard or a piece of plywood) on a stack of books. To adjust your angle, simply add or remove books to the stack. Adding books will increase the angle and removing books will decrease the angle.
- Measure the angle formed where the base of the plane meets the floor with a protractor. Begin by setting the angle to 30 degrees.
- Get your stopwatch ready and set the Slinky at the top of the plane.
- Release the Slinky and start the stop watch. Count the number of flips and stop the watch when the Slinky completes its last flip before the end of the plane. Write down the number of flips and the time in seconds in your data table.
- You will calculate the speed of the Slinky in Flips per Minute. To do this calculation, divide the number of seconds in a minute (60) by the number of seconds you measured. Then multiply your answer by the number of flips you counted.
For example, if I counted 3 flips of my Slinky in 10 seconds, Write this calculation in your data table.
then 60 / 10 = 6 and 6 x 3 = 18 Flips per Minute. - Test the Slinky Jr. at the same angle, make your measurements and calculations, and record your data.
- Change the angle of the inclined plane and repeat the experiment with each Slinky.
- Make a graph of your results by putting a scale of the angle on the bottom (x-axis) of the graph and a scale of the walking speed in Flips per Minute on the left side (y-axis) of the graph. Make a dot for each data point on your graph. Make the Slinky dots in one color and the Slinky Jr. dots in a contrasting color. Then connect the dots for each respective color.
- How do your results compare? Is the bigger Slinky faster or slower? Were the movements the same or different? How did the walking speed change as the angle increased or decreased?
Variations
- In this experiment you compared the movements of two differently sized Slinkies, but you can also compare Slinkies made of different materials. Try the experiment again with the plastic Slinky and Slinky Jr. Are your results the same or different?
- There are many ways to use a Slinky for a science experiment:
- Put the two ends on the floor and jump to find out how you can use the Slinky as a wave detector.
- You can use the Slinky to study compression waves by wiggling it back and forth.
- If you bang on the Slinky you can generate sound. Can you make different pitches?
- Slinkies have also been used as giant antennae.
- What else can you think of?
- Advanced students can use linear regression to further analyze the data. Can you define an equation that expresses the relationship between the angle of incidence and the walking speed for this system? What is the error in your experiment? Are your results significant?
- For more science project ideas in this area of science, see Mechanical Engineering Project Ideas
Credits
Sara Agee, Ph.D., Science Buddies
Sources
This project was based on a project by Erica Byrne and maintained by Bob Barrett:
Byrne, E., Date Unknown. "Slinky Walking Speed vs. Angle," Slinky Home Page [accessed February 10, 2007] http://153.42.40.32/~barrett/speed.htm
Last edit date: 2007-04-03 23:00:00
