Grade Level/Subject
High School physics (first year, all levels)
Unit
Waves
Enduring
Understanding
SOL Objectives
All waves, regardless of origin or type, transmit
energy from one place to another and share a
common set of characteristics that explain their
behavior.
PH.8 The student will investigate and
understand wave phenomena.
Key concepts include
a) wave characteristics;
b) fundamental wave processes; and
Title
Wave properties with Super Slinkies
Lesson Objective
To develop understanding of core wave
phenomena through manipulation of slinky
waves, and to discover the key concept of wave
speed being determined by the medium
3
Inquiry Level
Materials Required
Super slinky, stopwatch, metersticks or tape
measure.
Wave Properties with Super Slinkies of Science!
The purpose of this lab is to study basic wave properties that are
common to all waves and to most forms of simple harmonic
oscillation.
SLINKY WARNING!
Slinkies can easily become twisted
and deformed. The leading cause of
death among slinkies is accidental
tangling. This happens when overzealous and under-cautious teenagers
let go of one end of a stretched slinky.
Only you can help stop this senseless
carnage! Be careful!
0) Create a continuous wave train by moving your hand back and forth and back and forth. Notice
the waves moving outward from your hand, down the slinky. Draw on the axis below a long wave
train of continuous waves and label the wavelength and the amplitude of the wave. Label the crest
and the trough.
Waves are not just nice things to watch on the beach. Waves are a part of modern society, and we
need to be able to design and control the waves around us. This can apply to musical instruments,
cellular communication, light, and many other forms of waves. For each of the wave properties we
study (amplitude, frequency, wavelength, period, speed), determine a way to double that parameter.
Measure it to ensure that you can in fact double (or half) the value. Describe how you can go about
doubling it, and record your data along with the method for each.
1) Amplitude (how many meters from the rest position of the slinky to the peak of one wave).
2) Frequency (f) (how many waves pass a given spot each second).
3) Wavelength (λ) (how many meters from crest to crest).
4) The period (T) (how many seconds for a complete wave cycle to pass by a given spot).
5) Wave speed (v) (the speed at which the wave traveled from one end of the slinky to the other).
6) Describe below any relationships you uncovered between the different wave properties, and how
you believe they are connected.
Teacher Notes:
This inquiry lab is a first-day, instruction-free lab to start a wave unit.
Though this looks like just a “go play with slinkies” lab, it can become quite challenging for
students. The key here is that they have to actually measure each parameter. This has the
advantage of not just requiring them to demonstrate that they can make a wave, but also know how
to measure it.
If they can figure out how to double a parameter, that means they have a pretty good understanding
of that parameter.
Most importantly, however, they will discover (on their own!!!) that they cannot change the wave
speed by shaking the slinky faster. Be careful because MOST groups will simply claim that they
were able to do it, without actually measuring it. Or even fool themselves with sloppy wave making,
and claim that a slight measured increase is close enough to a doubling.
That is why the signature box appears next to the wave speed item. For this one, it is important that
the teacher observe and ask questions to see if a student has actually figured this out.
It might be helpful for certain groups to demonstrate a crisp “wave pulse” in the slinky, since timing
an extended object can be difficult. Making a “flick” in the spring may be enough to observe a pulse
traveling the entire length.
The goal of this lab is for students to discover for themselves the most important relationship in
waves, that the wave speed is determined by the medium.
Don’t give them the wave equation. They may figure it out (at least partially) through this lab, but a
second inquiry lab (changing mediums) will help them to build this equation for themselves. Let
them enjoy the process of discovery.