Name: _______________________________________ Block: __________ Date: ___________
IP 614
Catch a Wave Lab:
ie. Wiggle and Observe Springs in the Hall
Purpose:
 This lab is designed to explore different properties of waves in springs.
Prior Knowledge:
 You need to follow directions that include the following vocabulary: amplitude,
reflection, wavelength, medium, pulse
Materials:
 Each group needs a meter stick, three people, a stopwatch, and a long spring
(telephone cord or metal spring)
Roles:
 Two Spring Holders and One Recorder/Timer
 When you return to the classroom, everyone in your group will work together to
make sure that everyone fills in his or her lab sheet.
Observe:
General Procedure:
 Get together with your partners and gather materials listed above.
 Follow the directions in each section. Answer the questions in the space provided,
using proper writing and clear diagrams.
 Return to class when done.
Side –to-side
Pulse
Amplitude
Width
(related to wavelength)
forward & backward
Standard(s): 4.1, 4.2, 4.3, 4.4
TA: _____________
Independence Level: __________%
Assistance, coaching, prompting: __________________________________________________
Part A: Experience Pulses and Waves Using a Long Spring
1. Have two people sit on the ground holding the long spring.
2. Carefully– so as not to get it tangled or kinked – stretch it out on the floor.
3. One of you should give the spring a rapid jerk by shaking it to one side then back so that you
create a wave pulse that travels to the other end. Be sure your partner holds his end fixed.
4. Repeat several times, observing what happens to the wave pulse as it travels to your partner
and back.
5. What happens to the amplitude (height) of the pulse as it travels away from its source? (Circle
one)
 The amplitude stays the same size, gets smaller, or gets larger as the pulse travels away
from its source.
6. In what direction does the pulse move and in what direction do the individual coils of the
spring move?
 The pulse moves (Circle one)
side to side
forward and backward to people on ends
 The spring moves (Circle one)
side to side
forward and backward to people on ends.
7. Do the pulse and the spring move in the same direction or perpendicular to each other?
 The pulse and the spring move: (circle one) in the same direction
perpendicular to each other
8. What happens to the wavelength (width) of the pulse as it travels to your partner? (Circle one)
 The wavelength stays the same size, gets smaller, or gets larger as the pulse travels to your
partner.
9. Rather than sending a single pulse, shake your hand side-to-side to send multiple waves down
the spring.
10. Thinking about energy, why does the amplitude of the wave pulse decrease as the pulse
travels? Where does the energy go?
Part B. A Relationship between Tension and Wave Speed:
1. Does the tension in the spring have anything to do with the speed of a wave? Make a
hypothesis: ___________________________________________________
2. Have two people sit on the ground holding the long spring. One person should make a pulse
that goes to the other end and comes back. Move closer together and make another pulse.
Repeat until you find the shortest distance over which you can observe the pulse traveling
away and returning to its starting point.
3. Measure the distance between the 2 people holding the spring and record it on the line labeled
"Short" for LENGTH.
4. The timer should time how long it takes for the pulse to go all way to the other person and
back. (The timing should stop when the person who made the pulse gets it back.) Do this a
total of three times. Record your times in the chart below.
5. Then stretch the spring to find the longest distance over which you can observe the pulse
traveling out and coming back. BE CAREFUL! Do not overstretch the spring, nor let go of the
end and end up tangling the spring.
6. Measure the distance between the 2 people holding the spring and record it on the line in the
table labeled "Far" for LENGTH.
7. Again, find the round trip time for the pulse three times.
8. Now find a length about halfway between the other two lengths. Get similar data and record it
in the row labeled "Medium."
9. Calculate the average time and speed for each length and record in the table below.
Length
(m)
Distance
(m)
Time #1
(s)
Time #2
(s)
Time #3
(s)
Average
Time (s)
Speed
(m/s)
Short
Medium
Far
10. As you stretched the spring, its tension grew. How is the speed of the wave related to tension?
 When the spring has more tension, the pulse travels with a ________________ speed.
 When the spring has less tension, the pulse travels with a __________________ speed.
Part C. A Relationship between Amplitude and Wave Speed.
1. Does the size of the pulse (its amplitude, how wide you snap it) have anything to do with the
speed? Make a hypothesis: ___________________________________________________
2. Hold the two ends of the spring a distance apart such that you can get a good pulse going from
one end to another.
3. Measure the distance. How long is the spring? _____________ m
4. If a wave makes a round trip from one end to the other and back again, how far has the wave
traveled? ______________m (This is the TOTAL DISTANCE.)
5. Now practice making pulses with a big amplitude, a medium and a small.
6. Then measure the round-trip time for a big pulse three times, medium three times, and small
three times. Record these as you measure them.
7. Calculate the average times and speeds for each size pulse.
Size of
Pulse
Time #1 (s)
Time #2 (s)
Time #3 (s)
Average
Time (s)
Speed (m/s)
Big
Medium
Little
8. Does the amplitude affect the speed significantly? (Circle one) yes no
a.
If yes, what is the relationship?
 Larger pulses have _____________________ speeds.
 Smaller pulses have ____________________ speeds.
9. If speed does change, what could account for the faster (or slower) speed? (Hint: Think about
Part B “Tension and Wave Speed”. Does tension change with extra large or small pulses?)
Mechanical Wave Summary
Important Definitions:
 A wave transfers ___________________ from place to place.

If something has energy, it has the ability to do ___________________, which means
it can apply a __________________ that makes something ___________________.

Earthquake waves can knock down buildings, which means the wave is doing work on
the building.

Describe another example of a wave doing work:
 Mechanical waves

A medium is the ______________________ through which waves can travel.

Mechanical waves need matter to travel

In other words, mechanical waves require a ______________________.

Examples of mechanical waves: sound waves, water waves, spring waves, jump rope
waves, stadium waves

If sound waves are mechanical, can they travel through a vacuum?

There are 2 types of mechanical waves: transverse and longitudinal
 A transverse wave is a wave in which the particles of the medium move
____________________________________ to the direction of the wave (energy) motion.
 Anatomy of a Transverse Wave:
 Crests: _________ and _______. Troughs: ________ and ________
 Amplitude: A measure of the amount of ____________________ being transported.
o Height from the dotted line to Point _____________ OR
o
height from the dotted line to Point ________________ OR
o height from the dotted line to Point ________________ OR
o height from the dotted line to Point ___________________.
 Wavelength: Distance from Point A to Point _________________ OR
o Distance from Point B to Point ________________ OR
o Distance from Point C to Point __________________ OR
o Distance from Point D to Point ___________________
 DEMONSTRATION: A different way of making a wave will be demonstrated. Describe how
this differs from the wave you made in the lab.
_________________________________________________________________________
_________________________________________________________________________
 A longitudinal wave is a wave in which the particles of the medium move
___________________________ to the direction of the wave (energy) motion.
 Anatomy of a Longitudinal Wave

Compressions: The part of the medium where the particles are
____________________ ________________________________.

Rarefactions: The part of the medium where the particles are _______________
_________________________.
 Sound waves are longitudinal waves
 Nice animation: http://www.acs.psu.edu/drussell/demos/waves/wavemotion.html
How fast is that wave going?
 The wavespeed is the ________________________ a wave travels per unit time.

Wavespeed symbol: v

Wavespeed units: meters per second (m/s)
 The frequency is the number of complete _______________ passing a point every second that
passes.

Frequency symbol: f

Frequency units: __________________ (Hz)

The “wavespeed equation” This is how we MEASURE wavespeed.
wavespeed = wavelength* frequency
v = l* f
 The period is the amount of _____________ is takes for one wave to pass.

Period symbol: T

Period units: __________________________

Example: if 3 waves pass by in 6 seconds, the period (time per wave) is 2 seconds

Period is the number of seconds per wave and frequency is the number of waves per
second. Thus, period and frequency are inverses of each other.
Period =
T=

1
f
1
Frequency
1
or f =
T
Example: if the T = 2 seconds, then to find the frequency:
𝟏
𝟏
𝒇
𝟐
𝑻 = = = 𝟎. 𝟓 𝐇𝐳
What affects wavespeed:
 Outside factors that DO affect wavespeed:

A change to the medium changes the speed of the wave

You can change the medium by changing the:
o medium itself (ex: sound traveling in air vs. water)
o tension (ex: changing how “tight” a guitar string is
o density
o elasticity
o temperature etc.
 Factors that DO NOT affect wavespeed:


When listening to a concert:

Do louder sounds reach you before quieter sounds? __________________

Do higher notes reach you faster than lower notes? ________________
These things DO NOT affect wave speed:
o amplitude
o wavelength
o frequency
Demonstrations using the wave demonstrator:
DEMONSTRATION: You will see a wave travel from one medium to another. Record your
observations.
_________________________________________________________________________
__________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
Simple Harmonic Motion: similar to waves

Simple Harmonic Motion: Repetitive back-and-forth movement through a
central, or equilibrium, position in which the maximum displacement on
one side is equal to the maximum displacement on the other.

Examples of Simple Harmonic Motion: pendulum, mass moving up and
down on a spring, child on a swing, etc.
Behaviors of Waves:
(Show with Wave Demonstrator and Refraction Simulation.)
All waves can exhibit the following behaviors:
 Reflection: to bounce off a barrier or interface between 2 mediums.
 Refraction: to bend as the wave passes into a new medium.
 Transmission: to pass through into a new medium.
 Interference: when two or more waves pass through each other, and their
amplitudes add.